考虑系统峰谷时变区间特性的电压暂降频次评估

故障前电压是影响系统电压暂降频次评估的重要原因之一。现有电压暂降频次随机评估方法,通常假定发生故障前系统母线电压为额定值,而实际故障前电压在电压曲线区间范围内变化,且不同运行方式下随着峰谷变化有不同区间边界。针对故障前电压实际特征,建立故障前电压的数学模型———幅值区间矩阵和时间权重点值矩阵,体现了故障前电压峰谷、时变、区间三大特征。在此模型基础上提出用区间分析的方法评估电压暂降频次的一般步骤。通过对实际区域电网仿真分析,并与故障前电压为额定值和实际截面电压评估结果比较,证明了该模型和算法的正确性和有效性,采用提出方法对电压暂降进行评估,更符合工程实际。

Analysis on Voltage Sag Frequency Considering Peak-valley,Time-varying and Interval Characteristics

Prefanlt voltage is one of the most important factors which will affect the assessment of voltage sag frequency in power system. The current stochastic assessment methods usually assume the prefauh voltage to be the rated value. In practice, however, the prefanlt voltage is varying over a range. The range is always changing during peak and valley period everyday un- der different operating modes. Aiming at the characteristics mentioned above, a mathematical model of the prefanh voltage is established with the interval matrix of vohage magnitude and the time weighted matrix, which reflects the three characteristics, that is, peak -valley, time - varying and interval. For the typical characteristics of the prefault voltage, the common process to assess the voltage sag frequency is proposed in detail on the basis of interval algorithm. The proposed method is performed in the actual power grid. It is proved that it needs only one time of interval iteration process. The simulation results indicate that this method is reasonable and effective.