基于戴维南等效的过电压在线控制方法

Online Prevention and Control of Overvoltage in Photovoltaic Distribution Network

随着分布式光伏在配电网中渗透率不断提高,配电网电压越限问题日益受到关注。针对电网与光伏间的负荷因不协调运作而产生的过电压问题,提出了一种基于戴维南等效的过电压在线预防控制策略。在正常运行条件下,光伏系统按最大功率跟踪输出;当并网点电压高于预设电压值,通过戴维南参数和预设电压值实时预测光伏输出功率上限,根据自适应下垂曲线动态调节使得并网点电压保持在指定的范围内。该方法可避免逆变器频繁启停,使光伏系统在配电网中始终保持在线状态,同时最大限度地提高光伏并网发电量。利用IEEE 34节点系统进行仿真,结果验证了该控制策略的有效性。

With the increasing penetration rate of distributed photovoltaics in the distribution network,the issue of voltage exceeding limits in the distribution network is receiving increasing attention.An online overvoltage prevention and control strategy based on the Thevenin equivalent to address the issue of overvoltage caused by the uncoordinated operation of loads between the power grid and photovoltaic systems is proposed.Under nor-mal operating conditions,the photovoltaic system tracks its output at maximum power.When the voltage at the grid connection point is higher than the preset voltage value,the upper limit of photovoltaic output power is pre-dicted in real-time through the Thevenin parameter and the preset voltage value.The adaptive droop curve is dynamically adjusted to keep the grid connection point voltage within the specified range.This method avoids frequent start-up and shutdown of the inverter,keeps the photovoltaic system always online in the distribution network,and maximizes photovoltaic power generation.The effectiveness of this control strategy is verified through simulation of an IEEE 34-node system.