基于EWT的分布式光储PCC功率波动自适应平抑方法

Adaptive PCC power fluctuation smoothing method based on EWT for distributed PV-energy storage

分布式光伏在交流侧公共连接点(point of common coupling,PCC)汇流的功率有较大的随机性与波动性,影响电网的稳定运行。为此,提出了基于经验小波变换(empirical wavelet transform,EWT)的分布式光储PCC功率自适应平抑方法。首先,针对混合储能(hybrid energy storage system,HESS)与分布式光伏接入PCC的典型场景,在分析EWT自适应处理波形的特点后,结合功率波动率与储能元件的响应特性,对PCC的光伏原始汇流功率进行EWT分解与优化修正,实现HESS的功率初级分配。之后为避免HESS的荷电状态(state of charge,SOC)频繁越限,提出了一种主动功率补偿的SOC控制策略,通过主动改变储能的参考信号使其SOC在安全范围内工作。结合实际数据的仿真验证表明,该平抑方法能够自适应地实现光伏出力的合理分解与功率分配,在延长储能使用寿命的同时有效满足并网功率波动的要求,为平抑光伏输出功率波动提供了新思路。

The aggregated power of distributed PV at the point of common coupling(PCC)on the AC side has large randomness and volatility,affecting the stable operation of the grid.To help combat this,an adaptive PCC power fluctuation smoothing method based on empirical wavelet transform(EWT)is proposed.First,this paper focuses on a typical scenario of a hybrid energy storage system(HESS)and distributed PV access to the PCC.After analyzing the characteristics of the EWT adaptive processing waveform,and combining with the power fluctuation rate and energy storage element response characteristics,the EWT decomposition and optimal correction of the original PV aggregated power are applied to achieve HESS primary power distribution.Then to avoid the HESS state of charge(SOC)from frequently crossing its limit,an active power compensation control is proposed to make it work within the safe range by actively changing the energy storage reference signal.A simulation example combined with actual data shows that the smoothing method can adaptively realize reasonable decomposition and power distribution of PV output and effectively meet the requirements of grid-connected power fluctuation while extending the service life of energy storage.This provides a new idea for smoothing PV output power fluctuation.