【作者】 雷之力；

【导师】 艾欣；

【作者基本信息】 华北电力大学（北京） ， 电力系统及其自动化， 2011， 博士

【摘要】 微网是一个集中了发电装置、储能装置、控制设备和用户负荷的发配电网络,也是具备智能化基础和一定独立运行能力的低压有源供电网络。从技术发展的角度,微网是分布式发电技术向配电网络渗透的最新阶段,也是建立智能电网的重要基础,更是解决现代电力系统在保证供电与保护环境之间所面临尖锐矛盾的关键环节。所以如何更好地发挥微网接纳新能源发电和可再生能源发电能力,确保微网在引入电力系统后不出现严重的电能质量危害,不仅是迫切需要解决的技术问题,也是微网技术能够实际得到推广应用的基本前提。本文围绕谐波谐振和电压暂降这两个微网电能质量的关键问题,从传统电力系统中这两个问题的研究成果出发结合微网接入带来的新变化和新特点对微网谐波谐振和电压暂降的危害形式和产生机理作了细致的分析,并提出了评估控制微网谐波谐振和电压暂降的新方法,研究的主要内容和取得的主要成果有：提出了用于评估微网及其所在配电网串联和并联谐波谐振的模式评估法。所提方法可以准确把握包括逆变器参与谐振在内的微网谐波谐振的发生频率、谐振激发程度,以及激发谐振的位置。相比传统谐波谐振评估方法,新方法不仅可以同时评估串联和并联两种谐振,而且还能评估逆变器在谐波谐振中的特殊作用。因此新方法用于微网谐波谐振评估有着非常明显的优势。指出微网中串、并联两种电压补偿方法间存在功率线性耦合关系,并据此提出微网电压暂降联合补偿法。新方法能够充分利用微网分布式电源多、并联电压补偿能力强的特点,协调串联和并联两种方式对微网中出现的电压暂降进行补偿,避免了传统方法中串联补偿器有功输出容量对微网电压暂降补偿能力的约束。相比同类方法,新方法的另一大优点是不需要在补偿设备的直流母线间建立电气联系,避免了可能给设备安装位置带来的约束,显著扩展了参与电压暂降补偿的设备种类和数量。揭示了微网并联电压补偿方式输出功率过高的机理,指出过小的联络线阻抗是根本原因。提出了基于限流器的并联电压暂降补偿方法。相比传统方法,新方法的主要优点是并联电压补偿器能够以合理的输出功率独立承担电压暂降补偿任务。新方法的另一个优点是,限流器只负责约束电流维持电压无需对外输出功率。新方法能够最大限度地利用微网中分布式电源的电压暂降补偿能力。更多还原

【Abstract】 Microgrid is an electric power generation and distribution network, which is consisted by generators, energy storage units, control facilities and consumers’loads. Microgrid is also a low voltage active power providing network with excellent capability of accommodating smart operation modernization and certain ability of isolated operation. In the aspect of technology evolution, microgrid is a new stage of the way of distributed generation penetrating into the distribution network, and critical step to establishing the Smart Grid, and solving the critical problem of how to provide increasing load with enough electric power and low environment harming effects. Therefore, it is very important technical problem needed to be solved that microgrid connection would bring no unacceptable power quality compromising into distribution network. And the problem is the precondition of take fully advantage of microgrid in accommodation of renewable energy power generation and new energy power generation. The two important power quality problems, harmonic resonance and voltage sag, are investigated in this dissertation, from the angles of both formation mechanism and harm mode. The investigation is based on the conclusions of investigations in this two power quality problems in conventional power systems, and conducted with fully awareness of the changes and new features brought by microgrid connection. According to the investigation results, the new methods of harmonic resonance assessment and voltage sag compensation in microgrid are proposed, and the main contents and related conclusions are outlined as follows:The harmonic resonance modal assessment methods for both series and parallel harmonic resonance happening in microgrid and distribution network are proposed. The proposed assessment methods are based on the modal analysis results of node admittance matrix and fundamental circuit impedance matrix. According to the results, assessment indices can be produced and than harmonic resonance frequency, fierce degrees of inspired harmonic resonance, and the places of most fierce resonance can be inspired would be all discovered. Contrast to conventional methods, the ability of assessing series and parallel harmonic resonance simultaneously and of the special resonance effects inverters makes in microgrid is the big advantage of implementing proposed method in microgrid harmonic resonance assessment.The existence of connection between the output power of series and shunt voltage sag compensation is discovered, as well as linearity between the power reduction of series compensator and power generation of shunt compensator. Therefore, the combined compensation method for voltage sag in microgrid is proposed. In contrast to the conventional methods, the advantages of new method includes making fully use of distributed generation units and other components with shunt voltage compensating capability, compensating voltage sag simultaneously in series and shunt ways, lesser constrain on microgrid voltage sag compensating capability improvement and more independence on active power output capacity of series compensator, lesser constrain on location of series and shunt compensator and far more available compensating components to be chosen by eliminating the connection line between the DC bus of the compensators.The mechanism of excessively high output power phenomena of shunt voltage sag compensation in microgrid is discovered, and the reason that relatively too small quantity of connection line between microgrid and distribution network contrasting too large quantity of line voltage makes large compensation current and power is confirmed. According to the discovered reason, the current limiter based shunt voltage compensation method is proposed. In contrast to conventional voltage sag compensation method, the proposed method has the advantages on acceptable output power of shunt compensator that compensating voltage sag independently, only with the assistance from current limiter by maintaining voltage and producing no output power. The new method can exploit the maximum voltage sag compensating capability in microgrid by all distributed generation units and energy storage device be able to mitigate voltage sag directly.更多还原