Optimal Operation Of Integrated Energy System Considering Virtual Heat Storage

With the rapid development of the economy and society,the demand for energy has been rising violently,which enlarges the gap between energy supply and consumption due to limited reserve of fossil resources and development of renewable energy.Integrated energy system(IES)can upgrade the mode of energy supplying and consuming by breaking the barriers physical interconnection and information interaction between different energy systems,thus research on IES has become a hotpot in the field electricity and energy.For this,the paper studied how to optimize the operation for IES to promote utilizing fossil resources and renewable energy efficiently.And the main research findings obtained are summarized as follows.Firstly,IES containing centralized and distributed energy supply is modeled.The basic energy flow structure of multi-zone integrated energy system with centralized energy supply and distributed energy supply is designed.Basing on distributed heating and electricity network,thermal power unit and wind farm provide energy to IES centrally.And distributed energy supply can be realized by energy equipment such as gas-fired turbine,energy storage,etc.Then,mathematical models of different energy equipments are given basing on their operational characteristics.Besides,by analyzing the principle of central heating,models reflected the characteristics of heating network branch and node are modeled to show the two-dimensional characteristics of heat medium flowing.Secondly,an optimal island operation strategy for regional IES considering virtual heat storage of enclosure buildings in demand is proposed.The heat dissipation of enclosure building is analysed and its virtual heat storage model is deducted by thermal dynamic equilibrium equation.Then,basing on the basic energy flow structure of island IES,an optimal dispatching model to minimize the energy supplying cost is eastablished,which considers constraints consist of energy balance,equipment operation,also enclosure building temperature comfort.To slove the model,an improved interior point method combined with sparse matrix processing technology is designed.Simulation results indicate that economic operation and distributed PV consumption can be achieved by coordinating the outputs of distributed energy equipment including virtual heat storage.Finally,an optimal grid-connected operation strategy for multi-region IES considering virtual heat storage of both enclosure buildings and heating network is proposed.Characteristics and value of virtual heat storage are discussed by analyzing basic principle of central heating and its transmission time-delay for heat medium.Besides,the framework for modelling grid-connected multi-region IES operation optimizing is brought up basing on the hybrid energy supply structure.Then,a hierarchical optimal scheduling model for grid-connected multi-region IES is established,which takes both virtual heat storage of enclosure buildings and it of heating network into consideration.Different energy demand of each region IES is coupling variable between two optimal layers where the lower aims to minimize comprehensive operating cost of regional energy operators and the upper takes integrated energy supply cost of centralized suppliers as target.Also,constraints such as energy balance,network operation,etc,are included.In addition,a bottom-up layer-by-layer solution strategy is adopted to solve the two-layer optimal model.It is verified that the grid-connected optimization scheduling strategy of multi-region IES with integrated bilateral virtual heat storage can be effective in improving the economics and promoting the consumption of renewable clean energy.