电工技术学报  2023, Vol. 38 Issue (7): 1751-1764    DOI: 10.19595/j.cnki.1000-6753.tces.211915
电力系统与综合能源 |
提高LCC-HVDC在弱交流系统下的稳定性和动态性能的控制参数优化方法
郭春义, 吕乃航, 张加卿
新能源电力系统国家重点实验室(华北电力大学) 北京 102206
Optimization of Control Parameters to Enhance Stability and Dynamic Performance of LCC-HVDC under Weak AC Condition
Guo Chunyi, Lü Naihang, Zhang Jiaqing
State Key Laboratory for Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing 102206 China
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摘要 基于电网换相换流器的高压直流(LCC-HVDC)系统在逆变侧连接弱交流系统时可能出现小信号失稳以及动态性能恶化的问题,需要同时关注系统的稳定性和动态性能。而现有的控制参数优化方法所用的目标函数往往仅描述系统的稳定性或动态性能,而不能同时兼顾。针对这一问题,该文提出一种利用能够同时衡量系统稳定性和动态性能的能量衰减指标作为目标函数的LCC-HVDC控制参数优化方法。首先,建立LCC-HVDC系统的小信号模型,通过根轨迹和灵敏度分析辨识影响系统稳定性的关键控制参数;然后,通过能量衰减指标计算适用于不同工况的优化可行域,在可行域内以能量衰减指标为目标函数用蒙特卡洛算法对关键控制参数进行优化;最后,通过不同运行点下的测试,证明经过参数优化的LCC-HVDC在弱交流系统下的稳定性和动态性能有明显提升,优化后的控制参数适用于传输功率不同的工况,证明了优化方法的有效性和适用性。
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关键词 电网换相换流器的高压直流(LCC-HVDC)弱交流系统能量衰减指标控制参数优化    
Abstract:Small signal instability and dynamic performance deterioration may occur when LCC-HVDC system is connected to weak AC system at the inverter side. It is necessary to pay attention to the stability and dynamic performance of the system at the same time. However, the objective function used in the existing optimization methods for control parameters can only describe the stability or dynamic performance of the system.To solve this problem, this paper proposed an LCC-HVDC control parameters optimization method using the energy reduction index which can simultaneously measure the system stability and dynamic performance as the objective function.
Firstly, the small signal model of LCC-HVDC system is established. On this basis, the dominant mode affecting the system stability under the weak AC system conditions is identified by the root locus analysis. Also, the control parameters sensitivity of the dominant mode is calculated, and the key control parameters with higher sensitivity are selected as the optimized parameters.
Then, the energy reduction index ηmin is derived as the objective function of control parameter optimization, whose physical meaning is the minimum reduction rate of system energy in the state space. The larger ηmin is, the better stability and dynamic performance the system has. Therefore, the objective of optimization is to obtain the combination of control parameters in which case ηmin is maximized.
The range of control parameters with a relatively large ηmin value is selected as the optimization feasible region, and the parameters in the feasible region can meet the basic requirements of stability and dynamic performance of the system under different power transmission operating points. Subsequently, the Monte Carlo algorithm is adopted to optimize the key control parameters. The combinations of random numbers are used as the values of the optimized control parameters, and the corresponding energy reduction index values are calculated. New random number combinations are generated continuously until the amount of random number combinations in the feasible region reaches a set value. In this process, the random number combination that maximizes the index in the feasible region is recorded as the final optimized control parameters.
The following conclusions can be drawn from the theoretical analysis and simulation results: (1) The proportional coefficients of the phase locked loop and constant DC current/voltage controllers have relatively great influence on the stability of LCC-HVDC system under the weak AC grid conditions. (2) The optimized control parameters can significantly improve the small-signal stability and dynamic performance of LCC-HVDC system connected to weak AC grid, and the optimization results are suitable for different transmission power conditions. Meanwhile, the commutation failure recovery ability of the system with optimized control parameters is also improved to some extent, thereby verifying the effectiveness of the proposed optimization method.
Key wordsLine commutated converter based high voltage direct current (LCC-HVDC)    weak AC system    energy reduction index    control parameters optimization   
收稿日期: 2021-11-25     
PACS: TM721.1  
通讯作者: 郭春义 男,1984年生,博士,副教授,研究方向为直流输电等。E-mail:chunyiguo@outlook.com   
作者简介: 吕乃航 男,1998年生,硕士研究生,研究方向为直流输电等。E-mail:3319368060@qq.com
引用本文:   
郭春义, 吕乃航, 张加卿. 提高LCC-HVDC在弱交流系统下的稳定性和动态性能的控制参数优化方法[J]. 电工技术学报, 2023, 38(7): 1751-1764. Guo Chunyi, Lü Naihang, Zhang Jiaqing. Optimization of Control Parameters to Enhance Stability and Dynamic Performance of LCC-HVDC under Weak AC Condition. Transactions of China Electrotechnical Society, 2023, 38(7): 1751-1764.
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