两区域互联系统交流联络线随机功率波动机制及幅值估计

正常运行时两大区互联系统交流联络线上存在随机功率随机波动的现象,限制了联络线的输电能力。研究了随机功率波动的机制与波动幅值估计。基于系统静态频率特性,推导了两区域交流联络线功率波动的公式,阐明了联络线上的低频功率波动是一种稳态过程,是负荷随机功率波动在全系统中再分配后在联络线上的反映。提出了一种联络线功率波动幅值的概率模糊估计算法。首先通过概率统计的方法来估计系统频率波动幅值的概率分布,再通过模糊数来描述贡献因子的不确定性,最后通过模糊抽样和解模糊来得到联络线功率波动的均值和标准差。通过华北–华中互联系统特高压联络线功率的实测数据验证了所提机制和算法的正确性和有效性。研究有助于掌握两大区互联电力系统的随机功率波动特性,为制定抑制联络线功率波动的措施提供依据。

AC Tie-line Stochastic Power Fluctuation Mechanism and Amplitude Estimation for Two-area Interconnected Power Systems

The stochastic power fluctuation on AC tie-line of two-area interconnected power systems under normal operating conditions reduces the tie-line’s transmission capacity.The mechanism and amplitude estimation of power fluctuation were studied in this paper.The power fluctuation formula was deduced based on the static frequency characteristic of power systems,which indicates that the low-frequency power fluctuation on the AC tie-line is a steady-state process and reflects redistribution of system loads stochastic fluctuation upon the whole system.A probabilistic and fuzzy algorithm to estimate the amplitude of the power fluctuation on the tie-line was proposed.First,the distribution of the system frequency’s fluctuation amplitude is estimated by probabilistic and statistical methods.Then the uncertainty of the contribution factor was described by a fuzzy number.Finally,the expectation and standard deviation of the power fluctuation amplitude was obtained by fuzzy sampling and defuzzification techniques.The correctness and effectiveness of the algorithm was verified by comparing calculation results with measured data of the UHV tie-line of the interconnected power system in north and central China.The conclusions are helpful for operators and engineers to understand characteristics of the stochastic power fluctuation on AC tie-line of two-area interconnected power systems,and provide a theoretic basis for reducing power fluctuation on AC tie-line.