Characterization And Fast Calculation Of Steady-state Feasible Region Of Tie-line Transmission

In China,locations of power resources are uneven and power supply is geographically located in the opposite direction of power demand.To figure out the cross-region and cross-province range of coordinating power resources and achieve the optimal allocation of power resources in a broad range,power transfer capability needs to be accurately calculated.The physical implication of power transfer capability is a feasible region of the tie-line coupling variables(e.g.,tie-line active power,border angles)which meet constraint requirements.By concentrating on the power transfer capability with steady-state constraints in this thesis,the steady-state feasible region of tie-line transmission is studied from the characterization method,the feature extension and calculation accleleration.The major works in this thesis are summarized below.(1)The characterization method of the steady-state feasible region of tie-line transmission based on the multi-parametric programming theory.Considering the economic dispatch model based on the linear DC power flow model,the multi-parametric programming method is employed to calculate the steady-state feasible region tie-line transmission by enumerating different types of active constraints.The steady-state feasible region of tie-line transmission is applied to the hierarchical dispatch in China,validating the effectiveness of the presented method.This validates the accurate calculation of power transfer capability with steady-state constraints,in the form of the steady-state feasible region of tie-line transmission.(2)The externsion method of calculating steady-state feasible regions of tie-line transmission that considers renewable uncertainties,steady-state characteristics associated with reactive power and voltages,and unit commitment.Facing uncertainties caused by renewables,the calculation method for the steady-state feasible region of tie-line transmission that considers renewable uncertainties is presented by constructing chance constraints and joint extreme-scenarios constraints.This achieves the incorporation of renewable uncertainties in the feasible region.Facing the need of the steady-state characteristics associated with reactive power and voltages,the calculation method for the feasible region of tie-line transmission that considers steady-state characteristics(including reactive power and voltage)is presented by deriving the power transfer distribution factor model of the linear power flow model with the steady-state characteristics associated with reactive power and voltages.This achieves the comprehensive consideration of steady-state characteristics.Facing the discrete characteristics caused by the start-up and shut-down,the calculation method for the feasible region of tie-line transmission that considers the on-off characteristic is presented by a bi-level framework of disjunctive statuses.This achieves the characterization of the feasible region with binary variables.(3)The acceleration method of calculating the feasible region of tie-line transmission by the boundary search direction strategy and space dimension reduction strategy.A modified multi-parametric programming algorithm is presented based on the core that is the boundary search direction strategy to avoid the invalid exploration inside the feasible region.This achieves the acceleration of the steady-state feasible region of tie-line transmission.Based on the optimility conditions,the key impact parameters(e.g.,generator capacity,flow limits)of the steady-state feasible region of tie-line transmission are identified,facilitating the effective expansion of the steady-state feasible region of tie-line transmission.Facing the complex computation in the multi-period steady-state feasible region of tie-line transmission,the acceleration calculation is achieved based on the projection and aggregation between the high-dimension space and the lower-dimension space.Based on the equivalent mapping between the optimal solutions in linear programming and vertices of the convex polytope,the accuracy evaluation method and evaluation indicies are presented for the approximation of the steady-state feasible region of tie-line transmission.In a word,the calculation method of the steady-state feasible region of tie-line transmission based on the multi-parametric programming theory is presented in this thesis,together with both the extension methods of multiple characteristics and the acceleration calculation.The presented method figures out the available range of coordinating cross-region and cross-dispatch power resources,and provides the technical support for the optimal allocation of power resources in a broad range.