基于光伏逆变器无功调节的低压配电网多模式电压控制

Multi-mode Voltage Control in Low Distribution Networks Based on Reactive Power Regulation of Photovoltaic Inverters

针对大规模户用光伏接入引起的低压配电网电压越限问题,以逆变器无功控制为手段,提出了一种多模式逆变器控制策略,以提高低压配电网对光伏的消纳能力。基于电压灵敏度理论,定义了虚拟注入有功功率的概念,实现了节点有功和无功功率之间的折算。根据节点虚拟注入功率将光伏发电的并网分为过电压抑制、欠电压抑制以及网损和功率因数的优化三种模式。当网络出现过电压(欠电压)运行风险时,以风险的抑制为目标调节逆变器无功功率;当网络运行无风险时,则以网损和功率因数的优化作为逆变器的无功调节依据。此外,为了实现就地的协调控制,结合全网电压灵敏度矩阵建立了不同节点光伏逆变器控制参数的优化模型,实现网络无通信条件下的协调电压控制。仿真结果表明,所提的多模式电压控制方法可以有效地抑制网络电压越限,同时使网络损耗和功率因数也得到优化。

In order to mitigate the voltage violation problems in low-voltage distribution network with large penetration of photovoltaic, a multi-mode control strategy of photovoltaic inverter is developed to optimize reactive power of photovoltaic inverter, based on which more photovoltaic generation can be accommodated. Node virtual injection of active power （NVIP） is defined through the voltage sensitivity theory, while the conversion between active and reactive power can be realized by means of voltage regulation. The operation modes of photovoltaics are divided into three kinds according to the NVIP, including overvoltage suppression, undervoltage suppression, power loss and power factor optimization. If the NVIP causes the network overvoltage （undervoltage） operational risk, risk suppression will be taken as the target to regulate the inverter reactive power; whereas, the optimization of power loss and power factor will be taken as the target. Meanwhile, in order to realize on the-spot coordinated control, coordinated control parameters are obtained from the optimization model through voltage sensitivity matrix. The efficiency and flexibility of the proposed method are verified by the low-voltage distribution network with high density residential photovoltaics, the network power loss and power factor are also optimized.