Research On Multi-energy Coordinated Dispatch For Distributed Generation System With RES

Distributed generation systems(DGS)can satisfy power,heat and cool demands of user by means of centralized management and control of multiple distributed generations(DG),and have the advantages of low pollution and high efficiency.There are islanded mode and gird-connected mode for DGS operation.Uncertainty and intermittency are inherent features of renewable energy source(RES),e.g.wind and photovoltaic(PV),causing it is difficult to predict accurately.Therefore,the research on the coordinated dispatch of DGS has an important practical significance for improvement of RES accommodation and economic operation.In this paper,scenario analysis method and robust linear optimization theory are used to deal with the uncertainty of RES.Then from three aspects including virtual power plant(VPP),combined heat and power(CHP)microgird and micro energy network,coordinated dispatches of DGS are studied.Firstly,considering the intraday complementarity and operational characteristic of wind,PV and hydro power,two synergetic dispatch models of a wind/PV/hydro VPP are proposed,the objective of which is to maximize the benefit.One is to decide the power supply level for the given load type considering the interruptible loads under islanded operation mode.The other is to optimize the bid considering the reserves under grid-connected operation mode.To deal with the proposed stochastic programming models with multiple DG,Wasserstein distance index is used to optimally discretize the continuous probability distributions of wind/PV outputs.Furthermore,a set of representative scenarios is generated by using scenario reduction technique.Based on the set of representative scenarios,the stochastic optimization problem is transformed into a deterministic optimization problem.Therefore,the trade-off between the computational complexity and accuracy is achieved.In the numerical analysis,the impacts of the load curve,the wind power price,the price of the interruptible loads and the reserve price on the operation of the VPP are analyzed.The results demonstrate the validity and practicability of the proposed models.Then,the coordinated dispatch of a CHP micorgrid is studied,the purposes of which are to improve the accommodation of RES and reduce the CHP cost.In this paper,the fuzzy character of thermal comfort and the thermal inertia of heating system in CHP microgrid are considered.PMV index which can evaluate the indoor thermal comfort,is used to convert the traditional heat load curve to an interval,by which the elasticity of heat loads are considered at every moment.In addition,an auto-regressive and moving average(ARMA)model is used to characterize the multi period coupling of the multiple temperature parameters in heating system,i.e.thermal inertia,thereby making heat supply adjustable on the time axis.In this paper,the above two characteristics are collectively called two-dimensional controllability of heat loads.The simulation results show that the proposed method can effectively weaken the strong coupling of electric power generation and heat supply,corresponding providing a new idea for the realization of the time shift and optimal matching of heat and power in a microgrid.Finally,considering the thermal response of thermostatically controlled loads(TCLs),the thermal comfort of indoor environments and P2G technology,the models of a micro energy network including cool,heat,electricity and gas are established.Then robust linear optimization theory are used to convert stochastic models into deterministic models.The models established in this paper provide a reference for the further research on the coordinated dispatch of micro energy network.