Optimal Coordination Of Source-Network-Load-Storage For Day-ahead Operation Of Active Distribution Network

Distributed generation(DG)is becoming important due to their clean and re-newable characteristics with the situation that conventional fossil-energy-based gen-eration has been causing serious pollution and gradually depleted.However,with the DG access to the power grid,many challenges appear with the opportunities,e.g.the asymmetry between supply and demand causes that the grid cannot accept the DG output,and the sudden off-grid of DG causes safety problems.Active distribution network(ADN)takes the active control of DG,which can give full play to the regu-latory role of various controllable resources by the coordination of source network load storage(SNLS).It can make the system operate economically,safely and reliably.The penetration rate of DG can be also improved.ADN plays an important role in the future power grid.Meanwhile,the coordination of various controllable resources is full of theoretical significance and practical significance.According to the definition of ADN,the controllable resources in ADN can be mainly divided into four parts,i.e.DG,grid structure,controllable load and battery energy system(BES),The economic and security level of ADN can be well improved by adjusting network topology.Besides,controllable load and BES are able to im-prove the economic level and assist renewable DG integration in day-ahead dispatch,which are important as flexible resource in ADN.A single controllable resource can be optimized to achieve a certain effect.Nevertheless,coordinated optimization of multiple controllable resources can often achieve better results in terms of economy,safety,reliability,and so on.Firstly,take the coordination of source and network as an example.For the tra-ditional nonlinear model,it is difficult to converge and it is easy to fall into a local optimum.In consequence the equivalent linear model of load and generations is es-tablished,respectively.As far as the strong non-linear problems for calculating the number of actions in distribution network reconfiguration(DNR),a linear calculation is proposed based on the characteristics of network structure,which transforms the absolute problem to a linear problem.On the basis of what has been mentioned above,a convex optimization model is proposed to minimize the scaled cost.The simulation is carried out in IEEE 33-bus system with the MATLAB and GAMS software.The correctness of the model and effectiveness of SNLS are demonstrated by the simulation results.And it is necessary to consider the cost of DNR.Based on the coordination of source and network,a prolongable linear switching operations calculation method is proposed to improve the narrow applicable range of the above linear reconstruction calculation method.Take into account the linear equivalent model of TOU-based responsive load(RL)and BES,component charac-teristics constraints and network security constraints,the mixed integer linear pro-gramming(MILP)model of SNLS in ADN is proposed to minimize the total daily operation costs.Several combinations of controllable resources are put forward.The simulation results on a modified 69-bus system show that the coordination of SNLS has a good optimization effect.