配电网故障下构网变流器功率解耦与限流两阶段协同控制策略

A Two-Stage Coordinated Control Strategy for Power Decoupling and Fault Current Limiting of Grid-Forming Converters Under Distribution Network Fault Conditions

中文关键词:配电网  构网控制  故障限流  功率耦合  协同控制

keywords:distribution network  grid-forming control  fault current limiting  power coupling  coordinated control

中文摘要:虚拟阻抗控制作为有效的限流策略，通过改变线路的等效阻抗进行故障电流抑制。但现有基于虚拟阻抗控制的限流策略并未充分考虑配电网场景下的功率解耦需求，为此提出分阶段虚拟阻抗控制策略。在稳态及故障电流低于阈值时，投入虚拟负电阻控制，实现功率解耦的同时不抑制故障电流的特性。当故障电流高于阈值时，投入虚拟阻抗控制，实现故障电流的有效抑制。仿真结果表明，所提方法能够保证构网换流器在稳态和故障时一直维持功率解耦能力，保障配电网的电能质量与可靠运行。

Abstract:Virtual impedance control serves as an effective fault current limiting strategy，which suppresses fault currents by changing the equivalent impedance of transmission lines. However，existing current limiting strategies based on virtual impedance control fail to fully consider the power decoupling requirements in distribution network scenarios，for which a phased virtual impedance control strategy is proposed in this paper. When the system is in a steady state and the fault current is below the threshold，virtual negative resistance control is activated to achieve power decoupling without suppressing the fault current. Once the fault current exceeds the threshold，virtual impedance control is activated to achieve effective suppression of the fault current. The results show that the proposed method can ensure that grid-forming converters maintain their power decoupling capability at all times during both steady and fault conditions，thus guaranteeing the power quality and reliable operation of distribution networks.