含新能源发电的电力系统一次频率响应最低点在线预测

Prediction of nadir point of primary frequency response of power system with new energy generation

在低惯量电力系统中,一次频率响应是一个非常重要的问题。基于频率最低点,可以快速分析频率响应,判断其是否会影响电网的稳定运行,因此提出了一种预测频率最低点的方法。首先,建立了包含基于变频器产生的频率支持的详细频率响应模型,并根据复杂控制回路的共同特点对模型结构进行了简化。简化后的模型可以很容易地得到频率最低点的解析表达式,从而通过参数计算进行频率最低点的预测。在推导的频率最低点表达式中,保留了惯性等频率依赖性很强的系统参数和简化的频率调节参数。为了增强频率最低点预测与实际系统的拟合,这些参数通过在线信息获得,其中系统参数基于在线估计,通过参数辨识得到简化的频率调节参数。实例测试证明了该方法的有效性,且易于实现。

In low-inertia power systems,the primary frequency response is of great interest.Based on the frequency nadir,the frequency response can be quickly analyzed to see whether it will disrupt the stable operation of the grid,so this paper proposes an online prediction method for the frequency nadir.Firstly,a detailed frequency response model containing converter-based generation to provide frequency support is established,and the model structure is simplified according to the common features of the complex control loops.The simplified model can easily achieve the analytical expression of the frequency nadir so that the frequency nadir prediction can be performed by parameter calculation.In the derived frequency nadir expression,the system paramet ers that are strongly frequency-dependent,such as inertia,and the simplified frequency regulation parameters are retained.In order to enhance the fit between the frequency nadir prediction and the actual system,these parameters are obtained through online information,where the system parameters are based on online estimation,and the simplified frequency regulation parameters are obtained through parameter identification.Case tests demonstrate the effectiveness of the proposed method and are easy to implement.