柔性互联电网短路电流计算等值模型分析

Analysis of equivalent model for short-circuit current calculation of flexible interconnected power grid

在我国“双碳”目标的推动下,电力系统将有可再生分布式能源大量接入及电力电子设备广泛应用。柔性多状态开关功率平滑可调、响应快速,能有效提高分布式能源的消纳能力,增强电网调控灵活性,但也给电网的潮流分析及继电保护带来了新的挑战。针对含柔性多状态开关的配电网短路电流计算问题,首先阐述了柔性多状态开关的基本原理与控制策略;然后通过分析短路期间柔性多状态开关控制环响应时序,建立了柔性多状态开关故障端电压型变流器暂态等值模型与参数计算方法,并基于该模型给出了短路电流工程计算方法;最后基于Matlab搭建了对比仿真模型,验证了等值模型与参数计算方法的有效性,为柔性互联电网的继电保护电流整定提供了一种简便实用的短路电流工程计算方法。

Driven by China’s“dual carbon”goal,the power system will face the situation of massive access of renewable distributed energy and extensive application of power electronic equipment.Flexible multi-state switch can effectively improve the absorption capacity of distributed energy and enhance the flexibility of power grid regulation because of its smooth and adjustable power flow control and fast response,but it also brings new challenges to power flow analysis and relay protection of power grid.In this paper,the short-circuit current calculation of distribution network with flexible multi-state switch is studied.Firstly,the basic principle and control strategy of the flexible multi-state switch are described.Secondly,by analyzing the response time sequence of the flexible multi-state switch control loop during short circuit,the transient equivalent model and parameter calculation method of the voltage source converter at the fault end of the flexible multi-state switch are established,and the short-circuit current engineering calculation method is given based on the model.Finally,a comparative simulation model is built in Matlab to verify the validities of the equivalent model and parameter calculation method,which provides a simple and practical short-circuit current engineering calculation method for relay protection current setting of flexible interconnected power grid.