Objective Power-heat decoupling can help break the constraint of "fixing electricity by heat" in thermal power plants, improve the peak-shaving capabilities of thermal power plants, and promote wind power accommodation.

Method Whereas existing research generally only considered the addition of heat storage tanks and electric boilers in power-heat decoupling retrofit, this paper additionally considered the zero-output retrofit of the low-pressure cylinder. It analyzed the various equipment operating models corresponding to these three retrofit measures, thus establishing a planning model for the power-heat decoupling retrofit of multi-units. This model could jointly optimize the zero-output retrofit decisions for the low-pressure cylinders of coal-fired and gas-steam combined cycle heating units, the power and capacity configuration of heat storage tanks, and the power configuration of electric boilers.

Result Case simulations tested the effectiveness of the proposed model and found that all three power-heat decoupling measures can effectively reduce the proportion of wind curtailment during the heating period, with the maximum reduction reaching 11.64 percentage points.

Conclusion The case analysis also shows that, compared to selecting only one retrofit measure (i.e., only adding heat storage tanks, only adding electric boilers, or only retrofitting the low-pressure cylinder), combining the three retrofit measures can further reduce the system's power generation cost. In the long run, this can improve the overall economics of system investment and operation, with the annualized total cost reduced by 8.98%, 19.15%, and 13.08%, respectively.