Time-Domain Decoupling and Analytical Evaluation of Boiler Thermal Storage for Adaptive AGC Dispatch

Under escalating renewable energy penetration, conventional automatic generation control (AGC) dispatch based on static rated capacity fails to accommodate the intrinsic thermal dynamics of coal-fired units, frequently causing main steam pressure excursions and secondary frequency drops. To overcome this critical bottleneck, this paper presents an adaptive AGC dispatch framework driven by time-domain decoupling and real-time analytical evaluation of boiler thermal storage. First, by aggregating lumped heat storage and equivalencing fuel combustion delays, an analytically tractable second-order model characterizing the boiler-fuel system is formulated. Utilizing a full-response time-domain decoupling method, the dynamic trajectory of throttle pressure is decoupled into zero-input and zero-state responses, enabling an explicit analytical calculation of the maximum allowable power disturbance the unit can withstand without breaching pressure constraints. This transient margin serves as a physical metric to dynamically update the AGC allocation factors across generating units in real time, avoiding online iterative computational burdens. MATLAB/Simulink simulations verify that while effectively utilizing the thermal storage potential of generating units, the proposed strategy maintains main steam pressure within allowable operational boundaries, effectively mitigating secondary frequency drops under the tested disturbances and enhancing the frequency stability of the power grid.