光伏并网系统参与电压调节的有功和无功协调控制策略研究

摘要

针对配电网线路阻抗大、分布式光伏并网系统无功调压能力有限,导致光伏电源在有功出力较大时并网点(PCC)电压越上限问题,在深入分析光伏系统PCC电压特性基础上,提出一种光伏逆变器有功和无功协调控制策略.在该控制策略下,光伏系统实时跟踪监测PCC电压变化,PCC电压不越限时,逆变器按最大功率点跟踪(MPPT)输出;PCC电压越上限时,优先利用逆变器剩余容量进行无功调压,若剩余容量不足,调节逆变器有功输出,并动态计算有功、无功最佳输出值,保证将PCC电压调节至满足要求的前提下,实现逆变器有功输出最大化、无功输出最佳化.算例结果验证了控制策略的有效性.%The impedance of the distribution network is large,the reactive power voltage regulation of the distributed PV grid-connected system is weak,so the voltage of point of common coupling exceeds the upper limit when the active power is larger than PV power supply.Based on the analysis of the PCC voltage characteristics of PV system,the active and reactive power coordination control strategy of PV inverter is proposed in this paper.In this control strategy,the voltage of PCC is tracked by PV system in real time.When the voltage of PCC is normal,the inverter will output in the way of maximum power point tracking (MPPT).When the voltage of PCC exceeds the upper limit,the inverter will regulate the voltage by using the remaining capacity preferentially.If the remaining capacity is insufficient,the inverter will adjust active output and dynamically calculate the active and reactive best output values.In this way,the voltage of PCC is adjusted in a appropriate range to achieve the active output maximization and reactive output optimization of inverter.The results of the example verify the effectiveness of the control strategy.