Research On Optimal Scheduling Method For Power Generation Load Of Thermal Power Units Under Dynamic Boundary Conditions

With the large-scale access to the power grid of new energy sources such as wind power and photovoltaic power,its strong randomness and volatility have a great impact on the security and stability operation of the power grid.The problem of power grid peak and frequency modulation has become prominent.However,China’s power supply structure determines that thermal power units are still the main force of power grid peak and frequency modulation.Improving the flexibility of thermal power units is a realistic choice to solve the problem of peak and frequency modulation in China’s power grid.The two aspects of improving the flexibility of thermal power units include expanding the power generation load regulation range of thermal power units and increasing the power generation load regulation rate of thermal power units.At this stage,reducing the lower limit of power generation load of thermal power units is a key issue to be solved.In the process of flexibility transformation of thermal power units,the boundary conditions and time-varying of unit operation are more obvious,which has become an important reference for the formulation of power grid dispatching plans.In the winter heating period,a large number of heating units in the northern part of China work in the “heat-fixing” mode.In order to ensure a certain thermal output,the operating load of the units is generally high,and the peaking capability that can be provided by the units is limited.At the same time,the winter heating period is also the high load period of wind power.Therefore,improving the peaking and frequency modulation capability of the heating unit is also the key to improving the wind power capacity of the power generation side.Based on the analysis of the operating boundary characteristics of thermal power units and the mechanism of heat storage widening load regulation range of heat supply units,the method of optimizing the power generation of thermal power units on different time scales is studied:(1)The optimal dispatching model under traditional scenarios is constructed and analyzed through practical example.Furthermore,the load adjustable flexibility of pure condensation units on short time scale is combined with that load scheduling flexibility of thermoelectric units with thermal storage on daily time scale.A day-ahead planning model of thermal power units with thermal storage device considering wind power integration is established.(2)The dynamic boundary characteristics of thermal power units in the new environment are analyzed.The boundary conditions of the units operation are divided into the various stages of the grid dispatching,and the economics and rapidity of the units load adjustment are considered in the real-time planning model.By establishing a multi-time scale thermal power units load optimization scheduling model,the units’ planned power generation load is modified step by step to achieve the requirements of refined scheduling.The research shows that the load dispatching model that can give full play to the adjustable flexibility of the pure condensing units and the scheduling flexibility of the heat supply units with heat storage can further improve the wind power consumption level in the previous plan;The multi-time scale load optimization scheduling method considering the dynamic boundary conditions of thermal power units can better ensure the rationality of the power grid dispatching plan of thermal power units under different operating conditions.