弱受端场景下角型链式STATCOM接入HVDC系统的阻抗建模及稳定性分析  

Impedance Modeling and Stability Analysis for HVDC System With Delta-connected Cascaded STATCOM in Weak Receiving Grid Scenario

作　　者：刘一锋 周小平[1] 洪乐荣 夏海涛 尹寒航 朱仁龙 邓凌峰 陈斌超 LIU Yifeng;ZHOU Xiaoping;HONG Lerong;XIA Haitao;YIN Hanhang;ZHU Renlong;DENG Lingfeng;CHEN Binchao(National Electric Power Conversion and Control Engineering Technology Research Center(Hunan University),Changsha 410082,Hunan Province,China)

机构地区：[1]国家电能变换与控制工程技术研究中心(湖南大学),湖南省长沙市410082

出　　处：《电网技术》2023年第3期1269-1279,共11页Power System Technology

基　　金：国家自然科学基金项目(51907058);湖南省自然科学基金项目(2020JJ5081);长沙市科技计划项目经费(kq2107005)。

摘　　要：为抑制电网换相换流器型高压直流输电(line-commutated converter based high-voltage direct-current,LCC-HVDC)换相失败的发生,静止同步补偿器(static synchronous compensator,STATCOM)在受端系统得到应用。然而随着LCC-HVDC系统的发展及新型电力系统的构建,受端电网呈现弱电网的特征。在弱电网条件下,LCC-HVDC系统、STATCOM与弱受端电网交互作用容易引发谐波振荡。该文采用阻抗分析法分析了含角型链式STATCOM的LCC-HVDC系统与受端电网的交互稳定性问题。首先提出一种改进的LCC交流电流和直流电压计算方式,以避免LCC复杂的换相开关函数的线性化。然后基于谐波状态空间(harmonic state space,HSS)理论,分别推导了LCC-HVDC系统以及角型链式STATCOM的多输入多输出(multi-input multi-output,MIMO)阻抗模型。此外,为了便于阻抗测量和稳定性分析,将MIMO阻抗模型等效转化为单输入单输出(single-input single-output,SISO)阻抗模型,并分析了角型链式STATCOM未接入和接入LCC-HVDC系统下的阻抗特性,揭示了含角型链式STATCOM的LCC-HVDC系统在弱受端电网下振荡的机理。分析表明:LCC-HVDC系统单独运行时受端系统容易在中低频段出现正序谐波振荡,而角型链式STATCOM接入后受端系统容易在中低频段内出现负序谐波振荡。最后,通过仿真验证了分析的正确性。To suppress the commutation failures of the line-commutated converter based high-voltage direct-current(LCC-HVDC) system, the static synchronous compensators(STATCOM) are used in the receiving system. However, with the development of LCC-HVDC system and the construction of new power system, the receiving grid is weakened. Under the weak grid, the interaction between the LCC-HVDC system, the STATCOM and the weak grid may cause oscillations. This paper adopts the impedance method to analyze the interaction stability between the LCC-HVDC system with the delta-connected cascaded STATCOM and the receiving grid. Firstly, an improved calculation for DC voltage and AC current of the LCC is proposed to avoid the linearization of the commutating switching function. Then, based on the harmonic state space(HSS) theory, the multi-input multi-output(MIMO) impedance models of the LCC-HVDC system and the delta-connected cascaded STATCOM are derived. Besides, to facilitate the measurement and stability analysis, their MIMO models are converted to a single-input single-output(SISO) model. Based on the SISO model, the impedance characteristics of the LCC-HVDC system with and without the delta-connected STATCOM are analyzed, which reveals the oscillation mechanism of the LCC-HVDC system with the STATCOM in a weak grid. The analysis shows that: when the LCC-HVDC system operates individually, the receiving system is prone to the positive-sequence harmonic oscillation in the middle-and low-frequency band;while after the delta-connected STATCOM is connected, the receiving system is prone to the negative-sequence harmonic oscillation in this band. Finally, the simulation is performed to validate the analysis.

关 键 词：电网换相换流器型高压直流输电 角型链式静止同步补偿器 谐波状态空间建模 阻抗模型 稳定性分析 

分 类 号：TM721[电气工程—电力系统及自动化]