优化风电惯性响应的变比例系数调速策略

Speed Regulation Strategy Based on Variable Proportion Coefficient for Optimizing Inertial Response of Wind Generator

风电机组的友好型惯性响应对提高高比例风电并网系统的调频特性具有重要意义。该文首先分析最大功率点跟踪（maximum power point tracking,MPPT）运行风电机组利用转速调节实现转动惯量响应的可行性,提出利用变比例系数调节转速指令值的控制方案。其次针对风电机组在惯性支撑过程中对系统调频产生的不利影响,从优化惯性响应特性出发,提出风电机组基于两阶段切换的变比例系数调速策略。在此基础上,基于虚拟惯性时间常数推导惯性响应阶段的变比例系数调整策略,同时为快速恢复风电机组在惯性支撑后的MPPT运行、避免切换对系统调频的二次扰动,采用模糊控制设计该阶段变比例系数的调整策略。最后利用风电并网系统的负荷扰动仿真,论证所研究两阶段变比例系数调速策略提高系统频率响应特性的有效性,仿真结果表明该策略具有充分利用同步发电机调频能力快速恢复风电机组MPPT运行方式的特点。

The friendly inertia support of wind generator is important for improving the frequency dynamic performance of power system connected with high proportion wind power. In this paper, the feasibility for wind generator operating in maximum power point tracking （MPPT） mode to implement rotational inertia response by regulating rotating speed was studied, the control scheme using variable proportion coefficient to regulate the reference value of rotating speed was presented as well. In order to optimize the response characteristics of inertial, the two-stage switching based speed regulation strategy with variable proportion coefficient was proposed to reduce the adverse impact on the system fi-equency regulation brought by wind generator during the process of inertia support. At the same time, the virtual inertia time constant was used to design the variable proportion coefficient for inertial response stage. To quickly recover the wind generator MPPT operation after inertial support and avoid taking the secondary disturbance to system frequency at the switching moment, the control strategy of variable proportion coefficient used for rotating speed regulation in the stage for restoring MPPT operation was studied based on fuzzy control. Finally, the validity of the proposed two-stage speed control strategy was verified by the simulation of load frequency disturbance in the power system integrated with wind power. The simulation results also show that the speed control strategy has the advantage of making full use of the frequency regulation ability of synchronous generator to quickly restore the MPPT operation of wind generator.