VRB储能系统对风电场LVRT特性影响分析

为满足电网规定的并网风电场必须具有低电压穿越能力（LVRT）要求,提出一种在风电场并网点加入直接功率控制的钒液流电池（VRB）储能系统的拓扑结构来提高风电场LVRT.根据目前风电机组发展趋势风电场采用基于全功率双脉宽调制AC/DC/AC控制策略的逆变器的永磁直驱风电机组（PMSG）,VRB储能系统逆变器采用DC/AC双向功率流动的控制策略.所提出的控制策略通过协调控制风电机组机侧整流器、网侧逆变器和VRB变换器,实现平抑风电场出力和电压跌落时PCC点电压稳定控制及向电网提供一定的无功补偿.仿真结果表明,风速波动和系统电压跌落时,提出的方案可以有效平抑风电场出力波动,提高风电场LVRT能力,减小对系统安全稳定运行的负面影响.

Influences of a VRB Energy Storage System on LVRT Characteristics of a Wind Farm

In order to satisfy the stipulated requirements of power grid that integrated wind farm must have low voltage ride through （LVRT） capacity,a new topological structure,in which the VRB is joined at the wind farm integration point for improving the wind farm＇s LVRT ability is proposed based on the direct power control strategy of the vanadium redox battery （VRB）energy storage system.According to the trend of wind turbine development,the wind farm uses the direct driven permanent magnet synchronous generator （PMSG） with the inverter that is based on the AC/DC/AC control strategy of full power double pulse width modulation.The inverter of VRB energy storage system adopts the DC/AC bidirectional power flow control strategy.The proposed control strategy coordinates the control of the rectifier on wind turbine machine side,the inverter on the grid side and the VRB converter to stabilize the wind farm output and control the PCC voltage stability during voltage drops,and to provide some reactive power compensation.The simulation results show that the proposed scheme can effectively stabilize fluctuations in wind farm output,improve the LVRT capacity of the wind farm,and reduces the negative impact of fluctuation and voltage drops on the system safe and stable operation.