废弃矿井残余煤层气开采多能互补直流微电网关键技术及瓶颈问题

Key technologies and bottlenecks of multi-energy complementary DC microgrid for residual coalbed methane drainage in abandoned mine

从废弃矿井残留能源与空间资源协同利用出发,在废弃矿井绿色低碳多能互补体系框架下,统筹考虑废弃矿井采空区煤层气开采活动用电需求与采煤沉陷区可再生能源发电潜力,以及低浓度瓦斯发电和储能作为补充,提出探索构建集成风-光-气-储的废弃矿井残余煤层气开采多能互补直流微电网系统。相较于普通直流微电网,低系统惯量、弱电网连接、分布式发电随机波动和周期变工况负荷大扰动等多重不利因素叠加使得废弃矿井残余煤层气开采多能互补直流微电网系统稳定运行面临更加严峻的挑战。为此,有必要围绕废弃矿井残余煤层气开采多能互补直流微电网系统这一废弃矿井残留能源与空间资源协同利用潜在场景涉及的关键技术及背后的瓶颈问题展开系统梳理与探讨。首先,阐述了废弃矿井残余煤层气开采多能互补直流微电网系统的拓扑结构与组成单元,并从能量流动模型出发探讨了在寻求系统容量优化配置过程中需要考虑的约束条件。接着,提炼出煤层气抽采机电动机周期变工况负荷分析、低浓度瓦斯发电机气-电转换环节耦合、电压稳定控制及协调运行等破解废弃矿井残余煤层气开采多能互补直流微电网系统可靠稳定及协调运行难题涉及的关键技术,总结和回顾了已有研究进展,分析了目前工作存在的难点和问题,同时探讨了可能的解决方法及后续工作建议。进一步指出亟待攻克低浓度瓦斯发电机气-电耦合长时间尺度与风光储短时间尺度联合建模,以及低惯量、弱连接、大扰动等多重不利因素作用导致的电压振荡机理等关键技术背后的核心瓶颈问题。最后,从已有工作基础、研究进展及经济效益评估等方面展望了构建废弃矿井残余煤层气开采多能互补直流微电网系统的可行性及应用前景。

In terms of the collaborative utilization of residual energy and space resources in abandoned mines,under the framework of a green low-carbon multi-energy complementary system,a multi-energy complementary DC microgrid integrating wind-solar-gas-storage for residual CBM drainage in abandoned mine was proposed and constructed with the consideration of both the electricity demand of coalbed methane(CBM)in the abandoned mine goaf and the power generation potential of renewable energies in coal mining subsidence areas,as well as the low-concentration gas power generation and energy storage as supplements.Compared with the common DC microgrids,the superposition of multiple unfavorable factors such as low system inertia,weak grid connection,random changes in distributed power generation and large fluctuations in periodically variable working condition load makes the stable operation of the multi-energy complementary DC microgrid for residual CBM drainage face become a more severe challenges.Therefore,it is necessary to systematically discuss and investigate the key technologies and bottlenecks involved in the multi-energy complementary DC microgrid for residual CBM drainage in abandoned mine which is a potential scenario of collaborative utilization of residual energy and space resources in abandoned mines.First,the topology and components of a multi-energy complementary DC microgrid for residual CBM drainage were described,and the constraints that need to be considered in the system capacity optimization were discussed based on an energy flow model.Then,the key technologies including periodically variable working condition load analysis of CBM pumping motor,coupling of gas-electric conversion link of low-concentration gas generator,voltage stabilization control and system coordinated operation involved in achieving reliable,stable and coordinated operation of multi-energy complementary DC microgrid for residual CBM drainage in abandoned mine were concluded.The recent research progresses were summarized and reviewed,the difficulties and problems existed in the current work were analyzed,and some possible solutions and suggestions for following work were discussed.Furthermore,it is pointed out that it is urgent to address the bottleneck issues behind the key technologies such as the joint modeling method of both gas-electric coupling long-time scale of the low-concentration gas generator and short-time scale of wind-solar-storage,as well as the bus voltage oscillation mechanism caused by multiple unfavorable factors such as low inertia,weak connection and large disturbance.Finally,the feasibility and application prospect of constructing a multi-energy complementary DC microgrid for residual CBM drainage in abandoned mine were prospected from the aspects of existing work basis,research progress and economic benefits assessment.