Energy storage current transformer grid connection and grid disconnection seamless switching device and method

Abstract

The invention relates to an energy storage current transformer grid connection and grid disconnection seamless switching device and an energy storage current transformer grid connection and grid disconnection seamless switching method. The energy storage current transformer grid connection and disconnection seamless switching device is connected with a power grid monitoring system and a grid connection point switch, and comprises an energy storage current transformer, a controller, a battery management system, a battery pack and a first transformer, wherein the controller is connected with the power grid monitoring system, the energy storage current transformer and the battery management system, the battery pack is connected with the energy storage current transformer and the battery management system, the energy storage current transformer is connected with a first power grid bus through the first transformer, the controller is provided with a first interface connected with a voltage transformer, a second interface connected with the grid connection point switch and a third interface connected with a grid connection point switch position node, and the voltage transformer is arranged above the grid connection point switch. Compared with the prior art, the energy storage current transformer grid connection and grid disconnection seamless switching device and the energy storage current transformer grid connection and grid disconnection seamless switching method have the advantages of being capable of achieving high precision synchronism of grid disconnection to grid connection switching, achieving smooth grid connection to grid disconnection switching, being independent of a communication network and the like.

Description

technical field [0001] The invention relates to the field of micro-grid control, in particular to an energy storage converter and an off-grid seamless switching control device and method. Background technique [0002] Large-scale energy storage technology is a cutting-edge technology. At present, only a few developed countries such as China, the European Union, and the United States have carried out research on this technology and achieved certain research results. However, many technical bottlenecks have not yet been broken through. Some domestic universities, scientific research institutes and equipment manufacturers have also begun to carry out related research on energy storage converters and off-grid seamless switching, and the technical routes are different, and the technology is immature in engineering application, mainly in the following aspects Outstanding issue: [0003] 1) When the energy storage converter is connected to the grid and switched to off-grid operati...

AI Technical Summary

Problems solved by technology

[0003] 1) When the energy storage converter is connected to the grid and switched to off-grid operation, it is impossible to realize the load without power loss and there is a large voltage fluctuation at the moment of off-grid startup;

[0004] 2) When the energy storage converter is switched from off-grid to grid-connected operation (especially when it is switched to weak grid operation, such as diesel generators), it cannot smoothly switch to impact the grid, resulting in failure of the weak grid, and the energy storage converter carried by the energy storage converter The battery generates an instantaneous high current shock;

[0005] 3) The energy storage converter itself cannot complete the automatic synchronization function, and the off-grid switching is heavily dependent on the synchronous detection and control accuracy of the configured on-grid and off-grid control device;

[0006] 4) When the grid-connection point switch is not a high-speed electronic switch, due to the inconsistency of each action time of the switch and the long return time of the switch position node, it is impossible to accurately predict the closing time point of the switch, which will cause impact on the grid and The energy storage battery attached to the energy storage converter produces an instantaneous high current impact;

[0007] 5) The energy storage converter relies heavily on the communication network to transmit information such as the voltage amplitude and phase angle of the grid at the grid-connected point during the off-grid to grid-connected synchronous process

[0009] 1) The synchronous control accuracy of the off-grid switching device is poor, resulting in the inability of the energy storage converter to switch smoothly from off-grid to grid-connected, impacting the power grid, causing a weak grid failure, and causing an instantaneous high current impact on the energy storage battery of the energy storage converter ;

[0010] 2) After the on-grid and off-grid switching device separates and merges the outlet switch, the time delay in judging the switch position is long, which will also cause impact on the on-grid and off-grid switching, and seamless switching cannot be achieved;

[0011] 3) When the consistency of the switch action time of the grid-connected point and the return time of the position node is poor, it will also cause impacts in the grid-connected and off-grid switching process, and seamless switching cannot be achieved;

[0012] 4) The on-grid and off-grid switching device transmits information such as the voltage amplitude and frequency of the on-grid point to the energy storage converter through the communication network. When switching on and off the grid, the real-time communication cannot be guaranteed, which will also cause currents in the on-grid and off-grid switching. Shock, unable to achieve seamless switching;

[0013] 5) The existing on-grid and off-grid switching is completed by the cooperation of the on-grid and off-grid switching device and the energy storage converter, the real-time control is poor, and the cost is high

Images