三相不平衡责任量化方法研究

发布时间：2018-12-18 12:48

【摘要】：随着经济的发展,电网中各类负荷的出现,三相不平衡问题日益严重,对三相不平衡源进行责任划分有助于提高用户治理不平衡的主动性,对改善电能质量有重要意义。三相不平衡源引起的公共连接点处母线电压不对称是供电部门关注的主要电能质量问题之一,并以电压(电流)不平衡度作为电能质量考核指标。电网不平衡主要由线路不换位和负载不平衡导致,故为了量化各个负荷单独在电网公共连接点处引起的三相不平衡电压大小,把线路和负载不平衡发射水平进行分离。经仿真发现,公共连接点处的不平衡电压主要由负载引起,故线路产生的不平衡电压可以忽略。负载按线性和非线性可以分为线性负载和非线性负载,论文首先对线性负载的三相不平衡责任量化方法进行研究,给出了IEC法、三相功率流动法、一致和非一致性电流法三种方法的理论框架,通过对比发现可以用一致和非一致性电流法定义负序电流责任,实施奖惩措施;接着论文研究了非线性负载的三相不平衡责任量化方法,论文给出了三相不平衡负序电压责任的定义,其次,由于计算负序电压责任的关键是准确估算系统等效的负序阻抗,论文提出了复数域线性回归的五点细分法,即以五个采样数据为一组进行复数域线性回归,根据误差限值筛选出各个分组中回归的负序阻抗参数,并求取平均值,进而求得系统等效负序阻抗和背景负序电压,仿真验证了此方法的可行性。
[Abstract]:With the development of economy and the emergence of various kinds of loads in the power network, the problem of three-phase imbalance is becoming more and more serious. The division of responsibility for three-phase unbalanced sources is helpful to improve the initiative of users to deal with the imbalance, and it is of great significance to improve the power quality. The voltage asymmetry at common connection points caused by three-phase unbalanced sources is one of the main power quality problems concerned by power supply departments, and the voltage (current) imbalance is taken as the index of power quality assessment. The imbalance of the power network is mainly caused by the line imbalance and the load imbalance. Therefore, in order to quantify the magnitude of the three-phase unbalanced voltage caused by each load alone at the common connection point of the power network, the transmission level of the line and the load imbalance is separated. It is found by simulation that the unbalanced voltage at the common connection point is mainly caused by the load, so the unbalanced voltage generated by the line can be neglected. The load can be divided into linear load and nonlinear load according to linear and nonlinear. Firstly, this paper studies the quantization method of three-phase unbalanced responsibility of linear load, and gives the IEC method and three-phase power flow method. The theoretical framework of the three methods of consistent and inconsistent current method is found to be able to define the responsibility of negative sequence current by consistent and inconsistent current method and to implement reward and punishment measures. Then the paper studies the quantization method of three-phase unbalance responsibility of nonlinear load, and gives the definition of three-phase unbalanced negative sequence voltage responsibility. Secondly, because the key to calculate the responsibility of negative sequence voltage is to accurately estimate the equivalent negative sequence impedance of the system. In this paper, a five-point subdivision method for linear regression in complex domain is proposed, in which five sampling data are taken as a group to carry out linear regression in complex domain. According to the error limit, the negative sequence impedance parameters of each group are selected, and the average value is obtained. The equivalent negative sequence impedance and background negative sequence voltage of the system are obtained, and the feasibility of the method is verified by simulation.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM711

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