基于状态观测器的风电机组单机储能系统虚拟惯量控制

摘要

随着风电在电力系统中的渗透率越来越高,特别是大规模风电场或风电集群集中接入电网,风电出力的波动性对电力系统的调度和频率稳定等诸多方面带来了不可忽视的影响.针对变速恒频风电机组通过变频器并网、机组功率与系统频率完全解耦、不具备惯量响应特性的问题,就风电机组单机储能系统基于扩张状态观测器提出一种利用储能补偿风电机组惯量的控制策略.该控制策略采用扩张状态观测器估计系统频率的变化率,将未知测量噪声和外部扰动作用作为扩张状态进行估计可较好地解决频率变化率测量中的噪声对控制效果干扰的问题.同时还可以通过变参数控制实现风储联合系统虚拟惯量的动态调节.以1.5MW直驱风电机组配备350kW储能为对象的仿真结果表明该策略能够在不影响风电机组最大功率追踪的情况下,有效补偿风电机组虚拟惯量,使风储联合系统输出功率迅速响应系统的频率变化,较比例微分(PD)虚拟惯量控制能更好地抑制电网频率波动,提高风电机组对电网的频率支撑能力.%With the penetration of wind power in grid becoming higher and higher, especially large-scale wind park or wind groups access to transmission grid, the wind power variation has brought a lot of impacts on power scheduling, frequency stability and many other aspects. Since the generator and system frequency are fully decoupled by the full-size converter, the variable speed wind turbines have no inertia contribution to the power grid. Aiming at the problem, an energy storage device control strategy for inertia compensation of wind turbine is presented in this paper, based on the extended state observer (ESO). The ESO is adopted to estimate the differential signal of system frequency, which can estimate the effects of unknown measurement noise and external interference. It can solve the problems that come from interference of frequency change rate measurement. At the same time, the virtual inertia of the wind storage integrated system can be adjusted through variable parameter controls. To verify the control strategy, the simulation was done based on a 1.5MW gearless permanent magnet synchronous generator (PMSG) wind turbine and a 350kW battery storage system. The results showed that the strategy could compensate the virtual inertia of wind turbine without affecting the maximum power point tracking, and the output power of wind-energy storage system can response to the system frequency variation rapidly. Compared with proportional-differential (PD) virtual inertia control, the power grid frequency fluctuation can be better suppressed, and the frequency stability of the power system and the grid-friendship of wind turbine are improved.