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分布式发电接入电力系统若干问题的研究

Research on Power System with Penetration of Distributed Generators

【作者】 陈琳

【导师】 甘德强; 钟金;

【作者基本信息】 浙江大学 , 电力系统及其自动化, 2007, 博士

【摘要】 在电力市场环境和可持续发展战略影响下,分布式发电技术以其独有的安装灵活、供电方便、环保等特点引起全球范围内的关注。在集中式发电和大电网基础上,大力发展分布式发电(Distributed Generation,DG)技术,建立混合型网络成为未来电力系统发展的必然趋势。因此,全面了解不同类型分布式发电技术,对分布式发电接入电力系统合理规划,研究其在电力系统应用和影响具有重要的理论意义和实践价值。本文在概述了不同类型分布式发电技术特点基础上,对联网DG混合电力系统规划运行、DG在电力系统中辅助服务和可靠性方面应用、DG对系统运行负面影响及解决方案进行了深入研究。主要研究成果如下:1)针对分布式发电与大电网联合供电发展趋势,建立了联网分布式发电系统规划模型。根据各种输电网情况:输电网全年正常运行且电价固定、考虑输电网停运状态、输电网实时电价,应用启发式算法得到了对应情况下联合系统最优供电方案,讨论了各种因素对DG选型、容量配置等优化结果的影响。根据负荷曲线和各类型分布式能源资源分布数据,得到了不同类型DG和输电网小时功率输出运行结果。规划结果和运行性能充分说明了分布式电源之间及其与输电网联合供电的经济、可靠互补优势,为DG成为可行的电网扩容计划提供了理论论证,并对实际含分布式发电配电系统规划提供了重要的指导意义。2)辅助服务市场正在建立和发展,本文讨论了分布式发电提供AGC辅助服务的潜力。通过引入“微型电网”概念,在配电系统范围内建立了含分布式发电系统AGC调度模型。模型求解得到了DG参与AGC辅助服务市场前后AGC调度分配结果,结果显示了分布式电源参加AGC服务的经济性能;在选择控制参数优良的分布式电源类型后,频率,非计划交换电量响应仿真结果说明了DG提供AGC服务的技术优势以及发电机类型对AGC运行性能的影响。进一步,基于不同类型机组对控制性能指标——区域控制偏差(ACE)的贡献系数,提出了对AGC辅助服务费用简单直观的比例分摊方法,在一定程度上体现了市场环境下费用分摊的公平性。3)在电力市场环境,用户对配电系统可靠性要求日益提高的情况下,提出了DG作为配电系统故障下的备用机组应用。通过权衡比较购买DG备用费用增加和负荷中断费用减少,得到了最优容量配置。其中,购买备用费用计及了因机组自身FOR造成的失机组损失费用;可中断费用根据不同负荷类型停电损失函数(SCDF)精确得到。算例显示该模型具有较好的经济效益,DG备用容量满足了不同负荷类型的可靠性需求,极大减少了传统统一可靠性指标下的备用交叉补贴。通过计算DG做后备机组前后负荷点可靠性指标和系统中断费用,结果说明DG能够有效降低可中断费用、缩短负荷点平均停运时间和停运持续时间,并对靠近DG的负荷可靠性影响更大。4)风力发电机等可再生能源发电接入系统比例逐年增加,针对风力发电随机波动引起的电压波动问题,建立了系统无功设备最优改造计划。通过引入静止无功补偿器(SVC),配电网已有柴油发电机作为快速补偿设备,根据蒙特卡罗仿真得到的各种风力发电状态,确定了SVC最优安装位置,各无功源最优出力。仿真算例表明,风力发电机具有功率输出随机,发出有功同时消耗无功功率特点,通过安装足够的SVC容量,可以大幅度降低系统网损和电压偏差,达到克服电压波动,提高系统电能质量目的。5)针对风力发电机接入系统引起的无功支持费用分摊问题,采用基于公理的Shapley值分摊方法实现了无功服务费用在不同风力发电机组间的分摊。该方法满足了经济学公理特征,分摊结果公平、合理,易被市场参与者接受,对风力发电机合理的接入位置和容量提供了经济信号,对分布式发电机联网收费问题提供了解决方案。

【Abstract】 Distributed generation (DG) has been widely used in the deregulated electric power systems for its immense benefits. Studies of distributed generation and its application in electric power system become more important to utilize DG efficient and refine power system operation. Based on the introduction of various types of distributed generators, a systematic study on planning for grid-connected distributed generation system, the potential of DG providing ancillary service, the backup generation application, negative impacts of DG on power system and its control strategy is carried out in this dissertation. Contributions are summarized as follows,1) Following the trend of developing grid-connected distributed generation system, an optimal generation expansion planning model is presented in this paper. The system optimal results and operation performances under various transmission system scenarios are determined by using heuristic method. Effects of transmission system outage indexes, real time price and randomness of renewable generation resource on the system design are discussed. Optimal results and hourly system operation performance suggest the advantages of grid-connected distributed generation system. They also provide guide for expansion planning of distribution system with DG.2) The potential benefits of DG providing ancillary services are discussed. By introducing "microgrid" concept, a novel AGC dispatch model in distributed system is proposed. By comparing the optimal AGC dispatch results in the two cases with and without DGs, the economic prominence of DG to provide AGC services is discussed. By selecting DGs with good regulation characteristics, simulations to frequency and inadvertent interchange are performed. The results indicate the technical feasibility of DG to provide AGC services too. Based on the contribution of generators to the Area Control Error (ACE), the cost of AGC services is allocated by a transparent proportional method.3) Distribution system reliability becomes important in electric power market. This paper introduces DGs as backup generators in distribution system. The optimal reserve procurement model aims to balance the interruption cost and reserve purchased cost. The effect of Forced Outage Rate (FOR) of distributed generators is included in reserve purchase cost, while the interruption cost is calculated accurately according to the Sector Customer Damage Function (SCDF) of different types of load. Case studies show that the model increases the economic benefits and decreases the crossover subsidy of reserve caused by some traditional reserve procurement method. The optimal results suggest DG can improve load and system reliability effectively, especially for those loads near DGs.4) With the numbers of wind power generators increasing rapidly, they may cause voltage variations due to the random-like outputs of wind turbines. To solve this problem, we introduce Static Var Compensator (SVC) into distribution systems, and combine the reactive power support from distributed diesel units for voltage control. An optimal reactive power planning model is proposed in this paper. Monte-Carlo simulation is used to simulate the uncertainty of wind power generation. The locations and the outputs of SVCs and distributed diesel units are determined by hybrid encoding genetic algorithm. Case studies show WPG has characteristics of generating active power randomly and absorbing reactive power at the same time. By installing enough capacities of SVC, the system loss and voltage deviation can be reduced significantly.5) Since the main purpose of installing SVCs is to regulate the voltage variations caused by wind turbines, a shapley value criterion based on cooperative theory is proposed to allocate the reactive power support cost. The allocation result is equit and acceptable to all participants. It provides some economic signals to decision-makers to determine the appropriate locations of DGs and provides a new way to allocate some grid-connected cost caused by DG.

  • 【网络出版投稿人】 浙江大学
  • 【网络出版年期】2008年 04期
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