考虑多台异步电机的电力系统频率响应动态等效模型

Dynamic equivalent model for system frequency response considering multiple induction motors

随着越来越多的可再生能源通过电力电子设备接入电网,电力系统的惯量不断下降,频率波动更加剧烈,同时,在负荷侧存在大量直接并网的异步电机可以提供频率支撑,改善频率响应动态。然而,准确建模如此规模的异步电机需要其详尽参数,并伴随着极高的计算代价。为此,本文提出了一种数据驱动的电力系统频率响应建模方法。该方法首先收集频率响应的历史数据,接下来,将等效惯量和等效阻尼的辨识问题描述为优化问题,优化目标为减少模型与历史数据之间的频率差异,并通过启发式算法高效求解。相较于异步电机的机理模型,所提出的动态等效模型具有不需要异步电机的详尽参数、计算负担小的优点。在修改的IEEE 9节点系统上的仿真验证了所提出方法的有效性,并表明:自身惯量为1.5 s,占负荷侧22%的异步电机负荷为系统提供了9%的等效惯量。

As more and more renewable energy resources are connected to the grid through power converters,the inertia of the power system is decreasing.At the same time,a large number of induction motors on the load side can provide frequency support and improve frequency response dynamics.However,accurate modeling of such a large number of induction motors requires detailed parameters and heavy computational cost.To address the limita⁃tion,a data⁃driven model for system frequency response is proposed.By collecting historical data of system fre⁃quency response,the identification of the equivalent inertia and damping coefficient of the power grid is described as an optimization problem.The objective is to minimize the frequency difference between the model and historical data。A heuristic algorithm is adopted to solve the problem efficiently.Compared with the mechanism model,the proposed dynamic equivalent model is structurally simple and does not require detailed parameters of induction mo⁃tors.Simulations on a modified IEEE 9 bus system verify the effectiveness of the proposed method.The results also show that the induction motor load,which has a self⁃inertia of 1.5 seconds and accounts for 22%of the load side,provides 9%equivalent inertia to the system.