Papers by Keyword: Distributed Generation System

Abstract: Distributed generation system (DGs) is considered to be an advanced configuration of distributed generation through the effective organization of renewable energy power sources, loads and energy storage devices, which can operate either isolation or connected with grid. This paper studied the control of DGs which is constructed with DFIG (Double Fed Induction Generator) based Wind Farm, PV (Photovoltaic) generation farm and Storage Batteries. The paper studied the simulation model of the DGs and the control strategy.

Abstract: In order to adapt the grid test study of distributed generation system, a multifunctional variable voltage and variable frequency power supply is proposed. The power supply could work in four quadrant operations, so that energy generated by distributed systems could flow into grid. The fundamental voltage and harmonic voltage are controlled respectively: multiple feedback loop control scheme is applied in fundamental mode and effective value feedback control scheme is applied in harmonic mode. The DSP and FPGA platform are used for implementing the system control and the experimental results show that the performance of the simulator is good and has high stability.

Abstract: If a doubly fed induction generator (DFIG) were to penetrate into a distributed generation system successfully, it should be able to adapt to autonomous and unbalanced conditions. To dealing with this situation, an indirect stator flux orientation (ISFO) control strategy with the droop method is introduced to cope with the positive sequence components of DFIG and provide the system with a solid voltage and frequency support. Meanwhile, a negative sequence droop is also proposed for DFIG so as to achieve a reasonable sharing of unbalanced loads and ensure the power supply quality at the point of common coupling (PCC). Finally, simulation results are provided to demonstrate the correctness of the suggested control strategy under autonomous and unbalanced conditions when DFIG is connected in parallel with a converter.

Abstract: In this paper the connotation and the different definition of micro-grid were expounded, the basic structure of micro-grid was described, and the key technologies of smart grid were expatiated on. Finally, the directions for future research in our country of micro-grid are elucidated.

Abstract: The paper proposes a quasi resonant direct power control algorithm for three-phase grid-connected inverters without grid voltage sensors in distributed generation systems. According to the active and reactive power references, grid virtual flux and the inverter output current references are calculated. In order to accurately and fast track the output current references, the quasi proportional resonant (QPR) controller is used. The theoretical principle of this method is discussed. The steady-state and dynamic experimental results of quasi resonant direct power control that can illustrate the operation and performance of the presented control strategy are displayed. It is shown that the control system exhibits several advantages, such as constant switching frequency, sinusoidal grid currents and good dynamic response. Experimental results are provided to demonstrate the effectiveness of the proposed control strategy.

Abstract: This paper investigates harmonics in power systems especially harmonics produced by synchronous generators as well as those by distributed generation systems, particularly these days when private generating systems are on the increase in Nigeria. For the work done so far, we found that some generators have near square waves, and these are characterized by their odd harmonics. An investigation of the harmonic emf waves conducted shows that these generators produces harmonic alternating mmf’s and fluxes. All harmonic fluxes produce emfs which are undesirable. The effect of these harmonics results in additional losses, vibration and noise, interferences, and very often stall motors. However the useful torque of a machine is usually produced by the fundamental flux wave which is a pure sine wave. The work is on-going. The waveforms are being analyzed so as to determine the full spectrum of the harmonics present in each case and subsequently investigate their effects in telecommunication systems including the present day GSM.