中国电气工程学报（英文）

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1. Review of Inductance Identification Methods Considering Inverter Nonlinearity for PMSM^*

Qiwei Wang, Jiqing Xue, Gaolin Wang, Yihua Hu, Dianguo Xu

中国电气工程学报（英文） 2024, 10 (2): 1-15. DOI: 10.23919/CJEE.2023.000046

摘要（2147）

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Permanent magnet synchronous motors (PMSMs) are widely used in high-power-density and flexible control methods. Generally, the inductance changes significantly in real-time machine operations because of magnetic saturation and coupling effects. Therefore, the identification of inductance is crucial for PMSM control. Existing inductance identification methods are primarily based on the voltage source inverter (VSI), making inverter nonlinearity one of the main error sources in inductance identification. To improve the accuracy of inductance identification, it is necessary to compensate for the inverter nonlinearity effect. In this study, an overview of the PMSM inductance identification and the related inverter nonlinearity self-learning methods are presented.

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2. Overview of Torque Ripple Minimization Methods for Permanent Magnet Synchronous Motors Based on Harmonic Injection^*

Peng Yi, Wenzhi Zheng, Xianglin Li

中国电气工程学报（英文） 2024, 10 (2): 16-29. DOI: 10.23919/CJEE.2023.000045

摘要（635）

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Permanent magnet synchronous motors (PMSMs) are widely used because of their high power/torque density and high efficiency, particularly in applications with strict requirements for arrangement space or weight, such as in the electric vehicle (EV) and aerospace fields. Recently, the PMSM torque ripple problem has received increasing interest because PMSM drive requirements continuously improve. For applications with complex transmission and a wide speed range, torque ripple can easily cause system resonance, which deteriorates the driving performance. The research status and latest progress in the minimization of PMSM torque ripple based on harmonic injection are discussed. First, the causes of PMSM torque ripple are analyzed. Subsequently, the research status of the PMSM analytical model is introduced, and multiple current harmonic control and optimization methods are described in detail. Finally, future development trends in this field are analyzed.

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3. Wavelet Synchro-squeezing Transform and Dynamic Threshold Supported Symmetrical Power Swing Technique for Modern Transmission Network

Monalisa Biswal, Kumar Raja Andanapalli, Papia Ray

中国电气工程学报（英文） 2024, 10 (2): 30-43. DOI: 10.23919/CJEE.2024.000064

摘要（604）

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Distance relays are prone to symmetrical power swing phenomenon. To mitigate this issue, a dynamic threshold-supported algorithm is proposed. A single logic is not supposed to be secure for all cases. Thus, a supervisory algorithm, as proposed in this study, can aid in the improvement of the immunity of the relay during swing cases and be sensitive to symmetrical faults. In the developed stages, a three-phase power signal was used and processed in two different steps: (i) extraction of the effective intrinsic mode function (IMF) selected from the Kurtosis analysis using the wavelet synchro-squeezing transform, and (ii) estimation of the average Euclidean distance index using the absolute values of the decomposed IMF’s. The adaptive threshold facilitated resistance to swing situations. At the onset of a symmetrical fault, the proposed algorithm efficiently discriminated among events using a dynamic threshold. The IEEE 39-bus test system and Indian Eastern Power Grid networks were modelled using PSCAD software, and cases were generated to test the efficacy of the method. The impact of the proposed method on a large-scale wind farm was also evaluated. A comparative analysis with other existing methods revealed the security and dependability of the proposed method.

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4. Research on Distributed Coordination Control Method for Microgrid System Based on Finite-time Event-triggered Consensus Algorithm^*

Lizhen Wu, Heng Yang, Jianping Wei, Wendong Jiang

中国电气工程学报（英文） 2024, 10 (2): 103-115. DOI: 10.23919/CJEE.2024.000053

摘要（395）

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Microgrids are networked control systems with multiple distributed generators (DGs). Microgrids are associated with many problems, such as communication delays, high sampling rates, and frequent controller updates, which make it challenging to realize coordination control among the DGs. Therefore, finite-time consensus algorithms and event-triggered control methods are combined to propose a distributed coordination control method for microgrid systems. The DG in the microgrid system serves as an agent node in the control network, and a distributed secondary controller is designed using finite-time consensus algorithm, such that the frequency and voltage restoration control has a faster convergence time and better anti-interference performance. The event-triggered function was designed based on the state information of the agents. The controller exchanges the state information at the trigger instants. System stability is analyzed using the Lyapunov stability theory, and it is verified that the controller cannot exhibit the Zeno phenomenon in the event-triggered process. A simulation platform was developed in Matlab/Simulink to verify that the proposed control method can effectively reduce the frequency of controller updates during communication delays and the burden on the communication network.

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5. Defect Detection in c-Si Photovoltaic Modules via Transient Thermography and Deconvolution Optimization^*

Zekai Shen, Hanqi Dai, Hongwei Mei, Yanxin Tu, Liming Wang

中国电气工程学报（英文） 2024, 10 (1): 3-11. DOI: 10.23919/CJEE.2023.000043

摘要（313）

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Defects may occur in photovoltaic (PV) modules during production and long-term use, thereby threatening the safe operation of PV power stations. Transient thermography is a promising defect detection technology; however, its detection is limited by transverse thermal diffusion. This phenomenon is particularly noteworthy in the panel glasses of PV modules. A dynamic thermography testing method via transient thermography and Wiener filtering deconvolution optimization is proposed. Based on the time-varying characteristics of the point spread function, the selection rules of the first-order difference image for deconvolution are given. Samples with a broken grid and artificial cracks were tested to validate the performance of the optimization method. Compared with the feature images generated by traditional methods, the proposed method significantly improved the visual quality. Quantitative defect size detection can be realized by combining the deconvolution optimization method with adaptive threshold segmentation. For the same batch of PV products, the detection error could be controlled to within 10%.

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6. Design and Manufacture of Dual-gate DDSCR with High Failure Current and Holding Voltage^*

Xingtao Bao, Yang Wang, Yujie Liu, Xiangliang Jin

中国电气工程学报（英文） 2024, 10 (2): 116-125. DOI: 10.23919/CJEE.2024.000061

摘要（311）

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High-voltage controller area network (CAN) buses have a harsh working environment and require a robust electrostatic discharge (ESD) design window. Thus, ordinary silicon-controlled rectifier (SCR) devices do not satisfy these design requirements. To streamline the design and manufacturing of SCRs, this study proposes a novel dual-gate dual-direction SCR (DG-DDSCR) with a high failure current and holding voltage. First, four polysilicon gates, Gate_A1, Gate_A2, Gate_C1, and Gate_C2, were introduced to the N+ and P+ middle regions of the anode and cathode. When the voltage acts on the anode, the electric field generated by the polysilicon gate strengthens the SCR current path while promoting the release of ESD current in the substrate path. Specifically, the holding voltage of the DG-DDSCR and failure current derived from the test results of a transmission line pulse (TLP) are 29.4 V and 16.7 A, respectively. When the clamping voltage was 40 V, the transient current release of the structure can reach 11.61 A, which met the specifications of the CAN bus ESD window and was suitable for the ESD protection of the target application.

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7. Investigation of Eccentric PM on High-frequency Vibration in FSCW PM Machine Considering Force Modulation Effect^*

Jinghua Ji, Weizhi Jiang, Wenxiang Zhao, Tong Liu

中国电气工程学报（英文） 2024, 10 (2): 59-69. DOI: 10.23919/CJEE.2024.000063

摘要（303）

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This study investigates the negative influence of an eccentric permanent-magnet (PM) design on high-frequency electromagnetic vibration in fractional-slot concentrated-winding (FSCW) PM machines. First, an analytical expression for the sideband current harmonics was derived using the double Fourier series expansion method. Then, the characteristics of the flux-density harmonics are studied from the perspective of the space-time distribution and initial phase relationship. The influence of the eccentric PM design on high-frequency electromagnetic and concentrated forces was studied based on the electromagnetic force modulation effect. Consequently, an eccentric PM design is not conducive to reducing the 2p^th-order high-frequency electromagnetic forces. Finally, two FSCW PM machines with conventional and eccentric PM designs are manufactured and tested to verify the theoretical analysis. The results show that the eccentric PM design worsens high-frequency vibrations.

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8. Accurate 3D Thermal Network Development for Direct-drive Outer-rotor Hybrid-PM Flux-switching Generator

Ali Zarghani, Mohammad Farahzadi, Aghil Ghaheri, Karim Abbaszadeh

中国电气工程学报（英文） 2024, 10 (2): 80-92. DOI: 10.23919/CJEE.2024.000059

摘要（285）

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Heat and thermal problems are major obstacles to achieving high power density in compact permanent magnet (PM) topologies. Consequently, a comprehensive, accurate, and rapid temperature rise estimation method is required for novel electric machines to ensure safe and reliable operations. A unique three-dimensional (3D) lumped parameter thermal network (LPTN) is presented for accurate thermal modeling of a newly developed outer-rotor hybrid-PM flux switching generator (OR-HPMFSG) for direct-drive applications. First, the losses of the OR-HPMFSG are calculated using 3D finite element analysis (FEA). Subsequently, all machine components considering the thermal contact resistance, anisotropic thermal conductivity of materials, and various heat flow paths are comprehensively modeled based on the thermal resistances. In the proposed 3-D LPTN, internal nodes are considered to predict the average temperature as well as the hot spots of all active and passive components. Experimental measurements are performed on a prototype OR-HPMFSG to validate the efficiency of the 3-D LPTN. A comparison of the results at various operating points between the developed 3-D LPTN, experimental test, and FEA indicates that the 3-D LPTN quickly approximates the hotspot and mean temperature of all components under both transient and steady states with high accuracy.

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9. Analytical Solution of a Fractional-slot Double-layer-winding Open-slot Vernier Permanent Magnet Machine with Tooth Tips

Weibing Wang, Ming Cheng

中国电气工程学报（英文） 2024, 10 (2): 44-58. DOI: 10.23919/CJEE.2024.000057

摘要（280）

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An analytical solution (ANA) for a fractional-slot double-layer-winding open-slot vernier permanent magnet (VPM) machine with tooth tips is presented. Magnetic vector potential equations are analytically solved using the technique of variable separation in four subdomains in a two-dimensional polar coordinate system. Based on the solved magnetic vector potential, the flux density distribution, torque, flux linkage, inductance, electromotive force (EMF) and power factor are analytically developed. An 18-slot/32-rotor-pole prototype is analyzed, and the results match well with the finite element analysis (FEA), which validates that the ANA consumes less time than FEA. Therefore, the tooth tips are optimized using the ANA to improve the average torque. Moreover, the ANA can be used to evaluate the demagnetization withstand capabilities of permanent magnets. The material utilization, slot-filling factor, EMF, and torque are compared between the models with three and four subdomains. Finally, an experimental prototype is constructed and tested, and the results validate the ANA.

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10. Ice-covered Environmental Adaptability Assessment for Overhead Contact System in High-speed Railways^*

Huan Zhang, Wenfu Wei, Like Pan, Zefeng Yang, Guizao Huang, Yuxin Liu, Xing Chen, Ziqian Yang, Guangning Wu

中国电气工程学报（英文） 2024, 10 (2): 70-79. DOI: 10.23919/CJEE.2024.000058

摘要（268）

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High-speed trains rely on pantograph-catenary systems (PCSs) to collect electrical energy from power systems. However, the dynamic interaction between the pantograph and the catenary system may become mismatched once ice accumulates on the overhead conductors. More frequent arcing may occur within the PCS during train operation, posing an unpredictable threat to operational safety. Therefore, it is crucial to evaluate the ability of overhead contact system (OCS) to withstand ice-covered variability during line desgin. A new strategy is proposed to evaluate the adaptive performance of an OCS under various icing conditions. First, a dynamic model considering icing conditions is constructed to simulate the interaction within the PCS. Five different OCS structures with various icing thicknesses are studied. The parameters of the contact force within the PCS and proportion of high-possibility arcing moments are obtained. The dependence of the contact force on the icing thickness and pantograph displacement has been illustrated in the form of cloud maps. Finally, the OCS sensitivity coefficient is calculated, and ice-covered environmental adaptability assessments for the five different OCS structures are compared.

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11. A Simple Primary Key Algorithm Based Shade Dispersion Method for Maximizing PV Power Generation under Partial Shading Conditions^*

Prabhakaran Koothu Kesavan, A. Karthikeyan, Manoj Kumar, Sushant Mandal

中国电气工程学报（英文） 2024, 10 (2): 93-102. DOI: 10.23919/CJEE.2024.000067

摘要（251）

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The output power generation of a photovoltaic (PV) array reduces under partial shading, resulting in multiple local maxima in the PV characteristics and inaccurate tracking of the global maximum power point (GMPP). Various interconnection schemes are available to reduce power losses under partial shading. In this study, a primary key algorithm is proposed for distributing shading across an array. This method is suitable for any n×n PV array configuration and involves fewer calculations and variables, leading to reduced computational complexity. The power generations of a 9×9 PV array under four different shading conditions were compared with the configurations of: total cross-tied (TCT) and Su Du Ku, physical relocation and fixed column position of modules with fixed electrical connection (PRFCPM-FEC), and magic square (MS) and improved-odd-even-prime (IOEP). The advantage of the proposed method is that once the primary key elements are obtained, the remaining array elements are numbered in a simpler manner. The results obtained using the proposed arrangement show that the power is enhanced with reference to the TCT and is comparable to the Su Do Ku, PRFCPM-FEC, MS, and IOEP reconfigurations.

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12. Advanced Electrical Motors and Control Strategies for High-quality Servo Systems - A Comprehensive Review^*

Ming Cheng, Jiawei Zhou, Wei Qian, Bo Wang, Chenchen Zhao, Peng Han

中国电气工程学报（英文） 2024, 10 (1): 63-85. DOI: 10.23919/CJEE.2023.000048

摘要（247）

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Recent technological advancements have propelled remarkable progress in servo systems, resulting in their extensive utilization across various high-end applications. A comprehensive review of high-quality servo system technologies, focusing specifically on electrical motor topologies and control strategies is presented. In terms of motor topology, this study outlines the mainstream servo motors used across different periods, as well as the latest theories and technologies surrounding contemporary servo motors. In terms of control strategies, two well-established approaches are presented: field-oriented control and direct torque control. Additionally, it discusses advanced control strategies employed in servo systems, such as model predictive control (MPC) and fault tolerance control, among others.

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13. Editorial for the Special Issue on Emerging Technology and Advanced Application of Nondestructive Detection for Power Equipment

中国电气工程学报（英文） 2024, 10 (1): 1-2. DOI: 10.23919/CJEE.2024.000055

摘要（240）

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The rapid development of clean and renewable energy technologies represented by wind and solar energy, as well as the continuous growth of load demand, have put forward higher requirements for the safe operation of the power equipment. The performance of power equipment based on traditional dielectric materials is often limited by various defects generated during molding, transportation, assembly, and operation, which cannot meet the reliability requirements of power systems in the new situation. Nondestructive detection is an essential technical method in industrial development, which can detect and evaluate the defect and damage status of in-service equipment, key components, and materials without damaging the object.

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14. Experimental Study on the Effect of State of Charge on Failure Propagation Characteristics within Battery Modules^*

Kuijie Li, Yalun Li, Xinyu Rui, Yuancheng Cao, Liyun Fan, Xuning Feng

中国电气工程学报（英文） 2023, 9 (3): 3-14. DOI: 10.23919/CJEE.2023.000007

摘要（237）

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To investigate the effect of different states of charge (SOC) on the thermal runaway (TR) propagation behaviors within lithium-ion-batteries based energy storage modules, an experimental setup was developed to conduct failure propagation tests on battery modules at an SOC of 97%, 85%, and 50%. The result indicates that an increase in the SOC of batteries can decrease the TR trigger temperature, making batteries trigger TR earlier and reducing the average failure propagation time between two adjacent cells. In addition, the failure propagation tests reveal that at higher SOCs, the TR reaction becomes more violent, the maximal reaction temperature is also much higher, and the damage to the battery module is severe. Compared to the battery module with 97% SOC, the TR trigger time of the battery module with 50% SOC was postponed by approximately 57.8%. Meanwhile, the average failure propagation time got prolonged by approximately 36.0%. Thus, this study can provide references for the thermal safety design of energy-storage battery modules.

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15. A Review of Variable-inductor-based Power Converters for Eco-friendly Applications: Fundamentals, Configurations, and Applications^*

Zijie He, Guidong Zhang, Zexiang Chen, Samson S. Yu

中国电气工程学报（英文） 2023, 9 (3): 50-71. DOI: 10.23919/CJEE.2023.000030

摘要（222）

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Modern eco-friendly industries such as renewable energy systems, electric vehicles (EVs), and light-emitting diodes (LEDs) have led to technological advancements in power electronics. Switching-based power converters have limited working ranges and can cause significant harmonics and oscillations in the output voltage and current. Introducing variable inductors can help solve this problem by changing the inductance without resorting to extreme switch duty cycles. Despite their advantages, there is still a lack of comprehensive reviews of variable inductor applications in power converter design. A thorough and in-depth review of variable inductance control in power conversion is presented, including its significance, working principle, core structure, modeling method, and typical applications. Traditionally, an inductor works in its linear magnetic region; its inductance in a power converter is considered constant, and the converter operates under fixed working conditions. However, a broad range of working conditions is required for power converters in practical applications. This is typically realized by changing the duty cycles of the switches. The working principle of variable inductance is reviewed, and the application of variable inductance control in power converters is presented, which will further help power electronics researchers and engineers design flexible and resilient power converters.

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16. Li-ion Battery Failure Warning Methods for Energy-storage Systems

Peihao Wu, Nawei Lyu, Yuhang Song, Xin Jiang, Yang Jin

中国电气工程学报（英文） 2024, 10 (1): 86-100. DOI: 10.23919/CJEE.2023.000037

摘要（218）

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Energy-storage technologies based on lithium-ion batteries are advancing rapidly. However, the occurrence of thermal runaway in batteries under extreme operating conditions poses serious safety concerns and potentially leads to severe accidents. To address the detection and early warning of battery thermal runaway faults, this study conducted a comprehensive review of recent advances in lithium battery fault monitoring and early warning in energy-storage systems from various physical perspectives. The focus was electrical, thermal, acoustic, and mechanical aspects, which provide effective insights for energy-storage system safety enhancement.

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17. Simulation of Ultrasonic Propagation in Transformers within Thermal Fields and Intelligent Methodology for Hot-spot Temperature Recognition^*

Dongxin He, Dechao Yang, Xinhua Guo, Jiefeng Liu, Haoxin Guo, Qingquan Li, Gilbert Teyssedre

中国电气工程学报（英文） 2024, 10 (1): 35-47. DOI: 10.23919/CJEE.2024.000052

摘要（206）

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Hot-spot temperature of transformer windings is a crucial indicator of internal defects. However, current methods for measuring the hot-spot temperature of transformers do not apply to those already in operation and suffer from data lag. This study introduces a novel inversion method that combines ultrasonic sensing technology, multiphysics simulation, and the K-nearest neighbors algorithm. Leveraging the penetrative ability and temperature sensitivity of ultrasonic sensing, a detailed physical field simulation model was established. This study extensively investigates the characteristics of ultrasonic wave signals inside transformers. The investigation includes different temperature fields, ranging from 40 ℃ to 110 ℃ at 10 ℃ intervals, and various ultrasonic wave emitter conditions. By extracting the key features of the acoustic signals, such as the peak time, propagation time, and peak amplitude, an accurate inversion of the winding hot-spot temperature is successfully achieved. The results demonstrate that this method achieves a high accuracy rate (98.57%) in inverting the internal winding hot-spot temperatures of transformers, offering an efficient and reliable new approach for measuring winding hot-spot temperatures.

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18. Aging Mechanism and Life Estimation of Photovoltaic Inverter DC-link Capacitors in Alternating Humid and Thermal Environment^*

Quanyi Gao, Shuaibing Li, Yi Cui, Yongqiang Kang, Haiying Dong

中国电气工程学报（英文） 2024, 10 (1): 48-62. DOI: 10.23919/CJEE.2024.000054

摘要（204）

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DC-link capacitors play a vital role in managing ripple voltage and current in converters and various devices. This study focuses on exploring the aging characteristics of DC-link capacitors in alternating humid and thermal environments aligned with the operational conditions in photovoltaic and wind power applications. Adhering to relevant power equipment standards, we designed a 24-h alternating humid and thermal aging environment tailored to the requirements of DC-link capacitors. An aging test platform is established, and 20 widely used metallized polypropylene film capacitors are selected for evaluation. Parameters such as the capacitance, equivalent series resistance (ESR), and phase angle are assessed during aging, as well as the onset time and extent of aging at various intervals. This study focuses on the aging mechanisms, analyzing electrode corrosion, the self-healing process, and dielectric aging. Fitting the aging characteristics enabled us to calculate the lifespan of the capacitor and predict it under different degrees of capacitance decay. The results show that under alternating humid and thermal conditions, capacitance attenuation and ESR increase exhibit exponential nonlinearity, influenced by factors such as the oxidation and self-healing of capacitive metal electrodes, dielectric main-chain fracture, and crystal transformation. This study underscores the pivotal role of encapsulation in determining the aging decay time.

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19. Value Evaluation Method for Pumped Storage in the New Power System^*

Yumin Peng, Ying Yang, Man Chen, Xuelin Wang, Yijun Xiong, Mu Wang, Yikai Li, Bushi Zhao

中国电气工程学报（英文） 2023, 9 (3): 26-38. DOI: 10.23919/CJEE.2023.000029

摘要（202）

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When integrating the generation of large-scale renewable energy, such as wind and solar energy, the supply and demand sides of the new power system will exhibit high uncertainty. Pumped storage power stations can improve flexible resource supply regulation in the power system, which is the key support and important guarantee for building low-carbon, safe, and efficient new power systems. Limited by the current operation mode and electricity price mechanism, the pumped storage power station cost cannot be effectively recovered, and the value cannot be reasonably compensated, resulting in difficult return on investment, single investment subjects, and notable industry development difficulties. According to the operational requirements of the new power system, combined with the various functions of pumped storage power stations, the value of pumped storage power stations in the new power system was analyzed. Based on the equivalent value substitution principle and system operation simulation, a pumped storage value evaluation method for the new power system was proposed. The new power system operation was simulated considering the dispatching model of wind and photovoltaic power abandonment penalties. Under the same dispatching objectives, the output of various power sources and power generation operating costs with and without pumped storage power stations in the system were compared. From economic, safety, social, and environmental benefit perspectives, a quantitative model of the pumped storage power station value was established, covering seven dimensions: asset investment savings, power generation operating cost reduction, flexible adjustment capability improvement, system resilience enhancement, power outage loss reduction, renewable energy consumption, and emission reduction promotion. Based on the new power system operation and planning data for southern China, the value of typical pumped storage power stations was analyzed, and the results showed that with new power system’s construction and development, the value of pumped storage power stations is increasing, and the value structure is closely related to power grid characteristics. This value evaluation method could provide references for pumped storage investment decisions, subsidy policies, and price mechanisms to fully utilize the role of pumped storage power stations and promote high-quality development of new power systems.

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20. Erosion Characteristics of Oil-immersed On-load Tap Changer Contacts Under Varying Contact Speeds and Pressures

Zongying Li, Shuaibing Li, Yongqiang Kang, Zheng Li, Hongwei Li

中国电气工程学报（英文） 2024, 10 (1): 21-34. DOI: 10.23919/CJEE.2023.000044

摘要（201）

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With the growing demand for precise voltage adjustment and reactive regulation, the frequent operation of on-load tap changers (OLTCs) in oil-immersed systems has led to increased erosion of switch contacts by arcs during the switching process. This erosion causes significant wear on the contacts, thereby reducing their lifespan. Therefore, the present study aims to investigate the behavior and mechanism of arc erosion on contact surfaces in oil-immersed OLTCs. To achieve this, a self-designed friction and wear test device for OLTC contacts was utilized to conduct experiments at various sliding speeds and contact pressures. Additionally, finite element analysis was employed to validate the experimental results regarding the influence of sliding speed on arc energy. The surface morphology of the contacts was observed using an optical microscope. The findings revealed that as the sliding speed increased, the arc energy, arc initiation rate, and contact resistance initially exhibited an upward trend, then decreased, and eventually increased again. The minimum values were observed at a sliding speed of 90 mm/s. Moreover, the arc energy, arc initiation rate, and contact resistance decreased gradually as the contact pressure increased. After reaching a contact pressure of 1.5 N, the variation in the arc energy stabilized. At lower contact pressures, arc erosion dominated the wear on the contact surface. However, at higher contact pressures, the wear transitioned from predominantly arc erosion to a combination of mechanical wear and arc erosion. In summary, experimental and analytical investigations provided insights into the effects of sliding speed and contact pressure on the behavior of arc erosion, contact resistance, and surface damage of OLTC contacts in oil-immersed systems.

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21. Resilience-oriented Valuation for Energy Storage Amidst Extreme Events^*

Youzhen Wu, Jianxiao Wang, Yiyang Song, Yunyun Xie

中国电气工程学报（英文） 2023, 9 (3): 15-25. DOI: 10.23919/CJEE.2023.000031

摘要（194）

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In power grids, the frequency is increasing of extreme accidents which have a low probability but high risk such as natural disasters and deliberate attacks. This has sparked discussions on the resilience of power grids. Energy-storage systems (ESSs) are critical for enhancing the resilience of power grids. ESSs, with their mechanism of flexible charging and discharging, adjust energy usage as needed during disasters, thereby mitigating the impact on the grid and enhancing security and resilience. This, in turn, ensures the power system’s stable operation. Currently, there is limited systematic research quantifying the economic value of energy storage in resilience scenarios. Therefore, a model and methodology were proposed to quantify the value of energy storage systems for enhancing grid resilience during extreme events. A two-stage stochastic optimization mathematical model was developed. The first stage involves pre-deployment based on day-ahead expectations, and the second stage involves simulating potential failure scenarios through real-time scheduling. Considering the temporal dimension, the energy storage systems with flexible regulation capabilities was used as emergency power sources to reduce occurrences of load-shedding. Here, a novel index was proposed that quantifies the resilience value of energy storage as the economic value of energy storage per unit of capacity, as reflected in the emergency dispatch model. This index helps determine the balance between the energy storage investment cost and resilience value. Finally, an IEEE-30 node transmission system was used to verify the feasibility and effectiveness of the proposed method. The findings revealed a significant improvement in the resilience value, with a 23.49% increase observed when energy storage systems were implemented compared to the scenario without energy storage systems. The optimal capacity configurations for the flywheel, lithium-ion batteries, and pumped hydro storage were 10 MW, 11 MW, and 12 MW, respectively, highlight their potential to maximize value in experimental system.

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22. Filtered High Gain Observer for an Electric Vehicle’s Electro-hydraulic Brake: Design and Optimization Using Multivariable Newton-based Extremum Seeking

Jamal El-bakkouri, Hamid Ouadi, Fouad Giri, Mohamed Khafallah

中国电气工程学报（英文） 2023, 9 (4): 73-87. DOI: 10.23919/CJEE.2023.000039

摘要（189）

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Designing high-gain observers (HGOs) for the state estimation of an electric vehicle’s electrohydraulic brake (EHB) system is challenging. This type of observer is applicable to model nonlinearities and constant feature gains. However, they are very sensitive to measurement noise, which is unavoidable in EHB. The first novelty of this study is that it compensates for the measurement noise using a filtered high-gain observer (FHGO) to ensure EHB state estimation. The proposed FHGO provides an estimate of the master cylinder pressure, motor current, and rotor speed from measurements of the rotor position. The second novelty is the design of an extremum-seeking (ES) optimization loop to adjust the FHGO gains online. The performance of the developed FHGO with ES-based online gain optimization was highlighted in the presence of model uncertainties and output measurement noise using a Matlab/Simulink simulation. The superiority of the FHGO (even with a fixed gain) over a standard high gain observer (SHGO) was also demonstrated.

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23. Modified Sliding Mode Observer-based Direct Torque Control of Six-phase Asymmetric Induction Motor Drive

Krunal Shah, Abid Mansuri, Rakesh Maurya

中国电气工程学报（英文） 2023, 9 (3): 111-123. DOI: 10.23919/CJEE.2023.000026

摘要（187）

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In this study, a six-phase induction asymmetric induction motor (SPAIM) was examined, whose performance surpasses that of its three-phase counterpart, with regard to the torque density, torque pulsation, fault tolerance, power rating per inverter lag, and noise characteristics. Speed-encoder-less direct torque control (DTC) for SPAIM with virtual voltage vectors (VVVs) and a modified sliding mode observer (MSMO) are described. The SPAIM model was developed using a stationary α-β frame for DTC. The conventional DTC of the SPAIM drive is a simple extension of DTC for a 3-Φ motor drive that yields higher distortion in the stator currents. To mitigate the large amount of distortion in the stator current, VVVs were used to significantly reduce the harmonic content in the stator currents. Furthermore, to overcome the large amount of chattering observed in the case of a traditional sliding mode observer, particularly under low-speed operation, the MSMO was employed to reduce chattering even under low-speed operation. The performance of the proposed observer was verified under all the operating conditions suitable for the propulsion mode of an electric vehicle using Matlab/Simulink, and the results were experimentally validated.

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24. Editorial for the Special Issue on Emerging Technology and Advanced Application of Energy Storage in Low-carbon Power Systems

中国电气工程学报（英文） 2023, 9 (3): 1-2. DOI: 10.23919/CJEE.2023.000035

摘要（181）

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25. A Multi-scale Smart Fault Diagnosis Model Based on Waveform Length and Autoregressive Analysis for PV System Maintenance Strategies^*

Siti Nor Azlina M. Ghazali, Muhamad Zahim Sujod, Mohd Shawal Jadin

中国电气工程学报（英文） 2023, 9 (3): 99-110. DOI: 10.23919/CJEE.2023.000023

摘要（180）

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Nonlinear photovoltaic (PV) output is greatly affected by the nonuniform distribution of daily irradiance, preventing conventional protection devices from reliably detecting faults. Smart fault diagnosis and good maintenance systems are essential for optimizing the overall productivity of a PV system and improving its life cycle. Hence, a multiscale smart fault diagnosis model for improved PV system maintenance strategies is proposed. This study focuses on diagnosing permanent faults (open-circuit faults, ground faults, and line-line faults) and temporary faults (partial shading) in PV arrays, using the random forest algorithm to conduct time-series analysis of waveform length and autoregression (RF-WLAR) as the main features, with 10-fold cross-validation using Matlab/Simulink. The actual irradiance data at 5.86 °N and 102.03 °E were used as inputs to produce simulated data that closely matched the on-site PV output data. Fault data from the maintenance database of a 2 MW PV power plant in Pasir Mas Kelantan, Malaysia, were used for field testing to verify the developed model. The RF-WLAR model achieved an average fault-type classification accuracy of 98 %, with 100% accuracy in classifying partial shading and line-line faults.

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26. Characterization of Electrical Tree Degradation of Epoxy Resin under Thermal and Temperature Stresses by Photoelastic Effect^*

Hein Htet Aung, Yuhuai Wang, Jin Li, Ying Zhang, Tatsuo Takada

中国电气工程学报（英文） 2024, 10 (1): 12-20. DOI: 10.23919/CJEE.2023.000047

摘要（162）

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Epoxy resin is widely used in the support, insulation, and packaging components of electrical equipment owing to their excellent insulation, thermal, and mechanical properties. However, epoxy-resin insulation often suffers from thermal and mechanical stresses under extreme environmental conditions and a compact design, which can induce electrical tree degradation and insulation failure in electrical equipment. In this study, the photoelastic method is employed to investigate the thermal-mechanical coupling stress dependence of the electrical treeing behavior of epoxy resin. Typical electrical tree growth morphology and stress distribution were observed using the photoelastic method. The correlation between the tree length and overall accumulated damage with an increase in mechanical stress is determined. The results show that compressive stress retards the growth of electrical trees along the electric field, while tensile stress has accelerating effects. This proves that the presence of thermal stress can induce more severe accumulated damage.

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27. Quantitative Comparison of Modular Linear Permanent Magnet Vernier Machines with and without Partitioned Primary^*

Yunpeng Xu, Jinghua Ji, Zhijian Ling, Chen Wang, Wenxiang Zhao

中国电气工程学报（英文） 2023, 9 (3): 72-83. DOI: 10.23919/CJEE.2023.000024

摘要（152）

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A comparison of two modular linear permanent-magnet vernier (LPMV) machines is presented. A modular LPMV machine with a partitioned primary, which can significantly improve the modulation effect, is proposed. Benefitting from the partition design, the space conflict between the permanent magnet (PM) and the armature magnetic field is relieved. First, the topologies of modular LPMV machines with and without a partitioned primary are presented. Then, the effect of the partitioned primary on the modular LPMV machine is analyzed using flux modulation theory. Moreover, analytical expressions for the trapezoidal permeance are derived. In addition, the harmonic components, back electromotive forces, and thrust forces of the machines with and without the partitioned primary are comparatively analyzed. The results reveal that the thrust force density of the LPMV machine with a partitioned primary is increased by 32.3%. Finally, experiments are performed on a prototype machine for validation.

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28. Current Loop Disturbance Suppression for Dual Three Phase Permanent Magnet Synchronous Generators Based on Modified Linear Active Disturbance Rejection Control^*

Dezhi Xu, Hu Yao, Yang He, Wenxiang Zhao

中国电气工程学报（英文） 2024, 10 (1): 101-113. DOI: 10.23919/CJEE.2023.000018

摘要（151）

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A modified four-dimensional linear active disturbance rejection control (LADRC) strategy is proposed for a dual three-phase permanent magnet synchronous generator (DTP-PMSG) system to reduce cross-coupling between the d and q axis currents in the d-q subspace and harmonic currents in the x-y subspace. In the d-q subspace, the proposed strategy uses a model-based LADRC to enhance the decoupling effect between the d and q axes and the disturbance rejection ability against parameter variation. In the x-y subspace, the 5th and 7th harmonic current suppression abilities are improved by using quasi-resonant units parallel to the extended state observer of the traditional LADRC. The proposed modified LADRC strategy improved both the steady-state performance and dynamic response of the DTP-PMSG system. The experimental results demonstrate that the proposed strategy is both feasible and effective.

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29. Inherently Sinusoidal Single-phase Voltage Source Inverter Based on Modified Cuk Cell^*

Misbahul Munir, Wisyahyadi, Arwindra Rizqiawan, Jihad Furqani

中国电气工程学报（英文） 2024, 10 (1): 114-123. DOI: 10.23919/CJEE.2024.000051

摘要（147）

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Renewable energy has become important for electricity generation because of the high air pollution associated with conventional fossil-based energy systems. Conventional fossil-based power plants are gradually transitioning by incorporating renewable energy sources, such as photovoltaic (PV) cells. In a PV system, an inverter converts DC power from solar panels to AC power required to serve common electrical loads. A conventional H-bridge inverter topology has several disadvantages, such as the voltage being not sinusoidal, switching the DC voltage and high common-mode voltage. The common-mode voltage can cause a large leaked capacitive current, which can result in undesirable operation in solar power applications. A common solution to this problem is the addition of a large filter to the input or output of an inverter. An inherent sinusoidal voltage source inverter based on a modified Cuk converter as its basic cell, which simultaneously generates a sinusoidal output voltage and a lower common-mode voltage, is proposed. The proposed topology does not require additional input or output filters. Analytical expressions are derived to confirm the operation of the proposed topology. Simulation results confirm the mathematical analysis. A laboratory-scale experiment is performed to verify the proposed inverter.

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30. Fast Solution Method for the Large-scale Unit Commitment Problem with Long-term Storage^*

Bo Li, Chunjie Qin, Ruotao Yu, Wei Dai, Mengjun Shen, Ziming Ma, Jianxiao Wang

中国电气工程学报（英文） 2023, 9 (3): 39-49. DOI: 10.23919/CJEE.2023.000033

摘要（146）

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Long-term storage (LTS) can provide various services to address seasonal fluctuations in variable renewable energy by reducing energy curtailment. However, long-term unit commitment (UC) with LTS involves mixed-integer programming with large-scale coupling constraints between consecutive intervals (state-of-charge (SOC) constraint of LTS, ramping rate, and minimum up/down time constraints of thermal units), resulting in a significant computational burden. Herein, an iterative-based fast solution method is proposed to solve the long-term UC with LTS. First, the UC with coupling constraints is split into several sub problems that can be solved in parallel. Second, the solutions of the sub problems are adjusted to obtain a feasible solution that satisfies the coupling constraints. Third, a decoupling method for long-term time-series coupling constraints is proposed to determine the global optimization of the SOC of the LTS. The price-arbitrage model of the LTS determines the SOC boundary of the LTS for each sub problem. Finally, the sub problem with the SOC boundary of the LTS is iteratively solved independently. The proposed method was verified using a modified IEEE 24-bus system. The results showed that the computation time of the unit combination problem can be reduced by 97.8%, with a relative error of 3.62%.

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31. FEA-based Geometrical Modification of Switched Reluctance Motor for Radial Force Reduction

Rani S, Jayapragash R

中国电气工程学报（英文） 2024, 10 (1): 124-135. DOI: 10.23919/CJEE.2024.000049

摘要（131）

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Switched reluctance motors (SRMs) are becoming increasingly popular in the automotive sector owing to their robust design. Moreover, SRMs are preferred particularly for EV applications owing to their fault tolerance, magnet-free structure, and high power/torque density. The main concerns of SRM compared to other machines include torque ripple and vibration. The primary cause of vibration is the radial force created by the SRM. A geometry-based modification of the SRM to reduce the radial force without significantly changing the average torque produced is proposed. The primary goal is to design a 4-phase, 8/6 SRM with a lower radial force. Two possible geometrical alterations are proposed: one with square windows and the other with circular holes on the rotor core. The windows are sized and positioned to avoid flux saturation. General criteria are developed for the optimal window size and placement. Finite element analysis (FEA) modelling of the SRM is used to validate its performance. The FEA results are compared with the performance parameters obtained using the analytical method. Utilizes the multiphysics design tool ANSYS to obtain the natural frequencies and associated deformations through modal analysis. Compared to the conventional geometry, the radial force is significantly reduced by providing windows.

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32. TSKARNA-norm Adaption Based NLMS with Optimized Fractional Order PID Controller Gains for Voltage Power Quality

Prashant Kumar, Sabha Raj Arya, Khyati D. Mistry

中国电气工程学报（英文） 2023, 9 (3): 84-98. DOI: 10.23919/CJEE.2023.000025

摘要（129）

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The operation of a dynamic voltage restorer (DVR) is studied using a three-phase voltage source converter (VSC)-based topology to alleviate voltage anomalies from a polluted supply voltage. The control algorithm used included two components. The first is an adaptive Takagi-Sugeno-Kang (TSK)-based adaptive reweighted L₁norm adaption-based normalized least mean square (TSK-ARNA-NLMS) unit, which is proposed for the extraction of fundamental active and reactive components from the non-ideal supply and is further employed to generate the load reference voltage and switching pulse for the VSC. The step size was evaluated using the proposed TSK-ARNA-NLMS controller, and the TSK unit was optimized by integration with the marine predator algorithm (MPA) for a faster convergence rate. The second, a fractional-order PID controller (FOPID), was employed for AC- and DC-link voltage regulation and was approximated using the Oustaloup technique. The FOPID (PI^γD^µ) provides more freedom for tuning the settling time, rise time, and overshoot. The FOPID coefficients (K_i, K_d, K_p, γ, and µ) were optimized by employing an advanced ant lion optimization (ALO) meta-heuristics technique to minimize the performance index, namely, the integral time absolute error (ITAE) and assess the accuracy of controllers. The DVR performance was validated under dynamic- and steady-state conditions.

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