基于光伏并网逆变器功率调整的本地电压选择性控制策略

Local Voltage Selective Control Strategy Based on Power Regulation of Photo-voltaic Grid-connected Inverter

针对分布式光伏电源大量接入配电网的趋势,分析了光伏电源对配电网电压分布的影响及并网点电压对逆变器输出功率的灵敏度,针对架空线路配电网提出了一种利用光伏逆变器剩余容量的本地电压选择性控制策略。并网点电压正常时,光伏逆变器运行于单位功率因数下MPPT模式;并网点电压越上限时,过电压调节器工作于无功优先方式,光伏逆变器首先输出抑制过电压所需的感性无功功率,然后根据逆变器剩余容量的限制输出尽可能多的有功功率;并网点电压越下限时,低电压调节器工作于有功优先方式,光伏逆变器首先输出MPPT下的有功功率,然后根据低电压改善的需要和逆变器剩余容量的限制输出相应的容性无功功率。仿真和实验结果表明,这种本地电压控制策略在保障电网电压合格的前提下可以充分利用光伏能量。

As the trend thata large number of access of distributed PV power into distribution grid, the influence of PV power on the voltage distribution of distribution grid and the sensitivity of inverter output power to voltage of grid-connected point is analyzed. A kind of selective control strategy of local voltage by the use of theresidual capacity of the PV inverter is proposed for the overhead line distribution grid. In case of normal voltage at the grid - connected point, the PV inverter operates at MPPT mode under unit power factor. When the voltage of the grid -connected point is above the upper limit, the overvoltage regulator operates at active power mode in priority mode.The PV inverter outputs the inductive reactive power needed for suppressing the overvoltage, then outputs as much as possible active power in accordance with the remaining capacity of the inverter. When the voltage of networking is lower than the lower limit,the low voltage regulator operates at active mode in priority. The PV inverter outputs active power of MPPT mode at first, then outputs corresponding capacitive reactive power in accordance with the need of low voltage improvement and the limit of the remaining capacity of the inverter. It is shown by the simulation and experimental result that this kind of local voltage control strategy can fully use PV energy under premises of assuring qualified grid voltage.