An equivalent thermal model for dynamic analysis of integrated electricity and heat systems for renewable energy accommodation

Abstract

The rapid development of electric heating and combined heat and power generation for improving the level of renewable energy accommodation has necessitated integrated analysis of the electric power system and district heating networks. However, the thermal dynamic model is governed by partial differential equations related to time and space variables. Its complicated features make it hard to perform an efficient integrated analysis with renewable fluctuation. To address this issue, this paper propose an equivalent model for an accurate and concise integrated dynamic analysis. First, an analytical formulation is derived based on Laplace transform to explicitly describe the relation between the port temperature. The transform avoids the discretization in time domain, which accurately captures the thermal dynamics. On this basis, a space discretization strategy is introduced to further keep track of the dynamics. Meanwhile, the multiple cascaded space pipeline segments are aggregated to form an equivalent model for a concise analysis. Furthermore, to reduce the model complexity and computational burden of the high-order Laplacian “s” in the equivalent process, a reduction strategy is developed by preserving the low-frequency thermal dynamic feature. Then, the analytical expression of state fluctuation can be conveniently derived to analyse the embedded impact and interaction between EPS and DHN. Finally, case studies are conducted to prove the effectiveness of proposed model.