Research UPQC Improved Detection Methods

Power is the main energy of modern society, which is widely used in allwalks of life. And the national economy relates to the quality of power directly.With the increment of non-linear components of load, the grid structure is moreand more complex, and the situation that various problem of power qualityoccur simultaneously will be more common. The United Power QualityConditioner(UPQC),which possesses the ability of comprehensive compensation,becomes research focus gradually.This paper described the harms of power quality problems, reasons,solutions, and the necessity of research Unified Power Quality Conditioner. Also,analysis the mathematical modeling of the series parallel compensation unit andDC energy storage unit were set up and the power flow.The compensation effects for the two influence factor test are comparedwith those of the control links detailed analysis and verification, the maincontents are as follows:(1)Detection part: Aiming at the condition of the asymmetrical three-phase gridvoltage, on the basis of synchronous coordinate transformation method isintroduced into the software phase-locked loop (SPLL), which improved theaccuracy of the synchronous signal. And simplify the circuit of voltage detectionlink, thus reducing the amount of calculation, quickness and the effectivenessachieved(2)Control links: for the problem of interphase interference in three-phasethree-wire system, constant frequency hysteresis tracking control method basedon space voltage vector is proposed, meanwhile, the problem that switchfrequency is unstable and the controlled variable is uncontrollable duringtransposition of load is solved.(3)According to the model of detection and control part of the simulationstructures, establish the general simulation model of the UPQC.The comparisonwith the traditional method, this article uses the method of UPQC that combinedthe SVPWM constant frequency hysteresis control with the detection method of SPLL and dq, which is more comprehensive to solve the problem of powerquality.