Two-Stage Real-Time Frequency Regulation Strategy of Combined Heat and Power Units with Energy Storage

In view of the frequency regulation (FR) policy in Northeast China, a two-stage real-time rolling optimization model for power plants participating in FR ancillary services is established. The optimization object of the first stage is to maximize the overall profitability of the power plant and to obtain FR performance sub-indicators (K1, K2, K3) and the electric power curve of combined heat and power (CHP) units with energy storage. The second stage of the model performs load distribution with the objective of minimizing operating cost, subject to the constraint of electric and heat power balance for CHP units and energy storage. Meanwhile, rolling optimization combined with dynamic correction is used to ensure the accuracy of the two-stage FR optimization model by updating the operating status of the CHP units and energy storage and reducing the prediction errors of the FR commands. The above models have been validated by actual case studies of a CHP plant in Northeast China. They can ensure the economic and sustainable operation of CHP units and energy storage, enabling the CHP plant to benefit in the FR ancillary services market. The models offer a useful reference for CHP enterprises in terms of FR.