并网光伏发电系统无功电压控制研究

发布时间：2018-01-28 02:08

本文关键词： 并网光伏系统逆变器无功电压控制协调控制灵敏度　出处：《重庆大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着能源可持续发展战略的推进，光伏发电技术迅速发展，从基础科学的研究到工程实践，光伏发电俨然已成为当今电力科学中最为活跃的研究领域之一。由于光伏发电在电网电源中比例不断增大，围绕光伏并网问题的研究课题也越来越受关注。本文分析光伏并网点静态电压稳定性问题，通过懫取无功电压控制策略，改善并网点的电压稳定性，提高电网接纳光伏能力。根据装机容量与并网电压等级不同，并网光伏系统分为分布式光伏发电并网系统与大型光伏电站。本文首先分析了并网光伏系统有功、无功出力变化对并网点电压的影响，并网光伏逆变器应发出一定的无功功率支撑电网电压。并对系统内部单个逆变器的数学模型、向量图、无功出力极限等理论进行了分析，在两相静止坐标系下，建立单个逆变器整体控制框图，系统控制包括有功控制、无功独立控制、电流控制、电压畸变和不平衡时控制方法，，为后续并网光伏发电系统的无功电压控制研究奠定基础。在分布式光伏发电系统背景下，仅以并网逆变器作为灵活可控的无功源。从电网电压降落角度研究光伏发电接入电网前后并网点电压的变化，并深入分析了德国电气工程师协会提出的几种分布式光伏系统无功电压控制策略，在此基础上提出一种基于并网点电压幅值与光伏有功出力的Q(U,P)无功功率控制策略，在该控制策略下，光伏系统所有逆变器参与电网电压调节，在维持电网电压在要求范围的前提下，无功吸收总量最低，电网有功、无功损耗最小。在大型光伏电站背景下，以并网逆变器与无功补偿装置SVG作为无功源。本文首先详细介绍了大型光伏电站的实际模型，研究了大型光伏电站对电网电压静态稳定性的影响。再次，根据并网点电压幅值Q(U)策略整定光伏电站实时无功差额，进而在光伏发电单元与无功补偿装置之间协调分配，以维持并网点电压的稳态运行。为减小电站内部集电线路无功传输，降低功率损耗，无功控制中优先考虑无功补偿装置。当无功补偿装置满发时，将剩余无功功率分配给各光伏发电单元，光伏发电单元之间的无功分配结合了电压/无功灵敏度的分析，在灵敏度基础上确定了光伏发电单元的无功输出，由此提高了光伏电站的调压能力。本文详细分析不同类型并网光伏发电系统对电网电压静态稳定性的影响，并针对各自的结构特点对其进行无功电压控制，为提高光伏系统汇集地区系统的电压稳定性与增大光伏系统在电网中的渗透率奠定了理论基础和决策支持。
[Abstract]:With the promotion of sustainable energy development strategy, photovoltaic power generation technology has developed rapidly, from basic science research to engineering practice. Photovoltaic power generation has become one of the most active research fields in power science. In this paper, the static voltage stability of photovoltaic network is analyzed, and the voltage stability of parallel network is improved by taking reactive voltage control strategy. Improve the grid capacity to accept photovoltaic. According to the different installed capacity and grid-connected voltage grade, grid-connected photovoltaic system is divided into distributed photovoltaic generation grid-connected system and large-scale photovoltaic power station. Firstly, the active power of grid-connected photovoltaic system is analyzed. The influence of reactive power output on the voltage of parallel grid, the grid-connected photovoltaic inverter should issue a certain reactive power to support the grid voltage, and the mathematical model of a single inverter in the system, vector diagram. The theory of reactive power limit is analyzed, and a single inverter control block diagram is established in two-phase static coordinate system. The system control includes active power control, reactive power independent control and current control. The control method of voltage distortion and unbalance lays a foundation for the research of reactive power and voltage control in grid-connected photovoltaic power generation system. In the background of distributed photovoltaic generation system, only grid-connected inverter is used as a flexible and controllable reactive power source. Several reactive power and voltage control strategies of distributed photovoltaic system proposed by the German Electrical Engineers Association are analyzed in depth. On this basis, a QU based on the amplitude of the parallel dot voltage and the active power of the photovoltaic system is proposed. Under the control strategy, all inverters of photovoltaic system participate in the regulation of grid voltage, under the premise of maintaining the grid voltage in the required range, the total amount of reactive power absorption is the lowest, and the power grid is active. Minimum reactive power loss. Under the background of large-scale photovoltaic power station, grid-connected inverter and reactive power compensator SVG are used as reactive power source. Firstly, the practical model of large-scale photovoltaic power station is introduced in detail. The influence of large-scale photovoltaic power station on the static stability of power grid voltage is studied. Thirdly, the real-time reactive power difference of photovoltaic power station is adjusted according to the amplitude of parallel voltage QUU. In order to reduce the reactive power transmission and reduce the power loss, the photovoltaic unit and the reactive power compensator are distributed harmoniously in order to maintain the steady operation of the parallel network voltage in order to reduce the reactive power transmission of the collector line in the power station. In the reactive power control, the reactive power compensation device is given priority. When the reactive power compensation device is full, the residual reactive power is allocated to each photovoltaic power generation unit. The reactive power distribution among photovoltaic units is combined with the analysis of voltage / reactive sensitivity. Based on the sensitivity, the reactive power output of photovoltaic power generation unit is determined, which improves the voltage regulation ability of photovoltaic power station. In this paper, the influence of different types of grid-connected photovoltaic power generation system on the static stability of grid voltage is analyzed in detail, and reactive power and voltage control is carried out according to their structural characteristics. It lays a theoretical foundation and decision support for improving the voltage stability and increasing the permeability of photovoltaic system in converging area.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM615;TM761.1

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