跟网型并网变换器的稳定域重塑控制策略研究综述

Control Strategy to Reshape the Stable Region for Grid-following Converter:An Overview

大力发展可再生能源是完成能源清洁化转型和实现“双碳”目标的重要途经。在此时代背景下,电力系统结构形态将发生根本性转变,从以同步机电源为主导的传统电力系统发展为由风、光新能源作为主体的新型电力系统。电力电子变换器作为新能源并网发电的接口,具有高度的灵活性与可控性,如何设计控制策略以保证并网变换器的稳定运行是电网高比例可再生能源发展进程中最受关注的重要问题之一。针对复杂电网工况下基于锁相环同步跟网型并网变换器的致稳控制方法,形成了一系列相关研究成果。在具体并网场景下,通过建立合适的跟网型并网变换器的数学模型,并结合与模型适配的稳定性分析方法明晰并网系统失稳机理,进而设计控制策略以改善并网系统稳定性,提升跟网型并网变换器对具体场景的适应性,即经改进控制策略重塑了跟网型并网变换器的稳定运行域。本文依据所采用的跟网型并网变换器模型及稳定性分析方法,将从小扰动意义下的稳定域重塑控制和暂态场景下的稳定域重塑控制两个方面,梳理与归纳迄今的工作进展,并在此基础上探讨保障高比例可再生能源电力系统安全可靠运行仍需研究的技术问题。

Developing renewable energy is an important way to implement the green-oriented transition of energy and achieve the goals of carbon peaking and carbon neutrality.Under such circumstance,the power system configuration will undergo a fundamental transformation,from the traditional power system dominated by synchronous generators to a new one that is dominated by wind and solar sources.As the interface between the power grid and the renewable energy,power electronic converters have high flexibility and controllability.Designing control strategies to ensure the stable operation of grid-connected converters is one of the most important issues in the development of a power system with high penetration of renewable energy.For the grid-following converter(GFC),which synchronizes with the grid via the phase-locked loop,many control strategies have been proposed for ensuring its stable operation under complex grid conditions.For a specific scenario,a mathematical model of the GFC is established.By combining suitable stability analysis methods,the instability mechanism of GFC can be clarified.Then,the stable region of the GFC can be reshaped by improved control strategies.According to the models used in the stability analysis,the proposed strategies can be divided into two categories.One is to reshape the stable region of the GFC in the sense of small-signal disturbance,the other is for reshaping the stable region under transient scenarios.An overview works is presented.Moreover,to facilitate the development of the power system with high penetration of renewable energy,some future investigations towards the stable control of GFCs are discussed.