低压系统电压约束下光伏发电准入容量确定的简化解析式研究

Study on Simplified Analytical Formulas for Calculating Permitted Capacity of Photovoltaic Generation in Low-voltage System Under Voltage Constraints

针对配电网中光伏发电接入容量不断增加造成电压越限的潜在问题,研究了一种确定配电网光伏发电准入容量的简化方法。首先,构建了含光伏发电的配电网简化模型,推导了在低压系统电压约束下光伏发电运行于单位功率因数时准入容量确定的解析式;进一步在光伏发电出力过高造成电压越限情况下,给出了确定所需附加无功补偿量的解析式;最后,分析了光伏逆变器无功出力受功率因数限制的特点,提出了一种超前功率因数下光伏发电准入容量确定的简化解析式方法。借助 DIgSILENT 仿真软件,案例分析在一个 IEEE 33 节点系统中展开,通过对比文中方法计算结果与时域仿真结果,二者之间偏差满足实际工程要求,验证了该方法的有效性。此外,还分析了文中方法存在误差的原因。

For the potential problem of out of limit of voltage due to high penetration of photovoltaic (PV) generation in low voltage distribution networks,a simplified analytical approach for calculating the maximum capacity of the PV generation is studied in this paper. It firstly constructs the simplified model of distribution grid containing PV generation,derives the analytical formula for determining the permitted capacity of photovoltaic installations with unit power factor under the voltage constraint of low voltage system,based on the simplified network model. Furthermore,the analytical formula for determining the required additional reactive power compensation is given when the voltage exceeds the limit due to excessive output of photovoltaic generation. Finally,the characteristics of the photovoltaic inverter reactive power output are analyzed,and a simplified technique for determining the permitted capacity of photovoltaic power generation under the leading power factor is proposed.A case analysis is developed in one IEEE 33 node system with the help of DIgSILENT software,The effectiveness of the method is verified by way of comparing the calculation result with the method in the paper and time domain simulation result and the deviation between them complies with actual engineering requirement.Moreover,the reason of the error existed in the paper is also analyzed.