Holomorphic Embedding Power Flow Parallel Calculation Based On Adaptive Power Series Initial Point

With the gradual deepening of the construction of new-type power systems,the large-scale grid connection of renewable energy and the widespread application of power electronic equipment,future power systems will exhibit complex operating characteristics and diverse operating scenarios,posing higher requirements for power flow(PF)calculation.Currently,the Newton Raphson(NR)method has been widely used in power system PF calculation.However,the unreasonable selection of initial values leads to slow or even non convergence of the NR method in PF calculation,and there are still problems such as the singularity of the NR method Jacobi matrix in actual calculation.Holomorphic Embedding Load-Flow Method(HELM),as a new PF solution algorithm,has the advantages of no initial value setting,no Jacobi matrix formation,but when solving PF of large-scale system,the existing HELM requires a higher order of power series for convergence,resulting in a large amount of PF calculation and low calculation efficiency.For this reason,this paper proposes a parallel calculation method of HELM based on adaptive power series initial point,and mainly completes the following work:Firstly,in view of the problem that the traditional HELM reference "flat start" method determines the initial point of voltage power series,which leads to the high order of power series required for solving large-scale system PF,based on the theory of holomorphic embedding method,this paper takes into account the characteristics of different bus types in power system AC PF calculation,a HELM based on adaptive power series initial point(A-HELM)is proposed.According to the system bus admittance matrix and the balance bus voltage,the adaptive adjustment of voltage power series initial point is realized.Based on the PF equation in Cartesian coordinate system,a new model of HELM based on adaptive power series initial point is constructed to realize PF calculation.Secondly,in order to solve the problem that it takes a long time to use the serial calculation method when the traditional HELM is used to solve the approximate solution of the voltage of each bus of the system,based on the proposed A-HELM,this paper further proposes a A-HELM parallel computing method,which takes advantage of multi-core CPU multithreading parallel calculation.In A-HELM calculation,the calculation task of solving the voltage values of each bus of the system in turn based on the Padé approximation analytic continuation method is divided in parallel,and then the voltage Padé approximation calculation task of each bus is evenly distributed to each CPU core,so as to realize the parallel calculation of the proposed A-HELM,reduce the time consumption of the calculation process,and improve the calculation efficiency of HELM calculation of large-scale systems.Finally,the proposed method was analyzed and validated through testing systems of different scales on buses 4-13802.The accuracy of A-HELM is verified by comparing the calculation results of the proposed A-HELM with the existing NR method calculation results in PYPOWER;the convergence of A-HELM is verified by comparing the convergence trend of the proposed A-HELM with traditional HELM;the efficiency of the proposed A-HELM parallel computing method is verified by comparing the computational time of the proposed A-HELM parallel computing method with traditional HELM and A-HELM.The results show that the proposed method can achieve accurate and efficient solution of power system PF,and not only has better PF convergence compared to traditional HELM,but also has higher computational efficiency.