逆变型分布式电源并网运行暂态稳定机理与评估方法

Transient Stability Mechanism and Judgment for Inverter Interfaced Distributed Generators Connected with Public Grids

逆变型分布式电源(IIDG)是可再生能源在配电网中的重要应用方式,其稳定运行依赖于控制策略及其所接入的配电网系统。在配电网发生暂态事件时,IIDG暂态响应复杂,易出现输出功率、功角等波动或振荡。该文以IIDG控制系统及其接入电网的数学模型为基础,分析功角特性曲线,以功角曲线簇提出其暂态稳定性判据。对影响IIDG暂态稳定性的并网参数、额定功率进行系统性分析,比较不同参数对暂态稳定性的影响。通过刻画暂态过程,提出了暂稳迭代判定法,迭代计算暂态事件下IIDG的功角变化并对其暂态稳定性进行判断。在PSCAD/EMTDC中建立仿真算例,验证了IIDG暂态稳定性机理,并通过改变并网的网络参数,证明了暂稳迭代判定法的有效性与准确性。

The inverter interfaced distributed generator(IIDG)connected with the distributed grid is an important application of renewable energy.The stable operation of the IIDG depends on its control system and the connected grid.The transient response of the IIDG is complex,and it is prone to fluctuations or oscillations in output power and power angle when a transient evert occurs.This paper analyzes the controller and the structure of the connected grid to build the active power curves of the IIDG.The transient stability criteria are also proposed by analyzing the active power curve cluster.The influence of the network parameters and nominal power on the transient stability is also analyzed.A transient stability iteration algorithm is proposed by establishing the transient process of the IIDG,which can calculate the power angle variation.Study cases built in PSCAD/EMTDC verify the proposed mechanism,and show that the transient stability iteration algorithm is effective and feasible.