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This article mainly studies the characteristics of transformer inrush current and the influence of different factors on transformer inrush current. This article states the background and significance of the inrush current, introduces the research status of the inrush current and the suppression technology. The suppression of the inrush current is the root of the problem. The mechanism of the inrush current is derived mathematically from the magnetic flux relationship, and the characteristics of the inrush current are analyzed through its related waveform diagrams. On this basis, the harm of inrush current is introduced. The core method is based on the PSCAD simulation platform to build the inrush current and the circuit to suppress the inrush current, and to set the parameters for simulation model. This article discusses the effects of transformer capacity, closing angle, knee voltage and basic parameters on inrush current.

With the development of intelligent substation, substations rely more on network communication to transmit substation information. High substation automations with reliable communication avoid the traditional complicated operation which needs to be done manually, and improve the efficiency of substation operation. But higher requirements for the reliability of information integrity are put forward. The protection setting of intelligent substation directly affects the correctness of the protection devices (Intelligent Electronic Device) and further affects the normal operation of the entire power system. Because the protection setting of protective devices is affected by power system operation mode, season climate and many other factors, the protection setting often needs to be adjusted. When the number of protection devices in substation is increasing rapidly, the frequent change of the protection setting can easily cause the missing or omission of protection setting for certain protection devices, resulting in the potential danger of the power system. On view of the above problems, combined with the development trend of IEC61850, this paper focuses on the on-line management of protection devices. By studying the data attribute of the online management of protection device settings and combining the layered network structure of the intelligent substation, the online management system for protection device settings is constructed, with the aim to eliminate the hidden danger caused by the missing or omission of protection setting.

For power grids with abundant small hydropower in China, the efficient switching process between small hydropower and distribution network will help to reduce the user outage time and the cutting of hydropower and load. This paper mainly adopts the simulation method combined with the regulation characteristics of small hydropower in rural areas. And the paper focuses on the amplitude and frequency characteristics of the initial stage of small hydropower. Firstly, the operation characteristics of small hydropower plants are studied, and the simulation model is built. Next, we study the amplitude frequency characteristics of small hydropower stations with better control capability such as leading phase operation. Further, in view of the large number of small hydropower stations with no phase operation capability in the rural power grid, we studied the simulation in the initial stage of the isolated network. By comparing and analyzing the operation characteristics of small hydropower stations at different initial stages under different conditions, it can provide support for small hydropower stations to reconnect into distribution network as soon as possible. This will help to reduce the tedious and long process of grid connection in the rural power grid.