基于控制网侧电流的光伏并网变流器控制策略

Control Strategy of Grid Current for a Photovoltaic Grid-connected Converter

提出了一种光伏发电并网变流器的控制策略,通过直接控制电网电流为正弦,实现有功功率的功率变换与传输的同时,补偿本地负载谐波电流和无功电流。外环采用直流电压控制,通过最大功率点跟踪算法获得直流电压的控制参考信号,然后利用电压控制器输出与电网电压的基波因子相乘直接获取电流控制参考信号,通过内环电流直接对电网电流进行跟踪控制,从而控制电网电流为不含谐波和无功分量的正弦有功电流。该方法只需要一个电流互感器和两个电压互感器用于检测电网电流、电网电压和直流电压,且无需坐标变换、算法简单、计算延时少。实验结果证明了所提方法的可行性。

A control strategy for photovoltaic grid-connected generation in order to control the grid currents as sinusoidal directly, which not only convert and transfer to the active power effectively, but also compensate harmonic and reactive power.The reference voltage of the direct current is achieved from the maximum power point tracking algorithm.The current loop directly tracking controls the grid current, whose reference signal is obtained from the multiplication of the voltage controller output and the fundamental factor.Therefore, the grid current will become sinusoidal active current without harmonic and reactive power.The detecting method is simple without complicate math transform and only three sensors are necessary for supply current, supply voltage and direct current voltage.The experimental results demonstrate the proposed method is feasible.