Influence And Countermeasures Of Small Hydropower Station On Relay Protection Of Dong Ning Distribution Network

With the development of China's economy,the demand for electric power resources in our country is increasing.From the scientific research to production,from industry to agriculture,from cities to rural areas,from national construction to people's lives,the application of electric energy will be more extensive.The relay protection of the power system is a kind of protection system set up to maintain and ensure the safe operation of the power grid.As the relay protection of the distribution network,it is the protection device of various equipments inside the distribution network system.Through these relay protections,the stability of the power system of the distribution network can be guaranteed to ensure the safe operation of the system.Small hydropower belongs to non-carbon clean energy.It has neither the problem of depletion of resources nor pollution to the environment.It is an indispensable part of China's strategy for sustainable development,and then small-scale hydropower grids will provide distribution protection relays.Some technical problems,after the SHP access,not only make the distribution network from a single power supply to a multi-terminal power supply,but also change the level of faults in the nodes and lines near the small hydropower station,bringing new challenges to traditional distribution network protection.This article complies with the idea of extending “equipment safety” in power system operation to “substation safety in distribution network”.Combined with the constitution and construction characteristics of small hydropower generating units accessing to the power transmission and distribution network system,several forms of traditional relay protection and automatic reclosing are explained,and the current three-phase protection is compared and analyzed;After the Dongning distribution network,the impacts caused by systems such as current protection,distance protection,and access line reclosing of the original distribution network are compared and analyzed,and corresponding rectification measures are given for the impact;Through MATLAB simulation,small hydropower units connected to power transmission and distribution network systems are verified under different conditions,such as access to power transmission and distribution network feeders at different locations,different fault point locations on feeders,and different capacity of small hydropower units.The impact of the unit on the feeders,adjacent feeders,and the relay protection devices present in the entire transmission and distribution network system,and re-setting the relevant relay protection settings based on specific values.Finally,the self-adaptive protection of the small hydropower generating units before and after accessing the distribution network is analyzed,which provides a theoretical basis for relay protection of the small hydropower distribution network in the region.