Research on Capacity Planning of Renewable Energy Grid Integration Based on Effective Short Circuit Ratio

Abstract

In most of the regions of China where large-scale renewable energy is connected to the grid, most of the grid structures are weak, and even local power grids have low voltage levels, weak grid structures, and long-distance small-capacity power transmission. Large-scale renewable energy integration will make the power grid face severe challenges such as capacity planning, integration methods, and transmission channels. The regional power grids connected by renewable energy power stations are mostly in remote areas with relatively distributed loads. The regional power grids have longer transmission lines and the grid is relatively weak. Large-scale renewable energy collection, the cost of different collection methods is different, the impact on the stability of the power system is different, the corresponding protection measures, optimization methods are also different, and these problems need to be solved urgently. The characteristics of the power grid itself are the decisive conditions for determining whether the system can operate stably after the renewable energy grid integration. Under normal condition, the centralized connect to renewable energy is at the end of the grid, which is a typical weak connection system. According to the actual operating experience of renewable energy, the voltage stability of renewable energy power stations is strongly correlated with reactive power. On the one hand, the configuration of the reactive power regulating device in the system is insufficient, and the system loses its ability to control the voltage due to the exhaustion of the reactive power reserve, resulting in voltage instability. On the other hand, the non-global control of each reactive power source device in the system, and the adjustment limit of the discrete equipment gear position increase the reactive power loss of the long-distance transmission line, so that the area requiring reactive support cannot obtain the reactive power supply, it can also cause voltage instability. Therefore, the voltage stability reduction or voltage collapse caused by centralized connect of renewable energy is intrinsically consistent with the cause of voltage instability of conventional power systems. Based on the theoretical study of the stable operation of renewable energy connected to the grid, this paper uses the method of calculating the renewable energy development capacity based on the effective short-circuit ratio, and calculates the effective short-circuit ratio of the nodes that can be connected to the renewable energy power station. The recommended scheme of grid-connected network shows the correctness of the model and analysis method established in this paper.