Composite load model of Western Electricity Coordinating Council (WECC) is a newly developed load model that has drawn great interest from the industry. To analyze its dynamic characteristics with both mathematical and engineering rigors, a detailed mathematical model is needed. Although composite load model of WECC is available in commercial software as a module and its detailed block diagrams can be found in several public reports, there is no complete mathematical representation of the full model in literature. This paper addresses a challenging problem of deriving detailed mathematical representation of composite load model of WECC from its block diagrams. In particular, we have derived the mathematical representation of the new DER_A model. The developed mathematical model is verified using both MATLAB and PSS/E to show its effectiveness in representing composite load model of WECC. The derived mathematical representation serves as an important foundation for parameter identification, order reduction and other dynamic analysis.

中文翻译：

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WECC复合载荷模型的数学表示

西方电力协调委员会（WECC）的复合负荷模型是一种新开发的负荷模型，引起了业界的极大兴趣。为了在数学和工程严谨条件下分析其动态特性，需要一个详细的数学模型。尽管WECC的复合载荷模型可以作为模块在商业软件中获得，并且其详细框图可在多个公共报告中找到，但文献中没有完整模型的完整数学表示。本文解决了一个具有挑战性的问题，即从其框图中得出WECC复合载荷模型的详细数学表示。特别是，我们推导了新DER_A模型的数学表示。使用MATLAB和PSS / E对开发的数学模型进行了验证，以证明其在表示WECC的复合载荷模型中的有效性。得出的数学表示法为参数识别，降阶和其他动态分析奠定了重要基础。