Assessment Of Real-Time Dispatchable Region For Renewable Generation Considering Reactive Power,Voltage Profiles And Realizability Of Scenarios

Nowadays,with the large scale renewable resources such as wind farms integrated into power systems,it is significant for system operators to reconsider power transmission congestions and real-time power imbalances.In the real-time dispatch,power systems eliminates the uncertainty of the renewable resources by deploying additional ramping capacities and reserve facilities.Some study the feasibility of the re-dispatch given the predispatch strategy.The real-time dispatchable region is defined as the largest range of power injections that the power network can accommodate in a certain dispatch interval for a given dispatch base point.With the increasing number of distributional devices integrated in power systems,it calls for higher accuracy on the calculation of the active and reactive power flows.State of the art research on the dispatchable region adopts a DC power flow model regardless of the voltage profiles and reactive power.To tackle this issue,we focus on the AC power flow model and develop a Column and Constraint Generation algorithm with high solution efficiency.However,the nonlinear constraints are intractable in optimization.In addition,most studies focus on operational constraints in the real-time dispatch,regardless of the realizability of scenarios,where the dispatchable regions are not adjustable concerning real outputs of the renewable resources.In this thesis,we study the influence of the reactive power flows and voltage magnitudes in the dispatchable region.In addition,the historical data is added to the model to consider the realizability of scenarios of the renewable resource generation.We improve the mathematical model of the dispatchable region and introduce a new algorithm in calculation.The contributions of this thesis are summarized as follows:(1)The out-of-limit in reactive power flows and voltage magnitudes will prevent the power systems from accommodating the renewable resources.Most researches on the dispatchable region adopt the DC power flow model regardless of the voltage profiles and reactive power.This thesis proposes an AC power flow based dispatchable region considering the reactive power and voltage profiles constraints simultaneously.The nonlinear constraints in our model are approximated using a linear power flow model together with a polytope approximation technique for the quadratic constraints.We utilize the Column and Constraints Generation(C&CG)to calculate the model.The accuracy of the proposed dispatchable region is verified using two cases.It can be applied to a wide range of scenarios.(2)References studying the dispatchable region disregard the realizability of scenarios of the renewable resource generation.We consider the historical generation of the renewable resources and propose a novel dispatchable region considering realizability of scenarios.We introduce historical data to the new model,which represents the realizability of scenarios.The big M method is utilized to transform the condition restrictions to the linear constraints.We make use of the C&CG algorithm to calculate the dispatchable region within finite iterations.The strategy is to figure out the renewable energy generation scenarios outside the dispatchable region and to generate a hyperplane constraint in each iteration.The proposed model can be solved with accuracy and efficiency if the parameters are selected properly and parallel calculation is applied.Simulation results using the IEEE 30-bus and 118-bus systems illustrate the advantages of the proposed model.