中文摘要：

对电力系统低频减载进行了深入研究，为了避免现有减载方法通过预先设定减载对象和减载顺序而不管该对象减栽时刻的实际负载水平从而导致的减载量不足．提出了基于在线负荷检测的低频减载思路。负载线路的实际负荷量可由自动化系统得到。通过对电力系统频率动态特性的分析，得出了频率变化率与系统功率缺额之间的关系及保证首轮减载量对系统频率恢复的重要意义。提出一种基于在线负荷检测的变电站低频减载方案。该方案以优先满足首轮减载为目标，设定减载线路门槛值，利用变电站自动化系统所获得的线路实时负荷量来判断线路是否列入减载队列．从而保障首轮减栽量。提高频率恢复速度。采用该思路．还可避免切除轻栽线路．提高供电可靠性指标。Matlab仿真结果表明了该方法的有效性。

英文摘要：

The concept of UFLS（Under-Frequency Load Shedding） based on online load detection is proposed. The actual load of the line is acquired from the automation system. The frequency dynamics of power system are analyzed,the relationship between the rate of frequency change and the system power gap is obtained and the importance of UFLS amount in first step on system frequency recovery is emphasized. A substation UFLS scheme based on online load detection is proposed,which takes the UFLS amount in first step as the objective,sets the threshold of load shedding line and arranges the load shedding line queue according to the real-time line loads for ensuring the UFLS amount in first step to improve the speed of frequency recovery. Results of Matlab simulation show its effectiveness.