Search

In this paper, a small hydropower microgrid solution with high applicability is proposed to solve the problem of high line failure rate and long maintenance time, which can improve the reliability of distribution network in mountainous areas. In this scheme, small hydropower and local load constitute a low-cost but efficient microgrid operation to improve the reliability of rural electricity. In this scheme, small-sized hydropower and local load constitute microgrid operation. In case of failure, the scheme makes full use of the independent operation of microgrid to provide qualified power quality to local load. This scheme is easy to realize and does not need additional energy storage, so it has good economy. Firstly, the frequency disturbance characteristics of small hydropower microgrid is analyzed, which lays a theoretical foundation for small hydropower microgrid operation. Then it introduces the island operation mode to grid-connected operation mode transition of small hydropower, including the key technologies such as frequency adjustment strategy in island operation stage. Finally, the simulation studies show the effectiveness of the method.

As the largest global renewable source, hydropower is a useful supplement to mountainous distribution networks with abundant water resources, and shoulders a large portion of the regulation duty in many power systems. In particular, in the form of decentralized energy sources located to their customers, small hydropower (SHP) improve grid stability by diversifying the electricity system and reducing power loss. The mountainous distribution networks supplied by small hydropower are closed-loop design but open-loop operation, which easily causes the tripping of tie line even further the off-grid operation of small hydropower system. Once the tie line trips, the current countermeasures&mdash, such as hydropower shutdown and load shedding&mdash, do not fully guarantee the reliability of power supply and the utilization efficiency of hydropower. This paper studies the amplitude-frequency characteristics of SHP off-grid, according to the typical integration of hydropower in South China, a SHP on-grid/off-grid model is established based on the Power Systems Computer Aided Design (PSCAD) platform. It is found that due to the inertia of SHP, the amplitude-frequency characteristics of SHP island system are relatively slow, and the process of non-synchronization with the main grid is gradually expanded. The characteristic of SHP has a certain degree of synchronization with the main grid in the initial island operates stage, which helps to find a novel grid connection method. This paper further proposes the strategy of using fast busbar automatic transfer switch (BATS), which quickly connect the trip-off SHP to the distribution network under the condition of permitting distributed energy grid-connected. The PSCAD simulation results show that proposed strategy has a limited impact on the power grid and prove the effectiveness of the method.

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.