Research On Active/reactive Power Coordinated Optimization Of Comprehensive Energy Saving In Systems

Generation costs can be decreased and primary energy can be saved through active power optimization, while power network losses can be decreased and secondary energy can be saved through reactive power optimization. Through active/reactive power coordinated optimization, comprehensive energy-saving benefits can be optimized.This thesis firstly expounds the mechanism of power system active/reactive power coordinated optimization through the analysis of generator P-Q power limit curve and transportation end power circle curve of a transmission line respectively, what lays a foundation for the establishment and calculation of power system active/reactive coordinated optimization model and algorithm in latter chapters.This thesis takes total generation cost minimization as objective function and establishes an active/reactive power coordinated optimization model in power system based on optimum generation side energy-saving benefits. Through node type conversion, the reactive power outputs of generators are optimized and node voltage violations on different kinds of node are treated. Sensitivity matrix between nodal injective power and branch current is obtained through the establishment of node voltage and branch current functions. Then, branch type is defined and branch flow violations are treated through branch type conversion.Aiming at the irrationality of taking energy consumption or cost index as the unique power dispatching basis under"plant-grid separation"and energy-saving generation dispatching background, this thesis modifies cost index with network loss index, takes total generation cost and active power losses minimization as objective functions and establishes an active/reactive coordinated optimization model in power system based on generation side and grid side optimum comprehensive energy-saving benefits. By means ofλmultiplier, the multi-objective optimization problem is transformed into a single-objective one. Through the definition of optimal comprehensive energy-saving benefits solution on Pareto optimal front set, the optimal value ofλcan be obtained. Then the obtaining methods ofλunder approximate calculation conditions and network loss rate constrained conditions are given respectively.Calculation results on IEEE 30-bus and IEEE 57-bus test systems show the validity of this thesis's work. The research results of this thesis could provide referential evidences for transforming from traditional power generation dispatching model to energy-conservation power generation dispatching model under present power network conditions.