Research On Distributed Photovoltaic System’s Influence To Steady-state Operation Of Distribution Network

Distributed photovoltaic (PV) generations have characteristics of small capacity, distributed access points, unstable output, independent control systems from each other, etc. Meanwhile, the distribution network to which PV generations access has a lower voltage class and a smaller capacity, which causes a series problems of distrusted network’s operation. First of all, PV generations’ output is random, which leads to a voltage pulsation, sometimes even excessing voltage limits. Secondly, distributed PV generations have features of randomness and intermittence, and in result distribution network’s control is more difficult. Therefore, if distributed PV generations need to replace traditional power, the problems should be handled to ensure safety and reliability of power supply.This paper analyzed distributed PV system’s influence to steady-state operation of distribution network in theory. The more capacity of PV generations were accessed to distribution network, the higher range of voltage would be. Then, a model of distributed PV system was established in DIgSILENT/PowerFactory. A detailed analysis of distributed PV system’s grid-connection mode and extent of application was launched, according to development of load and distributed PV system in Wuxi. A typical 10kV model of Wuxi medium voltage distribution network was established based on DIgSILENT/PowerFactory. Different PV system models varied due to different access points, access capacities and running modes of PV system in distribution network. Through simulation and calculation, distributed PV system’s influence to distribution network was researched, especially influence of counter power flow in a small load mode. This also gave a solid support to analyses in theory. The research provided a large amount of data after distributed PV system was accessed to distribution network to dispatch and control department. Problems of voltage and power flow pulsations were solved and the ability of distribution network to accept more distributed PV system was enhanced. Above all, a quiker development and larger application of distributed PV system was in sight.