Distributed Generators (DG) has the advantages of less pollution, high energy utilization efficiency, and flexible installation locations. It is an important form of new energy utilization. However, DG has shortcomings such as intermittent output, randomness, and difficulty in control. Decentralized grid connection brings great difficulties to system operation. This is also the main technical bottleneck facing the promotion and application of DG at present. Microgrid is an autonomous system composed of DG, loads, energy storage systems and control devices that can realize self-control, protection and management. It can be connected to the grid and can operate on an island. It is an internationally recognized solution to the problem of large-scale connection of DG to the power grid. The main way. However, microgrids and traditional grids are essentially different in terms of generator management, control methods, equipment and system integration. Power supply types and grid-connection forms are diverse, operating modes are changeable, system inertia is small, anti-interference capabilities are poor, and DG and load are present. Double fluctuations have higher requirements for the dispatch and control of microgrids. At the same time, conventional grid-connection switches have a long time to open. When switching between microgrid grid-connection and islanding modes, it is extremely difficult to ensure uninterrupted power supply. The main innovations of this project are as follows:
1) A microgrid voltage and frequency control method based on sliding mode compensation control is proposed for the first time
A new load disturbance observer is designed to estimate the load value. A dual sliding mode compensation controller is proposed for the first time to smooth and optimize the DG output and adjust the exchange power with the external network, making it easier to achieve power instantaneous balance when the microgrid suffers from large disturbances. This not only makes innovations in the control algorithm, but also makes the DG more actively participate in the frequency modulation and voltage regulation control of the microgrid, improving the robustness and anti-interference capabilities of the microgrid.
2) It took the lead in developing an intelligent fast switching system to achieve smooth and off-grid switching of the microgrid
Applying vacuum permanent magnet technology to microgrid switches, we have taken the lead in developing a microgrid intelligent fast switching system, which is applied to the connection between the microgrid and the large power grid. It can quickly remove faults within 10ms after a fault and switch to islanding operation. state, effectively ensuring the smooth transition of the microgrid between grid-connected/islanding modes, and ensuring the reliable and continuous power supply of the load within the microgrid.
3) Innovatively proposes an integrated microgrid energy optimization and dispatch strategy of "source-grid-storage-load" under multiple time scales
A shiftable load model is established, and a multi-time scale source-grid-storage-load microgrid energy management and optimal dispatch strategy is innovatively proposed. In the day-ahead scheduling strategy, the probability distribution of random variables generated by source load fluctuations is serialized to model the random variables in the microgrid based on sequence operation theory, taking into account the impact of uncertainty on large time scales; in real-time scheduling, a moving average filtering method based on composite energy storage is proposed to reasonably allocate fluctuating power in composite energy storage, thus solving the impact of uncertainty on system optimization and scheduling at small time scales.
4) A comprehensive evaluation system for microgrid planning and operation based on multi-factor analysis has been constructed.
Comprehensively considering the planning, construction, operation and maintenance costs of the microgrid and long-term operating indicators, a microgrid evaluation system including factors such as economy, adaptability, safety, environment and sensitivity is constructed to provide a good evaluation system for the planning and operation of the microgrid.
The project has obtained 10 patent authorizations (6 invention patents and 4 utility model patents), applied for 12 invention patents, and published 42 papers (26 papers included in SCI /EI). The added output value is 210 million yuan and the added profit is 32.5769 million yuan. The project has been accepted by the expert group, and the overall level has reached the domestic leading level. Some results have outstanding substantive characteristics and significant progress after being newly searched. The results have been promoted and applied to more than 10 microgrid engineering projects in Shanghai, Zhejiang, Jiangsu, Beijing, and Hebei, and have been widely praised.
The implementation of this project has achieved breakthrough progress in microgrid technology, laid a solid technical foundation for the large-scale development of my country's microgrid technology, and made positive contributions to promoting the distributed utilization of clean energy in my country and implementing energy conservation and emission reduction.