不平衡电网下虚拟同步机的多模式协调策略  

Multi-Mode Coordination Control of Virtual Synchronous Generator under Unbalanced Power Grid

作　　者：潘子迅 杨晓峰[1] 赵锐 崔晨阳 闫涛 Pan Zixun;Yang Xiaofeng;Zhao Rui;Cui Chenyang;Yan Tao(School of Electrical Engineering Beijing Jiaotong University,Beijing 100044 China;State Key Laboratory of Operation and Control of Renewable Energy&Storage Systems China Electric Power Research Institute,Beijing 100192 China)

机构地区：[1]北京交通大学电气工程学院,北京100044 [2]新能源与储能运行控制国家重点实验室(中国电力科学研究院有限公司),北京100192

出　　处：《电工技术学报》2023年第16期4274-4285,共12页Transactions of China Electrotechnical Society

基　　金：新能源与储能运行控制国家重点实验室(中国电力科学研究院有限公司)开放基金资助项目(DGB51202101307)。

摘　　要：新能源并网换流器采用虚拟同步机(VSG)控制有利于提升电网惯量和阻尼水平,但在电网电压不平衡时存在输出电流畸变和瞬时功率脉动的问题。为灵活调控不平衡电网下VSG输出电流质量与功率纹波,该文提出一种VSG多模式协调策略。首先,研究不平衡电网下的VSG瞬时功率脉动抑制机理,在功率恒定模式分析并网电流谐波特征的基础上,利用VSG虚拟功率计算电流参考指令并引入协调系数对其修正;其次,在多谐振电流内环控制下实现VSG电流平衡-功率恒定多模式协调,并研究协调系数影响及其取值区间选取方法;最后,通过仿真与实验结果验证了该文理论分析与所提控制策略的有效性。Virtual synchronous generator control has been widely studied in renewable energy generation to provide equivalent inertia support for the power grid.However,current distortion and power oscillation occur severely when the grid voltage becomes unbalanced,significantly aggravating the power supply quality of renewable energy generation.The existing methods generally take the fundamental-frequency negative-sequence component as the VSG control object to solve the above issues.It is obvious that positive-negative sequence separation increases the calculation burden,and active and reactive power oscillations cannot be suppressed simultaneously.In addition,the mutual influence between optimization targets is rarely considered,so the realization of one optimization target may lead to the deterioration of the others.Therefore,this paper proposes a multi-mode coordination control of VSG and quantitatively analyzes the restrictive relation of VSG current distortion and power fluctuation under an unbalanced power grid.This paper first analyzes the VSG power oscillation mechanism under an unbalanced power grid and then further studies the harmonic components of VSG grid-connected current in constant-power mode.The results indicate that VSG grid-connected current contains low-order odd harmonic components,and the proportion determines double-line frequency active and reactive power oscillation.On this basis,the initial current reference is obtained from VSG virtual power calculation to maintain the operating characteristics of the synchronous machine.Then a multi-resonance current inner loop controls the fundamental frequency current and the harmonic components.It should be noted that the coordination coefficient is introduced to modify the current reference of the harmonic controller,thereby realizing the VSG multi-mode coordination control.Finally,the influence of the coordination coefficient on VSG current quality and power ripple is quantified,and the calculation method of selection range is given.In order to validate th

关 键 词：虚拟同步机 不平衡电网 电流质量 功率纹波 协调控制 

分 类 号：TM46[电气工程—电器]