NOVEL CONTROL STRATEGY FOR GRID-CONNECTED PHOTOVOLTAIC ARRAY

In this paper, the configuration of the PV generation system, the dynamic model for PV modules and its power electronic interfacing have been presented. A novel control strategy for the DC-DC converter has been developed in order to extract the maximum amount of power from the PV array. Also, a novel control strategy, which is based on d-q rotating reference frame, has been proposed for the DC-AC converter. The simulation results, based on PSCAD/EMTDC, show that the novel control scheme can transfer the DC energy from PV array, compensate the power factor of AC grid and improve the dynamic behavior of grid-connected PV system

Ferroresonance Suppression in Power Transformers using Chaos Theory

a b s t r a c t The main goal of this paper is the determination of the effect of the metal oxide varistor (MOV) on various ferroresonance modes including fundamental resonance, subharmonic and chaos mode which are generated in electrical power systems. Chaos theory is used for analyzing this effect. Also, the bifurcation, phase plan diagram and time domain simulation are used for this purpose. The proposed power system contains a no-load or lightly loaded power transformer. The magnetization curve of the transformer core is modeled by a single-value two-term polynomial. The core loss is modeled based on the flux of the transformer. The MOV modeled as a nonlinear voltage dependent resistance. The suppression effect of MOV on chaotic ferroresonance in power transformer is studied in this paper. The simulation results confirm that connecting the MOV to the transformer has a considerable suppression effect on ferroresonance phenomena

Integration of CCC-HVDC and VSC-HVDC Systems to Supply an Island Network

Abstract: Acombination of Capacitor Commutated Converter (CCC) HVDC and voltage source converter (VSC) HVDC is proposed to supply an island system without any local generation. The key point of this integration is the flat characteristic of dc voltage of CCC-HVDC, which provides the condition for VSC to connect to CCC dc link via a current regulator. The advantages of proposed combined in feeding system are requiring only one dc line and having better dynamic responses. The structure of the proposed in feeding system as well as its control system is shown in this study. The simulation results are presented to confirm the effectiveness of the proposed system. Two other schemes for in feeding the passive island systems are studied to demonstrate the advantages of the proposed system