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.
[1] 赵畹君. 高压直流输电工程技术[M]. 2版. 北京: 中国电力出版社, 2011. [2] 许汉平, 杨炜晨, 张东寅, 等. 考虑换相失败相互影响的多馈入高压直流系统换相失败判断方法[J]. 电工技术学报, 2020, 35(8): 1776-1786. Xu Hanping, Yang Weichen, Zhang Dongyin, et al.Commutation failure judgment method for multi-infeed HVDC systems considering the interaction of commutation failures[J]. Transactions of China Electrotechnical Society, 2020, 35(8): 1776-1786. [3] 贺永杰, 向往, 周家培, 等. LCC-MMC串联型混合直流输电系统小信号建模[J]. 电工技术学报, 2021, 36(7): 1492-1506. He Yongjie, Xiang Wang, Zhou Jiapei, et al.Small-signal modelling of LCC-MMC series hybrid HVDC transmission system[J]. Transactions of China Electrotechnical Society, 2021, 36(7): 1492-1506. [4] 曾南超. 高压直流输电在我国电网发展中的作用[J]. 高电压技术, 2004, 30(11): 11-12. Zeng Nanchao.Role of HVDC transmission in the power system development in China[J]. High Voltage Engineering, 2004, 30(11): 11-12. [5] 郭春义, 宁琳如, 王虹富, 等. 基于开关函数的LCC-HVDC换流站动态模型及小干扰稳定性[J]. 电网技术, 2017, 41(12): 3862-3868. Guo Chunyi, Ning Linru, Wang Hongfu, et al.Switching-function based dynamic model of LCC-HVDC station and small signal stability analysis[J]. Power System Technology, 2017, 41(12): 3862-3868. [6] Rahimi E, Gole A M, Davies J B, et al.Commutation failure analysis in multi-infeed HVDC systems[J]. IEEE Transactions on Power Delivery, 2011, 26(1): 378-384. [7] Guo Chunyi, Zhao Chengyong, Iravani R, et al.Impact of phase-locked loop on small-signal dynamics of the line commutated converter-based high-voltage direct-current station[J]. IET Generation, Transmission & Distribution, 2017, 11(5): 1311-1318. [8] 郭春义, 蒋雯, 郑安然, 等. 弱交流系统下STATCOM对LCC-HVDC小干扰稳定裕度的影响研究[J]. 中国电机工程学报, 2018, 38(19): 5679-5686, 5925. Guo Chunyi, Jiang Wen, Zheng Anran, et al.Impact of STATCOM on the small-signal stability margin of LCC-HVDC under weak AC grid conditions[J]. Proceedings of the CSEE, 2018, 38(19): 5679-5686, 5925. [9] 王长江, 姜涛, 刘福锁, 等. 基于轨迹灵敏度的暂态过电压两阶段优化控制[J]. 电工技术学报, 2021, 36(9): 1888-1900, 1913. Wang Changjiang, Jiang Tao, Liu Fusuo, et al.Two-stage optimization control of transient overvoltage based on trajectory sensitivity[J]. Transactions of China Electrotechnical Society, 2021, 36(9): 1888-1900, 1913. [10] 高本锋, 王刚, 刘毅, 等. LCC-HVDC送端电网等值方案研究[J]. 电工技术学报, 2021, 36(15): 3250-3263, 3271. Gao Benfeng, Wang Gang, Liu Yi, et al.Study on equivalence method of AC system in sending-end of LCC-HVDC[J]. Transactions of China Electrotechnical Society, 2021, 36(15): 3250-3263, 3271. [11] 杨汾艳, 徐政, 张静. 直流输电比例-积分控制器的参数优化[J]. 电网技术, 2006, 30(11): 15-20. Yang Fenyan, Xu Zheng, Zhang Jing.Study on parameter optimization of HVDC PI controllers[J]. Power System Technology, 2006, 30(11): 15-20. [12] 郭春义, 赵成勇, 李广凯, 等. 基于Simplex算法的VSC-HVDC控制参数优化[J]. 电力自动化设备, 2010, 30(9): 13-17. Guo Chunyi, Zhao Chengyong, Li Guangkai, et al.Control parameter optimization based on Simplex algorithm for VSC-HVDC[J]. Electric Power Automation Equipment, 2010, 30(9): 13-17. [13] 喻锋, 王西田, 杨煜, 等. 一种混合遗传算法在HVDC定电流控制器参数优化中的应用[J]. 电力系统保护与控制, 2014, 42(9): 126-131. Yu Feng, Wang Xitian, Yang Yu, et al.An application of hybrid genetic algorithm in the parameters optimization of HVDC constant current controller[J]. Power System Protection and Control, 2014, 42(9): 126-131. [14] 叶运铭, 汪娟娟, 陈威, 等. 基于小干扰动态模型的LCC-HVDC系统控制器参数优化方法[J]. 南方电网技术, 2021, 15(4): 1-9. Ye Yunming, Wang Juanjuan, Chen Wei, et al.Controller parameters optimization method for LCC-HVDC system based on small-interference dynamic model[J]. Southern Power System Technology, 2021, 15(4): 1-9. [15] 杨佳艺, 赵成勇, 苑宾, 等. 基于粒子群优化算法的VSC-HVDC系统的控制参数优化策略[J]. 电力自动化设备, 2017, 37(12): 178-183. Yang Jiayi, Zhao Chengyong, Yuan Bin, et al.Parameter optimization of VSC-HVDC control system based on particle swarm optimization algorithm[J]. Electric Power Automation Equipment, 2017, 37(12): 178-183. [16] 郑安然, 郭春义, 殷子寒, 等. 提高弱交流系统下混合多端直流输电系统小干扰稳定性的控制参数优化调节方法[J]. 电工技术学报, 2020, 35(6): 1336-1345. Zheng Anran, Guo Chunyi, Yin Zihan, et al.Optimal adjustment method of control parameters for improving small-signal stability of hybrid multi-terminal HVDC system under weak AC condition[J]. Transactions of China Electrotechnical Society, 2020, 35(6): 1336-1345. [17] 刘宛菘, 秦博宇, 张若微, 等. 模块化多电平换流器型多端高压直流输电控制参数优化方法[J]. 电机与控制学报, 2021, 25(2): 10-18, 27. Liu Wansong, Qin Boyu, Zhang Ruowei, et al.Optimal design method of control parameters for MMC-MTDC[J]. Electric Machines and Control, 2021, 25(2): 10-18, 27. [18] 黄伟煌, 李明, 郭铸, 等. 基于小干扰稳定性的多端混合高压直流输电系统控制参数分析与优化方法[J]. 电网技术, 2020, 44(8): 2941-2949. Huang Weihuang, Li Ming, Guo Zhu, et al.Control parameter analysis and optimization method of multi-terminal hybrid HVDC transmission system based on small signal stability[J]. Power System Technology, 2020, 44(8): 2941-2949. [19] 崔鹏, 郭春义, 蒋雯, 等. 基于二次型指标和蒙特卡洛方法的含STATCOM的LCC-HVDC系统的控制参数优化[J]. 中国电机工程学报, 2020, 40(12): 3858-3866. Cui Peng, Guo Chunyi, Jiang Wen, et al.Optimization of control parameters of LCC-HVDC system with STATCOM based on Lyapunov stability and Monte Carlo algorithm[J]. Proceedings of the CSEE, 2020, 40(12): 3858-3866. [20] Guo Chunyi, Cui Peng, Zhao Chengyong.Optimization and configuration of control parameters to enhance small-signal stability of hybrid LCC-MMC HVDC system[J]. Journal of Modern Power Systems and Clean Energy, 2021, 10(1): 213-221. [21] 张嗣瀛, 高立群. 现代控制理论[M]. 2版. 北京: 清华大学出版社, 2017. [22] 贺永杰, 向往, 赵静波, 等. 一种用于LCC-HVDC系统小干扰稳定性分析的改进动态相量模型[J]. 电网技术, 2021, 45(4): 1417-1428. He Yongjie, Xiang Wang, Zhao Jingbo, et al.Modified dynamic phasor model for small-signal stability analysis of LCC-HVDC system[J]. Power System Technology, 2021, 45(4): 1417-1428. [23] 江克证, 朱建行, 胡家兵, 等. 计及开关过程的LCC-HVDC小信号建模及其对电力系统电磁尺度稳定性分析[J]. 清华大学学报(自然科学版), 2021, 61(5): 395-402. Jiang Kezheng, Zhu Jianhang, Hu Jiabing, et al.Small-signal modeling of LCC-HVDC systems with switching for electromagnetic timescale stability analyses of power systems[J]. Journal of Tsinghua University(Science and Technology), 2021, 61(5): 395-402. [24] 崔翔. 无损耗传输线物理模拟的集总电路级联数目确定方法[J]. 中国电机工程学报, 2017, 37(9): 2561-2570. Cui Xiang.Chained number of lumped-circuits for physical analogy of the lossless transmission lines[J]. Proceedings of the CSEE, 2017, 37(9): 2561-2570. [25] 蒋雯. 含STATCOM的LCC-HVDC系统小信号稳定性研究[D]. 北京: 华北电力大学(北京), 2019. [26] 金畅. 蒙特卡洛方法中随机数发生器和随机抽样方法的研究[D]. 大连: 大连理工大学, 2006. [27] 朱陆陆. 蒙特卡洛方法及应用[D]. 武汉: 华中师范大学, 2014. [28] 傅闯, 叶运铭, 汪娟娟, 等. 基于D分割法的LCC-HVDC系统控制器参数整定方法[J/OL]. 电力系统自动化, 1-17[2022-02-26]. http://kns.cnki.net/kcms/detail/32.1180.TP.20220114.1056.002.html. Fu Chuang, Ye Yunming, Wang Juanjuan, et al. D-partition method based controller parameter setting method for LCC-HVDC system[J/OL]. Automation of Electric Power Systems,1-17[2022-02-26].http://kns.cnki.net/kcms/detail/32.1180.TP.20220114.1056.002.html.
2023, Vol. 38 
