Parameter configuration method for heterogeneous parallel inverter systems based on admittance passivity
DOI：10.19783/j.cnki.pspc.260032
Key Words:paralleled inverters  heterogeneous inverters  weak grid  passivity  admittance synthesis rule
Author NameAffiliation
SUN Cheng 1. School of Automation and Electronic Information, Xiangtan University, Xiangtan 411105, China
2. State Grid Changji Power Supply Company, Changji 831199, China
3. State Key Laboratory of High-efficiency and High-quality Conversion for Electric Power (Hunan University), Changsha 410082, China
4. NR Electric Co., Ltd., Nanjing 211102, China
5. State Grid Turpan Power Supply Company, Turpan 838000, China
6. State Grid Xinjiang Electric Power Co., Ltd., Urumqi 830018, China 
LUO Wenhua 1. School of Automation and Electronic Information, Xiangtan University, Xiangtan 411105, China
2. State Grid Changji Power Supply Company, Changji 831199, China
3. State Key Laboratory of High-efficiency and High-quality Conversion for Electric Power (Hunan University), Changsha 410082, China
4. NR Electric Co., Ltd., Nanjing 211102, China
5. State Grid Turpan Power Supply Company, Turpan 838000, China
6. State Grid Xinjiang Electric Power Co., Ltd., Urumqi 830018, China 
CHEN Zhiyong 1. School of Automation and Electronic Information, Xiangtan University, Xiangtan 411105, China
2. State Grid Changji Power Supply Company, Changji 831199, China
3. State Key Laboratory of High-efficiency and High-quality Conversion for Electric Power (Hunan University), Changsha 410082, China
4. NR Electric Co., Ltd., Nanjing 211102, China
5. State Grid Turpan Power Supply Company, Turpan 838000, China
6. State Grid Xinjiang Electric Power Co., Ltd., Urumqi 830018, China 
LIU Zijun 1. School of Automation and Electronic Information, Xiangtan University, Xiangtan 411105, China
2. State Grid Changji Power Supply Company, Changji 831199, China
3. State Key Laboratory of High-efficiency and High-quality Conversion for Electric Power (Hunan University), Changsha 410082, China
4. NR Electric Co., Ltd., Nanjing 211102, China
5. State Grid Turpan Power Supply Company, Turpan 838000, China
6. State Grid Xinjiang Electric Power Co., Ltd., Urumqi 830018, China 
HU Renxiang 1. School of Automation and Electronic Information, Xiangtan University, Xiangtan 411105, China
2. State Grid Changji Power Supply Company, Changji 831199, China
3. State Key Laboratory of High-efficiency and High-quality Conversion for Electric Power (Hunan University), Changsha 410082, China
4. NR Electric Co., Ltd., Nanjing 211102, China
5. State Grid Turpan Power Supply Company, Turpan 838000, China
6. State Grid Xinjiang Electric Power Co., Ltd., Urumqi 830018, China 
CHANG Xiqiang 1. School of Automation and Electronic Information, Xiangtan University, Xiangtan 411105, China
2. State Grid Changji Power Supply Company, Changji 831199, China
3. State Key Laboratory of High-efficiency and High-quality Conversion for Electric Power (Hunan University), Changsha 410082, China
4. NR Electric Co., Ltd., Nanjing 211102, China
5. State Grid Turpan Power Supply Company, Turpan 838000, China
6. State Grid Xinjiang Electric Power Co., Ltd., Urumqi 830018, China 
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Abstract:In paralleled inverter systems, the non-passive region where the synthesized admittance exceeds the ±90° passivity boundary is one of the key causes of instability in grid-connected operation under weak grid conditions. To address this issue, a heterogeneous inverter parameter configuration method based on admittance optimization is proposed. By appropriately configuring the sampling frequency and LCL filter parameters of newly added inverters, the non-passive regions of the synthesized admittance can be eliminated, thereby enhancing the passivity-based stability of the system without modifying the control structure and parameters of existing inverters. First, based on the Norton equivalent model of parallel inverter systems, stability criteria for the grid-connected current and the coupling current between inverters are established. The grid-connected phase margin and coupling phase margin are defined to reveal the relationship between the violation of the ±90° passivity boundary of synthesized admittance and harmonic resonances among multiple inverters. Then, by combining the resonant and anti-resonant characteristics of the LCL filter with the admittance synthesis rule, coordinated design guidelines for the sampling frequency and filter parameters of heterogeneous inverters are derived. A feasible sampling frequency range for newly added inverters is obtained to ensure that the synthesized admittance satisfies passivity requirements over the entire frequency range. Finally, the effectiveness of the proposed method is verified on an experimental platform consisting of two three-phase grid-connected inverters, each rated at 13.2 kW.
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