低频低压继电器联合减载方法

传统的低频低压减载继电器相互独立,减载时未充分考虑负荷特性以及频率电压的相互影响,在严重扰动下可能出现欠控制或者过控制。提出了一种低频低压继电器联合减载方法,该方法在计及负荷母线频率和电压变化对负荷有功功率影响的基础上,根据实时测得的本地负荷的频率与电压响应信息自动计算低压减载量和低频减载的附加减载量,并将所求得低频减载切负荷量与低压减载切负荷量的较大值作为实际切负荷量输出至低频低压继电器上进行逐轮次就地切负荷。IEEE 39节点系统的仿真结果说明,该方法与传统分散式低频低压减载方法相比,能更好地适应负荷特性和扰动形式的变化,能更有效地保障受扰系统的频率稳定性和电压稳定性。

A combined deloading method based on the underfrequency and undervoltage relay

Conventional undervoltage load shedding (UVLS) and underfrequency load shedding (UFLS), designed separately without considerations of the load characters and mutual influences of the voltage and the frequency, may result in excessive or insufficient load curtailments. This paper proposes a combined deloading method based on the underfrequency and undervoltage relay. This method uses the real-time measured local responses of the frequency and the voltage to calculate the proportion of UVLS and the accessional proportion of UFLS adaptively with considerations of the influences of frequency and voltage dynamics on the load active power. Furthermore, this method adopts the larger proportion between the proportion of UVLS and UFLS as the practical load shedding proportion, and then transmits the practical load shedding proportion to the underfrequency and undervoltage relay, thus triggering local successive load shedding. Simulation results of IEEE 39-bus system have proved that the new method, compared with the conventional one, can adapt better to load characters and disturbance types, thus protecting the power system from frequency and voltage instabilities more effectively.