微电网系统建模的挑战—“智能微电网与可再生能源系统的关键技术”专题(前言)
Modeling challenges for microgrids system

微电网系统是由负荷、分布式电源、电力电子变换器通过电气网络紧密集成的可控供电系统,逐渐成为我国城镇化进程中重要的一种供电模式。典型微电网系统通过电力电子变换器接入多种分布式电源,其中风、光等分布式可再生能源接入比例较大,这些发电单元大幅度随机变化、各单元动态特性各异、不同单元的变化呈现多个时间尺度,使得微电网系统的整体建模与稳定特性分析面临巨大挑战。由于目前无法在数学上精准建立随机大干扰环境下微电网系统的动态模型并确知其稳定控制域,在实际微电网工程中,一般会配置较大容量的储能以确保微电网系统在各种运行工况下的稳定性。在此基础上,针对每个具体的微电网工程建立仿真系统以确定其稳定控制策略,导致微电网工程的实现成为个性化的经验式解决方案。因此,对微电网系统进行精准的动态建模已迫在眉睫。本文针对典型微电网系统架构进行精准暂态建模的探索,对其中的典型发电单元进行独立的动态建模,对微电网系统中多个发用电单元不同的时间响应特性进行了描述,针对微电网系统整体建模这一挑战,给出在外界随机扰动、多时间尺度特性、稳定域求解等几个方面所进行的思考,期待业内的专家学者为微电网工程应用中的精准动态建模问题给出建议和解决方案。
Microgrid, composed of load, distributed power supply and power electronic converter, is closely integrated into a controllable power supply system through the electrical network. The microgrid system gives solutions to interface distributed generation including wind, solar and other renewable energy, through power electronic converters. In a microgrid, different generation units have different dynamic characteristics, and appear to have multi-timescales feature, which bring huge challenges on the overall modeling and stability analysis of microgrid. In the practical microgrid engineering, it is usually equipped with a large-capacity energy storage system to ensure the stability under various operating conditions, because it is impossible to establish the mathematical dynamic model for microgrid under the environment with large random disturbances at present. In this situation, each practical microgrid system is obliged to establish a simulation model specially to determine the stability control strategy, with the result that the microgrid engineering relies on personalized customization and historical experience. Therefore, accurate dynamic modeling is extremely necessary. This paper studies the accurate transient modeling of the microgrid with a typical architecture, in which independent dynamic models for different distributed generations are established and the dynamic response characteristics of distributed generations are described in detail. In view of the challenge of overall modeling for microgrid, this paper put forward some reflections on external disturbance, multi-timescales, and stability control region solver, and we hope the experts and scholars could provide the recommendations and solutions on accurate dynamic overall modeling for microgrid.