Research On Dynamic Optimization Strategy And Online Computing Platform Of AGC For Interconnected Power System

Automatic generation control (AGC) is an important research domain in powersystems because it can accomplish the active frequency control of the power grid,maintain the quality of system frequency, and it can maintain the tie line exchangepower within the reasonable range. The traditional AGC control strategies are mainlyfocused on how to correct area control error (ACE), and its investigation centers on theformulation of the total adjustment power and how to distribute. However, with therapid developing of new energy, popularizing of CPS criterion, marketization of powersystem, the AGC in the modern power system is thus developing to a more complicatedproblem. So the new theory and method must be studied to satisfy the new requirementof the new circumstance.Based on optimization theories and methods, this dissertation is to research andexplore on model, algorithms and the computing platform for the dynamic optimizationstrategy of AGC, which is well-supported by the national natural science foundation“fundamental theory research on the elaborated simulation and probabilistic evaluationof transmission grid’s states for the mid-term and long-term”. Main research contentsand achievements are listed below:An effective dynamic optimization strategy of AGC for the province grid isproposed. With respect to the existing studies, the variation of system frequency isconsidered for the AGC, the constraint of minimum duration time of unit adjustmentand the objective of AGC ancillary service cost are improved. CPS1is optimal and theAGC adjustment ancillary service cost is minimum as objective functions, the CPS1andCPS2indexes, tie line power deviation, the upper and lower limits of unit output, andother constraints of the power system are considered as inequality constraints, to obtainthe optimal plan of base point of AGC unit for the next15min. The results prove thatthe proposed dynamic optimization strategy of AGC for the province grid not only meetthe control performance requirement of the AGC, but also under a power grid with alarge fluctuation by wind power, the CPS index, AGC adjustment ancillary service costare obviously better than other AGC control strategies.A multi-objective immune evolutionary algorithm which is more suitable for thedynamic optimization strategy of AGC to solve is proposed. This model is multi-period,large-scale, with high-level complex constraints and mixed-integer nonlinear programming problem. Based on the complementary constraint relaxation technique,this model is converted as a general nonlinear problem, but it has convergence problemif the Interior Point Method is employed. For solving this problem, objective relativedominant is adopted to tackle with the multi-objectives, the density mechanism isnecessarily adopted into the evolutionary programming algorithm to maintain theindividual’s diversity and guiding the optimal exploring direction in the evolution ofgenerations. The solution of study cases verifies that the multi-objective immuneevolutionary algorithm is able to find the optimal solution of the dynamic optimizationstrategy for province grid. While it has the better optimization performance than theconventional evolutionary algorithm’s, and including excellent convergence ability andfast computation speed.As ultra-high voltage line (UHVL) is recently interconnected, the AGC units ofprovince grid (PD) and regional grid (RD) is difficult to coordinate and the problem ofpower deviation fluctuation of UHVL is increasing serious. Aiming these problems, adynamic optimization strategy of RD and PD AGC is proposed. The dynamicoptimization strategy of RD and PD AGC take AGC adjustment ancillary service cost isminimum as objective, consider power balance of RD and PD, the CPS index of eachPD’s control area, tie line power deviation of interconnected PD and the UHVL of RD,and the adjustment capacity of PD and RD AGC units as constraint. According to thecharacteristics of this model, the immune evolutionary programming algorithm is usedto solve this model. The study cases show that the proposed strategy can meet the AGCcontrol performance requirement and CPS index, and effectively decrease theadjustment times of PD and RD AGC unit and the ancillary service cost, and eventuallythe optimal coordination control for PD and RD AGC unit is implemented.For the purpose of test and application of dynamic optimization strategy of AGCfor the province and the regional grid in the different control center, an onlinecomputing platform of the dynamic optimization strategy of AGC for interconnectedpower system is developed. A function generate method is proposed based on powersystem objects extensible framework which is constructed by XML, the design idea ofsystem architecture based on inter-process communication is adopted, the mechanism ofwatchdog timers is improved. By means of the heterogeneous data integration based onsemantics, memory database management middleware based on connection pool, andother technology, the online computing platform of the dynamic optimization strategyof AGC is developed which can satisfy the requirement of computing time and fault-tolerance, meanwhile, the computing platform has a better performance ofportability, expandability, and maintainability.