Dynamic availability of energy storage in district heating networks for automatic generation control of a CHP plant

To increase power generation flexibility, combined heat and power (CHP) plant needs to improve automatic generation control (AGC) performance. A new approach to use energy storage (ES) in district heating networks (DHN) for AGC is proposed. First, the capacity of ES is analyzed quantitatively. By mechanism analysis of energy flow and conversion between DHN and CHP plant, the capacity and dynamic characteristics of ES in DHN is calculated quantitatively. The calculation result includes the maximum ES capacity and available time, the ES already used by CHP unit, and the remaining available ES and time. Second, basing on the quantitative analysis of ES, a control scheme is designed to make reasonable use of ES. The control scheme uses heat extraction valves as ES control variable and is designed basing on relative gain array method. Finally, a case study of a 330 MW CHP plant is given. The calculation results show that the maximum available time of ES in DHN is 2.85 h. And the simulation results show that the power generation increases by consuming ES in DHN and the AGC response is improved.

Automated summary

A new method of using energy storage in district heating networks for AGC is proposed, which includes quantitative analysis of ES capacity and design of control scheme. The study effectively improves power generation flexibility and AGC performance of CHP plant through reasonable use of ES.