Research On Harmonic State Estimation And Harmonic Source Location In Power System

With the development of power electronic technology and a large number of nonlinear loads are coming into use, harmonic pollution in power system is becoming more and more serious. In order to harness harmonics and reduce harmonic pollution effectively, we must first determine the harmonic distribution or harmonic state in power system. Making use of the limited harmonic measurements, power system harmonic state estimation estimates the harmonic distribution in whole system by the selected state estimator and identifies the allocation and style of harmonic sources, providing a reference for harmonic monitoring, suppression and treatment.The key of harmonic state estimation is to establish its estimator. First, selecting nodal harmonic voltage phasor, nodal injection harmonic current phasor and branch harmonic current phasor of wide area measurement system as measurement quantity, selecting nodal harmonic voltage phasor as state quantity, the mathematical model of linear harmonic state estimation based on phasor measurements is built, which is solved by Generalized inverse matrix method. Taking three typical phasor measurement configurations, underdetermined measurement, basic measurement and determined measurement for example, the influence of PMU configuration on harmonic state estimation result is researched.Second, taking the limitation of phasor measurements into consideration, harmonic active power measurements of supervisory control and data acquisition system are introduced under the condition of unobservable PMU configuration. Selecting harmonic voltage and current phasor of wide area measurement system, nodal injection harmonic active power of supervisory control and data acquisition system as measurement quantity, selecting nodal harmonic voltage phasor as state quantity, the mathematical model of nonlinear harmonic state estimation based on mixed measurements is built, which is solved by both Newton iteration and PSO algorithm, and the influence of power measurements on harmonic state estimation result is researched.Last, nodal injection harmonic active power of all nodes is obtained by using the result of harmonic state estimation. Judging by nodal injection harmonic active power, harmonic source location based on harmonic state estimation is realized. Through constructing the simulation model of IEEE14 bus system, the results of harmonic state estimation and simulation are compared. Then, the theory and algorithm related to this project are validated.