| 引用本文: | 黄涛,王胜利,谢华,赵青春,顾乔根,徐晓春,戴光武.光伏逆变器短路电流3次谐波及其对保护的影响分析[J].电力自动化设备,2020,40(5): |
| HUANG Tao,WANG Shengli,XIE Hua,ZHAO Qingchun,GU Qiaogen,XU Xiaochun,DAI Guangwu.Analysis of third harmonic current of photovoltaic inverter and its influence on protection[J].Electric Power Automation Equipment,2020,40(5): |
|
| 摘要: |
| 系统发生不对称故障时，短路电流、电压中出现负序分量，导致光伏逆变器直流母线电压中产生二倍频振荡，该振荡分量经过控制回路流通后将在光伏逆变器输出短路电流中生成3次谐波。推导了逆变器输出短路电流3次谐波的解析表达式，计及光伏逆变器的限幅控制特性、负序控制策略、低电压穿越策略，研究了3次谐波的变化特性，然后分析了3次谐波对变压器差动保护电流互感器饱和判据的影响，指出某些工况下光伏逆变器输出短路电流中的3次谐波含量较大，可能造成变压器差动保护误闭锁，导致变压器区内故障无法切除，并提出了相应的应对策略。大量的仿真试验结果验证了理论分析的正确性。 |
| 关键词: 光伏逆变器 3次谐波 限幅特性 负序控制 电流互感器饱和 继电保护 变压器差动保护 |
| DOI：10.16081/j.epae.202004025 |
| 分类号:TM77;TM464 |
| 基金项目: |
|
| Analysis of third harmonic current of photovoltaic inverter and its influence on protection |
|
HUANG Tao1, WANG Shengli2,3, XIE Hua1, ZHAO Qingchun1, GU Qiaogen1, XU Xiaochun1, DAI Guangwu1
|
|
1.Nanjing NR Electric Co.,Ltd.,Nanjing 211102, China;2.School of Electrical and Electronic Engineering, North China Electric Power University, Beijing 102206, China;3.State Grid Xinjiang Electric Power Co.,Ltd.,Urumchi 830002, China
|
| Abstract: |
| When asymmetric fault occurs in the system, negative-sequence components appear in the short circuit current and voltage, which results in 100 Hz oscillation in the DC bus voltage of photovoltaic inverter. A third harmonic component will be generated in the short circuit current of photovoltaic inverter when this 100 Hz component circulating through the control loop. The analytical expression of third harmonic current of photovoltaic inverter is deduced. The characteristics of third harmonic are analyzed considering the influence of current-limited feature of controller, negative-sequence control strategy and low voltage ride through strategy. Then the influence of third harmonic current on transformer differential protection configured with current transformer saturation criterion is studied. It is pointed that the transformer differential protection may be blocked during internal fault of transformer due to the high third harmonic component in short circuit current, and the corresponding countermeasures are proposed to deal with this problem. A large number of simulative results verify the correctness of the theoretical analysis. |
| Key words: photovoltaic inverter third harmonic current-limited characteristic negative-sequence control current transformer saturation relay protection transformer differential protection |
