分布式光伏接入对配网系统的暂态特性影响研究

Impact of Distributed Photovoltaic Access on the Transient Characteristics of Distribution Network Systems

随着大量分布式光伏接入配电网,电力系统负荷侧的动态特性产生显著变化,尤其是配电网发生故障时,光伏的有功和无功响应对配网产生较大影响,因此,需要对分布式光伏接入对配网系统的暂态特性进行建模分析。基于光伏并网系统传统结构及控制方式,提出分别适用于低电压和高电压故障下,有功与无功解耦的逆变器保护控制策略,并对模型的高低电压穿越能力进行仿真,并基于逆变器实际电压穿越检测报告进行检验,验证了该光伏并网系统模型具备规定的故障穿越能力。由北京地区某光伏电站实际配网结构、设备参数和光伏控制参数,将传统综合负荷与光伏并网模型并联,建立考虑分布式光伏接入的配电网电磁暂态模型,并等值至110 kV侧,仿真分析了辐照度变化时光伏出力和系统潮流,同时,在配网侧发生三相电压跌落和升高故障条件下,对光伏动态响应和配网各母线潮流进行分析,结果显示,建立的模型能够有效反映动静负荷及光伏系统在稳定运行和高低电压故障条件下对配电网的影响,光伏在进行高低穿控制后能够对电网无功进行有效调节,同时在容量范围内提供有功功率。

With a large number of distributed photovoltaic(PV) access to the distribution network,the dynamic characteristics of the load side of the power system produce significant changes,especially when the distribution network faults occur,the active and reactive responses of the PV have a great impact on the distribution network.Therefore,it is necessary to model and analyze the transient characteristics of distributed photovoltaics integration on the distribution network system.Based on the traditional structure and control mode of PV grid-connected system,an inverter protection control strategy with active and reactive power decoupling is proposed for low-voltage and high-voltage faults,respectively,and the high-and low-voltage ride-through capability of the model is simulated,which verifies that the model of PV grid-connected system has the specified fault ride-through capability.By the actual distribution network structure,equipment parameters and PV control parameters of a PV power plant in Beijing,the traditional integrated load and PV grid-connected model are connected in parallel to establish an electromagnetic transient model of distribution network considering distributed PV access,and equated to the 110 kV side,and the irradiance changes in the photovoltaic output and system currents are simulated and analyzed;at the same time,in the case of a three-phase voltage drop and elevation fault condition on the distribution network side,the PV dynamic response and the At the same time,under the conditions of three-phase voltage dips and rising faults on the distribution network side,the dynamic response of PV and the currents of each bus of the distribution network are analyzed,and the results show that the established model can effectively reflect the dynamic and static loads and the impact of PV system on the distribution network in the conditions of stable operation and high-low voltage faults.