主动配电网与微电网分层协调电压控制

发布时间：2018-03-29 20:42

本文选题：分布式电源　切入点：微网　出处：《山东大学》2017年硕士论文

【摘要】：当前,全球能源紧缺及环境污染日益严峻,具备一系列优势的分布式发电技术逐步崭露头角。为应对常规配电系统的结构及运行策略与分布式电源(distributed generation,DG)大规模接入的矛盾,既能提高DG利用效率又能保证供电可靠性的微电网技术应运而生,在逆变型并网DG基本控制方法及微网典型控制模式基础上,从并网DG(光伏系统)、多个DG组成的微网、多个微网并网运行组成的系统三个层面对并网点电压就地控制策略及分层协调电压优化控制方法进行了分析研究。随着相关技术发展,配电网络中DG渗透率日渐升高,光伏等通过逆变器并入电网的DG均具有一定的无功容量,可以向电网提供无功支撑,鉴于电力系统可靠性及稳定性要求,光伏电源参与并网点电压控制备受关注。论文基于传统的逆变器控制方法,从外环控制器设计的角度,有功功率外环设定为恒有功功率控制方式,无功功率外环设定为恒压控制方式,利用光伏无功功率实现对并网点电压的稳定控制。当光伏有功设定值接近最大功率时,其无功输出能力将受到容量制约,为协调光伏有功、无功出力之间的矛盾,提出相应控制策略,当电压波动较大时,可适当减少光伏有功输出,优先满足调压要求。相较于简单并网的各类DG,微网运行方式灵活,即可以孤网模式运行,又可工作于并网状态。当微网并网时,配网需充分利用微网内部的各类DG参与自身的优化调度。论文借鉴"二级电压控制"的原理,将各个联络点(point of common coupling,PCC)作为主导节点,将微网在配网层面PCC点处等值为一发电机,其无功输出作为配网优化控制变量,配网优化给定PCC的电压参考值,并将此参考值作为微网优化模型的目标函数,将微网内各类DG所发无功纳入到优化控制变量中,与传统的控制策略相结合,协调微网层面各类无功源控制PCC点电压。当多个微网并网运行时,其将对配网的运行和控制产生一系列的影响,如果不考虑配微之间的交互协调优化问题,将可能导致部分技术问题。论文在已有研究的基础上,提出了一种配微协调优化控制方法,即采用"分解协调"的方法将全系统的优化控制问题分解为不同控制子区域的控制问题。首先将配微解耦,在配网层面,将微网等效为PCC点负荷注入,在微网层面,将配网等效为PCC点电压源,交替计算配微最优潮流。同时交互边界处的协调变量,即PCC点电压及功率值,进而实现配微优化控制的协调,实现了灵活性与协调性的统一。考虑全天不同时段光伏有功出力及负荷变化情况,算例仿真表明所提控制策略与求解算法的有效性。
[Abstract]:At present, the global energy shortage and environmental pollution are becoming increasingly severe, and distributed generation technology with a series of advantages is gradually emerging. In order to cope with the contradiction between the structure and operation strategy of the conventional distribution system and the large-scale access of distributed generation system (DGG), The microgrid technology, which can improve the efficiency of DG utilization and ensure the reliability of power supply, emerges as the times require. On the basis of the basic control method of inverter grid-connected DG and the typical control mode of microgrid, the grid-connected DG (photovoltaic system), which is composed of several DGs, is introduced. In this paper, the local control strategy of parallel network voltage and the method of hierarchical and coordinated voltage optimization control are analyzed and studied in three layers of the system composed of multiple microgrid operation. With the development of related technology, the DG permeability in distribution network is increasing day by day. The DG, which is incorporated into the grid by inverters, has a certain reactive power capacity, which can provide reactive power support to the power network. In view of the reliability and stability requirements of the power system, Based on the traditional inverter control method, the active power outer loop is set as the constant active power control mode from the point of view of the outer loop controller design. The reactive power outer loop is set as the constant voltage control mode, and the stable control of the parallel dot voltage is realized by using the photovoltaic reactive power. When the set value of the photovoltaic active power is close to the maximum power, its reactive power output ability will be restricted by the capacity, which is the coordination of the photovoltaic active power. According to the contradiction between reactive power and reactive power, the corresponding control strategy is put forward. When the voltage fluctuation is large, the active power output of photovoltaic can be reduced appropriately, and the voltage regulation requirement can be satisfied first. Compared with all kinds of DGs connected by simple grid, the operation mode of microgrid is flexible. When the microgrid is connected to the grid, the distribution network needs to take full advantage of all kinds of DG inside the microgrid to participate in its own optimal scheduling. This paper draws lessons from the principle of "two-stage voltage control". Each focal point of common coupling is used as the leading node, the microgrid is equivalent to a generator at the PCC point of the distribution network, its reactive power output is taken as the optimal control variable of the distribution network, and the voltage reference value of the given PCC is optimized by the distribution network. The reference value is taken as the objective function of the microgrid optimization model, and the reactive power generated by various DG in the microgrid is incorporated into the optimal control variable, which is combined with the traditional control strategy. Coordinated reactive power sources control the PCC point voltage at the microgrid level. When multiple microgrids are connected to the grid, it will have a series of effects on the operation and control of the distribution network. On the basis of the previous research, this paper proposes an optimal control method for matching microcoordination. That is to say, the optimal control problem of the whole system is decomposed into control problems in different control sub-regions by the method of "decomposition and coordination". Firstly, the microgrid is decoupled. At the distribution level, the microgrid is equivalent to the PCC point load injection, and at the microgrid level, the optimal control problem is decomposed into the control problem of different control sub-regions. The distribution network is equivalent to a PCC point voltage source, and the optimal power flow is calculated alternately. At the same time, the coordination variable at the interaction boundary, that is, the voltage and power value of the PCC point, is used to realize the coordination of the distribution micro-optimal control. The unity of flexibility and coordination is realized. Considering the variation of active power and load of photovoltaic at different periods of the day, the simulation results show that the proposed control strategy and the algorithm are effective.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM76;TM727;TM714.2

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