柔性接地系统与配电网的交互影响机理及优化控制方法研究

Zero-sequence voltage is a key coefficient for fault arc-extinguishing, protection and overvoltage in the neutral ineffectively grounded distribution power grid. Distribution network flexible grounding technology can realize grounding fault residual current constraint, three-phase unbalance overvoltage reduction, residual current incremental grounding protection, and ferroresonance overvoltage suppression through controlling the zero-sequence voltage. Based on the proposed flexible grounding concept and the preliminary researched accomplishment, this project focuses on zero-sequence voltage active control theory and method. For one thing, the interaction between the single-phase inverter and the distribution network is to be researched and the zero-sequence active control device topology optimal method is to be proposed. For another, the current control method based on the output voltage and current decoupling is to be researched, which assures the independent control of output current and promoting the overall performance of the control system. The research achievement is anticipated to realize a precise, effective and reliable zero-sequence voltage control system, and enhance the theory of fault suppression and protection in distribution network.

零序电压是决定中性点非有效接地配电网故障消弧、保护和过电压的一个重要参数，配电网柔性接地技术通过有源控制零序电压，灵活控制接地故障残流、降低三相不平衡过电压、有利于实现残流增量接地保护及抑制铁磁谐振过电压，是配电网接地与调谐的一个重要发展方向。项目在课题组提出的配电网柔性接地概念及前期研究的基础上，重点研究基于电力电子系统的零序电压有源控制理论与方法。一方面研究有源逆变回路与配电网的相互作用机理，理论上探讨配电网零序阻抗对注入电流回路效率和谐波的影响，提出配电网零序电压有源控制装置拓扑结构优化方法；另一方面研究基于输出电流与零序电压解耦的柔性接地装置电流控制方法，实现输出电流的独立控制，并提升装置控制系统的整体性能。研究成果有助于实现精确、高效、可靠的配电网零序电压控制系统，促进配电网接地消弧与保护技术的发展。

配电网柔性接地技术通过有源控制零序电压，灵活控制接地故障残流、降低三相不平衡过电压及抑制铁磁谐振过电压，可解决配电网长期存在的单相接地故障消弧和零序过电压抑制难题，本项目分析了柔性接地装置与配电网的交互作用机理，揭示了柔性接地装置对配电网零序电压的控制和作用原理；提出了复杂条件下的配电网单相高阻接地故障相辨识方法，为有源电压消弧方法的实现提供重要依据；提出了柔性接地装置有源电压消弧控制方法，实现了配电网单相接地故障电流的全补偿；提出了配电网线路分布参数不平衡情况下的位移电压补偿电流生成方法和零序过电压抑制控制方法，实现了配电网零序过电压的快速准确抑制；搭建了实验室样机平台，并对原理方法进行了验证。项目研究成果有利于提高配电网供电可靠性，保障供配电设备安全运行。