Study on Dynamic Process Characteristics of CHP Unit With Variable Load Based on Working Point Linearization Modeling

Yuehua Huang,Tianlin Lu,Qing Chen,Jing Ye

doi:10.3389/fenrg.2021.815272

Abstract

In view of the difficulty of applying the refine modeling of combined heat and power (CHP) units to the optimization scenario of integrated energy system, a CHP unit model based on working point linearization modeling is proposed, and its variable load characteristics are analyzed. Firstly, the dynamic coupling relationship of CHP unit is analyzed, and the nonlinear dynamic model of the unit is constructed. Then, under the pure condensation and heating conditions, the linearized Laplace transform model of the working point is established, and the variable load capacity under the independent action of control variables is analyzed to test the availability of the Laplace model. On this basis, the dynamic adaptive particle swarm optimization algorithm is used for multivariable cooperative control to test the open-loop characteristics of the variable load capacity of the unit. At the same time, the control strategy of electrothermal cooperation and safety self-test is designed to adjust the control variables, and test the closed-loop characteristics of the unit’s regulation ability. Finally, a 300-MW steam extraction CHP unit is taken as an example to verify the applicability of the unit model and the effectiveness of the control strategy.

Highlights

Clean, low-carbon, and efficient energy use plays an important role in realizing the strategic goal of “double carbon.” Combined heat and power (CHP) plant is becoming the main energy supply source of the electrothermal integrated energy system (IES) with its superior comprehensive energy supply efficiency (Sun et al, 2021)
There is a difference between the safe main steam pressure involved in the variable load process and the extraction pressure of heating, and the calculation time of one-time optimization is about 5 min, which is a long adjustment time
The dynamic characteristic simulation model of the combined heat and power (CHP) unit based on working point linearization is established, and the open-loop characteristics of the variable load process are analyzed by using the cooperation of improved particle swarm optimization control variables

Summary

Introduction

Low-carbon, and efficient energy use plays an important role in realizing the strategic goal of “double carbon.” Combined heat and power (CHP) plant is becoming the main energy supply source of the electrothermal integrated energy system (IES) with its superior comprehensive energy supply efficiency (Sun et al, 2021). The modeling of the CHP unit variable load capacity is very important for the optimal calculation of power dispatching, frequency regulation, and other scenarios of the IES (Ye et al, 2012; Zhang et al, 2021). Algebraic equations are usually used to describe the feasible region, climbing, and standby capacity of the CHP unit model (Liu et al, 2021) This model is mostly used in the calculation scenario of the unit participating in system long-time scale optimal dispatching (Zhang et al, 2018). The mathematical description considering the internal characteristics of the unit is in the form of differential algebraic equations, which adopts the optimal control method to improve the short-term rapid regulation ability of the unit and participates in the system frequency modulation calculation scene (Wang et al, 2018; Yang et al, 2021). The modeling of the dynamic characteristics of the unit variable load process faces the challenge of meeting the calculation accuracy and solution speed while taking into account the accurate description of unit dynamic characteristics

Methods

Findings

Conclusion