计及锁相环和电流内环暂态过程的逆变型电源故障电流解析方法

Fault Current Analysis Method of Inverter-interfaced Renewable Energy Sources With PLL and Current Inner Loop Transient Processes

为应对新型电力系统中高比例新能源接入对保护原理的挑战,亟需对新能源故障特性进行分析。新能源常以逆变型电源的形式并入电网,而锁相环(phase-locked loop,PLL)作为逆变型电源并网的关键控制环节,其暂态过程直接影响逆变型电源故障特性。该文提出一种计及锁相环和电流内环暂态过程的逆变型电源故障电流解析方法,从锁相环对Park变换的影响入手,明确锁相环对逆变型电源故障电流的影响路径,同时简化锁相环对电流内环暂态过程的影响,通过理论推导得到与锁相环和电流内环参数相关的故障电流解析式,定量分析了故障电流的影响因素,根据电流内环和锁相环暂态特性将故障电流划分了3个阶段并明确各阶段过渡时间,并与仿真波形进行对比验证了有效性。

To cope with the challenge of the high proportion of renewable energy access to protection principles in the new power system,it is urgently required to analyze the fault characteristics of renewable energy.Most renewable energy is connected to the grid as an inverter-interfaced renewable energy source(IIRES),and the phase-locked loop(PLL)serves as a key control loop for IIRES.The transient process of PLL directly affects the fault characteristics of IIRES.This paper proposes a fault current analysis method for IIRES that considers the transient process of both PLL and the inner current loop.Starting from the influence of PLL on Park transform,this paper clarifies the impact of PLL on fault current and simplifies the impact of PLL on the transient process of the inner current loop.The fault current analysis formula related to PLL and inner current loop parameters is theoretically derived to analyze the influencing factors of fault current quantitatively.The fault current is divided into three stages based on the transient characteristics of the inner current loop and PLL,and the duration in each stage is clarified.The effectiveness of the proposed method is validated by comparing it with the simulation waveform.