Probabilistic Optimization Method Of Pilot-bus Selection And Network Partitioning Algorithm

The pilot-bus selection and the network partitioning for reactive power control are closely related and cooperating together,which concerns the effect of secondary voltage control and makes it the core function of the AVC system of the transmission grid.The centralized access of large-scale wind power and the construction and promotion of ac-dc system have brought profound influence on the selection of pilot-bus and the network partitioning for reactive power control.On the one hand,in the case of high wind power permeability and severe load fluctuation,the reactive power is frequently partitioned,which leads to the difficulty in the implementation of graded voltage control in practical projects.On the other hand,with the HVDC system being put into operation one after another,China has gradually formed a transmission network featured by ac/dc interconnection,which puts forward new requirements for the selection of pilot-bus and network partitioning for reactive power control.Therefore,a research on this has been carried out in this paper,the main content is as follows:(1)In order to accurately describe the source and load power state and characteristics of pilot-bus and network partitioning,a random source and load power scene simulation method considering the maximum reactive power demand in partition was proposed.Randomness and relevance of load and wind power is showed by the distribution function and correlation coefficient of source and load power.A scene compression method considering the maximum zonal reactive power demand is established.Through this method,typical scenes and corresponding explanation can be obtained,and the simulation of random source and load power.Simulation comparison is also made to verify its validity.The proposed method not only considers the randomness and relevance of wind power and load,but also takes the clustering scene and regional scene into consideration,which overcomes the extreme scene reservation problem of the conventional scene compression method,and it worth promoting.(2)In order to guarantee the efficient and reliable maintenance of the AVC system operation,this paper proposes a probability optimization method of the AC system master node pilot-bus selection and reactive partition.In this paper,based on the harmonized optimization thought of selection of the Pilot-Bus and network partitioning,the probability optimization model of selection of the pilot-bus and reactive partition network partitioning is built considering the random variation of the source and charge power relationship,and also considering the partition balance requirement of reactive power when the source and charge power relation are randomly changed.The randomness and relationship of the load to the air power is represented by the normal distribution,Weibull distribution and correlation coefficient,respectively,and the satisfaction degree of the partition reactive balance is represented by the chance constraint.The source-charge power scenario is simulated by a random source power scenario simulation method that considers the maximum reactive power requirement of the partition,and then the optimization model is solved using an immune genetic algorithm based on the relative superiority of the target.The effectiveness of the proposed method is verified based on IEEE39 node system.The resulting scheme is capable of accommodating various variations in the source charge power over a longer period of time and satisfies the requirement that the network partitioning scheme is held constant over a longer period of time for engineering applications,(3)In order to consider the impact of high voltage DC system access on pilot-bus selection and Reactive Partitioning methods,a probability optimization method is proposed for AC and DC System pilot-bus selection and Reactive Partitioning methods.Based on the controllable observability of the pilot-bus,this method further takes into account the voltage control requirements of the partitioned power supply to its internal commutator station nodes,establishes an optimization objective considering the controllability of the AC and DC coupling points,and loads the commuter station node power equivalently,and makes simulation of a typical scenario of the power of the source-load-Bus-commuter station node take into account the partition balancing requirements of the reactive power of the source-load-commuter-station node.The effectiveness of the proposed method was verified by solving the optimized model by a target relatively dominant immune genetic algorithm and performing a simulation test.This method can not only ensure that the partitioned power supply has strong voltage control capability for its internal commutator node,can meet the requirements of the DC/AC system for the high voltage control of the commutator node,but also can fully meet the reactive power balance requirements under power scenarios of each source-load-commutator node,which can help the DC/AC system to work normally and prevent accident.