HUANG Xianbin1, LIN Da1, WANG Hui\|fang1, LU Ning2

(1. College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China;

2. Zhejiang Electric Power Corporation Maintenance Branch,Zhejiang University, Hangzhou 310027,China;)

 

 

Abstract: Aiming at solving voltage ride through problem of photovoltaic system, ensuring grid\|connected operation within a certain time as well as providing reactive current, the control strategy of the inverter for Grid Connected Photovoltaic System was studied. Considering the limitation for electric current of inverter, a low voltage ride\|through strategy injected with reactive current in accordance with voltage dropping condition was put forward. On condition of slight voltage sag, this strategy maintains the output of photovoltaic active power to supply reactive power as much as possible. On condition of severe voltage sag, the output was completely reactive power instead of active power. If the power grid was in asymmetrical faults, negative sequence control was adopted to eliminate the fluctuation of active power so as to deduce the setting value of maximum reactive power. It was verified that the controlling strategy was rational and effective by PSACD. The results indicate that this controlling strategy can fully utilize photovoltaic inverter to ensure the output of active power and to provide reactive power support in certain cases, which can help the restoration of voltage in power network.

Key words: low voltage ride through; photovoltaic; reactive current; asymmetric fault