【作者】 李杰；

【导师】 杨龙月；

【作者基本信息】 中国矿业大学 ， 电气工程（专业学位）， 2023， 硕士

【摘要】 为有效解决气候变暖、能源危机等问题,近些年来我国都在大力发展新能源发电技术。随着“双碳”目标的提出,分布式电源(Distributed Generation,DG)在配电网中渗透率逐渐升高,面对DG入网过程中电压质量问题,本文从三相电压不平衡、背景谐波电压、功率波动这三方面对DG入网电压特性进行分析,然后从配电网结构和补偿装置两方面进行电压控制。结构方面是利用节点电压增量将配电网分区,使DG对区域薄弱节点产生一定电压支撑;补偿装置方面是利用有功无功补偿装置进行区域内的功率补偿,缓解越限区域电压问题。主要内容如下:首先,对DG类型和工作原理进行介绍,并对DG接入配电网中的位置、电压等级、容量进行分析。通过对某光伏发电公司进行现场实测,结合国标限值,分析光伏并网各项电压指标变化情况。其次,当配电网处于不同状态时,DG接入对节点电压有很大影响。首先理论分析DG接入位置和数量对系统电压影响,然后考虑配电网处于三相不平衡状态时,节点负序电压变化规律。当计及上级电网背景谐波电压时,将逆变器产生谐波电压与背景谐波电压叠加分析,得出容易超标的谐波次数。最后,考虑DG功率波动较大时,采用MPPT算法进行电压控制。接下来分析DG并网时各节点电压变化规律,利用电压灵敏度对配电网进行电压分区控制。通过改变节点注入功率,构建相应的电压增量矩阵,矩阵中的每一列向量对应配电网中一个节点,对列向量进行聚类从而实现配电网区域划分。区别于其他文献中的单一聚类,本文采用组内链接法、组之间链接法、离差平方和法(Ward法)进行多次聚类。当采用不同聚类算法时,个别节点会划分到不同区域中,对于区域重叠节点,利用其在不同区域中电压增量大小进行具体判定。最后,对于划分区域中出现电压越限时,利用综合电压灵敏度确定补偿装置的安装位置,数值越大的节点越需要进行补偿。然后提出一种区内控制、区间协调的电压控制策略,采用储能装置、静止无功补偿器、电容器、有载调压变压器进行调节。区内控制是一种主动调节方式,根据潮流计算结果调节电压越限区域内补偿装置。区间协调是一种动态优化调节,利用二阶锥优化算法合理控制所有补偿装置出力,获得配电网最优电压分布。最后在IEEE33节点配电网进行算例验证,表明所提策略在控制节点电压上的实用性。更多还原

【Abstract】 In order to effectively solve the problems of climate warming and energy crisis,China has been vigorously developing new energy power generation technology in recent years.With the proposed goal of "double carbon",the permeability of Distributed Generation in the distribution network has gradually increased.Faced with the voltage quality problem in the process of DG entry into the network,this article analyzes the voltage characteristics of DG entry into the network from three aspects: three-phase voltage unbalance,background harmonic voltage and power fluctuation.Then the voltage control is carried out from two aspects of distribution network structure and compensation device.The structure is to use the node voltage increment to partition the distribution network,so that DG can generate a certain voltage support for the weak nodes in the region.In terms of compensation device,the active and reactive power compensation device is used to compensate the power in the region and alleviate the voltage problem in the over-limit region.The main contents are as follows:Firstly,the type and working principle of DG are introduced,and the position,voltage level and capacity of DG connected to the distribution network are analyzed.Through the field measurement of a photovoltaic power generation company and the national standard limit,the change of photovoltaic grid-connected voltage index is analyzed.Secondly,when the distribution network is in different states,DG access has a great influence on the node voltage.Firstly,the influence of the location and quantity of DG access on the system voltage is analyzed theoretically,and then the negative sequence voltage variation rule of nodes is considered when the distribution network is in the three-phase unbalanced state.When considering the background harmonic voltage of the upper power grid,the harmonic voltage generated by the inverter and the background harmonic voltage are superimposed,and the harmonic frequency that is easy to exceed the standard is obtained.Finally,considering the large fluctuation of DG power,MPPT algorithm is used for voltage control.Next,the voltage variation rule of each node is analyzed when DG is connected to the grid,and voltage sensitivity is used to control the voltage area of the distribution network.By changing the injected power of nodes,the corresponding voltage increment matrix is constructed,and each column vector in the matrix corresponds to a node in the distribution network,and the column vector is clustered to realize the regional division of the distribution network.Different from the single clustering in other literatures,this article uses intra-group linking method,inter-group linking method and Ward method for multiple clustering.When different clustering algorithms are used,individual nodes are divided into different regions.For nodes with overlapping regions,the voltage increment in different regions is determined by using them.Finally,when there is a voltage overlimit in the divided area,the installation position of the compensation device is determined by the comprehensive voltage sensitivity.The larger the value of the node,the more need to be compensated.Then,a voltage control strategy of zone control and interval coordination is proposed,which is regulated by energy storage device,static reactive power compensator,capacitor and on-load regulating transformer.The zone control is an active regulation mode,which adjusts the compensation device in the voltage overlimit zone according to the power flow calculation result.Interval coordination is a kind of dynamic optimization regulation,which uses second-order cone optimization algorithm to reasonably control the output of all compensators and obtain the optimal voltage distribution of distribution network.Finally,a numerical example is given in IEEE33 node distribution network to prove the practicability of the proposed strategy in controlling node voltage.更多还原