Key technologies of optimization and control of DC micro-grid for drainage equipment of CBM well

In recent years, the Chinese government has vigorously promoted the coalbed methane (CBM) exploration and development action plan, effectively promoting the rapid development of CBM industry.On the one hand, the current AC-based power supply network for CBM surface drainage accounts for more than half of the production cost of electricity, which greatly restricts the sustainable development of CBM industry.On the other hand, DC micro-grid has become the development trend of micro-grid in the future because of its advantages such as simple control mode, fewer energy conversion links, no existence of reactive power and frequency stability.To solve the serious problem of power consumption in the current AC power supply network for CBM surface drainage, the DC transformation of power supply network for CBM surface drainage was proposed in this paper.Firstly, the reactive power compensation devices applied to the power supply network for CBM surface drainage and the energy-saving ways of the drainage equipment motor in CBM well under the periodic dynamic alternating load characteristics were reviewed.Secondly, based on the establishment of DC micro-grid including distributed energy resources (DERs), energy storage units and the drainage equipment in CBM well, the key technologies of optimization and control of the DC micro-grid for the drainage equipment of CBM well were emphatically expounded in terms of topological structure, optimal configuration, model establishment, voltage stability control and coordinated operation.Finally, from the aspects of key technological progress including the interaction between topological structure and system optimal allocation, system stability criterion under bidirectional energy flow and voltage stability control considering source-network-load coupling were analyzed, and the future development and application of the DC for the drainage equipment of CBM well was also given.It was pointed out that the progress of related key technologies can provide a scientific basis and theoretical guidance on the DC micro-grid for drainage equipment of CBM well.