| As the physical carrier of energy Internet,the integrated energy system includes electric energy,natural gas,thermal energy and other types of energy.It can improve energy efficiency and renewable energy consumption capacity through multi-energy complementary ways,which is the key to solve the increasingly serious energy and environmental problems."Electric-gas coupling" is an important form of integrated energy system.On the one hand,the region-level integrated energy system with electricity and natural gas as the main energy can adopt Combined Cooling Heating and Power(CCHP)to complete Power generation,refrigeration and Heating at the same time to meet the demand of multi-energy load of users.On the other hand,with the gradual maturity of Power to gas(P2G)technology,Power to gas equipment and gas turbine coupled Power and natural gas system realize the two-way flow of energy,which can complete the large-scale,cross-regional transmission of energy.Under the above background,the main research contents of this paper are as follows:(1)Steady-state model and power flow solution method of electric-gas coupling system are studied.Firstly,the steady state models of power system and natural gas system are established.Secondly,the operational characteristics of P2 G and gas turbine are studied,and a simplified linear mathematical model is established.Thirdly,the distributed unit model of CCHP system is established.Finally,the power flow solution methods for the electric-gas coupling system are studied,including the power flow solution method for natural gas system and the hybrid power flow solution method.(2)A regional power-gas coupling system operation optimization method based on energy hub is proposed.Firstly,the theory of energy hub is summarized,and the energy center model based on the theory of energy hub is established considering the real-time energy price and hourly load.Then,the optimal power flow model is established with the minimum system energy purchase cost as the goal and the energy distribution coefficient as the optimization variable,taking into account the equipment capacity,network power flow and other constraints,and the genetic algorithm is applied to solve the problem.Finally,an 8-node distribution network and a 9-node natural gas interconnection system are used as examples to model and solve the problem based on the proposed method,and the economics of the proposed optimization method is verified.(3)A collaborative optimization planning method for cross-region electric-gas coupling system with P2 G is proposed.Firstly,with the goal of minimizing the sum of the annual investment cost and the annual operating cost,a collaborative optimization planning model of power-gas coupling system considering P2 G was established with the optimization objective of the construction status of different types of units,lines and pipelines and the output distribution value of gas turbine and P2 G plant and station.Then,the model solving process based on immune algorithm is studied,and the convergence of the algorithm is analyzed.Finally,based on the proposed method,different scenarios were modeled and calculated for 7-node natural gas and 9-node power systems.The results of immune algorithm calculation showed that reasonable P2 G location planning could reduce the construction cost of natural gas network pipelines,and output adjustment of gas units and P2 G plant stations could reduce the operating cost of the system. |
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