Calculation Of Harmonic Power Flow Based On Generalized Tellegen Theorem

The power system is affected by non-linear loads and power electronic devices,resulting in a large number of harmonics in the network.Harmonic injection seriously affects the power quality.It endangers the power network.Harmonic power flow calculation is an important foundation for harmonic analysis.Fast and accurate harmonic power flow calculation method is concerned by the power industry.It has theoretical significance and practical value.It has theoretical significance and practical value.In order to accurately and quickly calculate the harmonic power flow in the power network,the harmonic model and the harmonic admittance matrix model of the typical harmonic generating elements in the power network are first established.Through indepth analysis of the conventional decoupling algorithm,the main factors affecting the calculation speed and accuracy of the conventional decoupling method are given.The improved decoupling method is proposed.Firstly,the decoupling method is improved to form a definite harmonic admittance matrix through sensitivity,it improves the calculation speed of harmonic power flow.Secondly,the harmonic current is linearized.The calculated value of the harmonic current is closer to the actual value.The deviation between the active and reactive power of the node is more accurate.It improves the accuracy of harmonic calculation results.The improved decoupling method and decoupling method are used to calculate the harmonic power flow of the IEEE 22 node system.The accuracy of the former is better than that of the latter,and the calculation speed is also improved.But the improved decoupling method has many iterations and slow calculation speed in harmonic power flow calculation.This requires further optimization.In order to further search for a fast and accurate harmonic flow calculation method,the difference form of the generalized Tellegen theorem and the small perturbation theorem are studied.The harmonic power flow algorithm based on generalized Tellegen theorem is formed on this basis.Firstly,based on the network structure of power system components,the harmonic equivalent model and the harmonic admittance matrix are constructed.Secondly,the generalized Tellegen theorem is used to obtain the simplicity and rapidity of adjoint network equation.The corresponding harmonic network mathematical model and its adjoint network mathematical model are established.The sensitivity matrix is solved to get the harmonic current more accurately.Using the small perturbation theorem and difference form of generalized Tellegen theorem,the concrete steps of harmonic power flow algorithm based on generalized Tellegen theorem are given.The improved decoupling method and the harmonic power flow algorithm based on generalized Tellegen theorem are used to calculate the harmonic power flow of IEEE 33 node system respectively.Based on the generalized Tellegen theorem,the calculation results of harmonic power flow algorithm are consistent with those of the improved decoupling method.The calculation speed is faster than the improved decoupling method.