Evaluation of reactive power control concepts for PV inverters in low-voltage grids

The proportion of renewable energies in power generation has increased significantly in recent years according to the political aims. In low-voltage grids, these are mostly distributed intermittent generation systems such as photovoltaic systems that are connected through inverters to the grid. Thus, the distribution networks have to meet hitherto unfamiliar technical challenges. A temporary reversal of the power flow can cause overvoltage problems. Traditional voltage regulation strategies cannot solve this problem. Consequently, regenerative sources need to be turned off temporarily or on the long term the grid infrastructure has to be extended by the network operator. Therefore, the distributed generation has to take part in the voltage regulation. With the help of reactive power, which is generated by the solar inverters, power capability and voltage quality of the networks can be increased. Thus, grid extension can be delayed or even avoided in many times. This paper presents a new approach to the evaluation of reactive power control strategies. Different reactive power control concepts are simulated and evaluated concerning their efficiency, effectiveness and stability.