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。
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 indexηmin 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 largerηmin 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 caseηmin is maximized.The range of control parameters with a relatively largeηmin 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
作者
郭春义
吕乃航
张加卿
Guo Chunyi;LüNaihang;Zhang Jiaqing(State Key Laboratory for Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University,Beijing 102206 China)
出处
《电工技术学报》
EI
CSCD
北大核心
2023年第7期1751-1764,1779,共15页
Transactions of China Electrotechnical Society
