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DC Power Utilizations of Self-Excited Induction Generator with Static VAR Compensator
Tarek Ahmed,Katsumi Nishida,Mutsuo Nakaoka 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-
In this paper, a three-phase self-excited Induction generator(SEIG)-based wind power generation scheme is proposed. This clean power scheme uses a low-cost three-phase diode bridge rectifier connected to the three-phase SEIG to transfer a dc power with the DC voltage regulation. The excitation to the three-phase SEIG is implemented by the static VAR compensator (SVC) composed of the fixed excitation capacitor and the thyristor-controlled reactor. The SVC is used to regulate smoothly the DC load voltage of the three-phase diode bridge rectifier circuit connected to its terminals. This simple method for controlling the reactive power of the SVC is useful for wind turbines installed at high wind speed sites, which are remote or have only weak electrical power networks. The dynamic performance responses and the experimental results of a 5-kW 220-V three-phase SEIG directly connected to a<br/> three-phase diode bridge rectifier at various DC outputs are presented. Moreover, the experimental results of the PI closed-loop feedback voltage regulation scheme-based the SVC prove the practical effectiveness of this simple method for a wind turbine system. This proposed power conditioner with simple control technique, provides a cost-effective method of improving the power quality of wind farms.
Tarek Ahmed,Srawouth Chandhaket,Mutsuo Nakaoka,Song Hwa Jung,Hyun-Woo Lee 전력전자학회 2004 JOURNAL OF POWER ELECTRONICS Vol.4 No.4
In this paper, a two-switch high frequency fly back transformer linked zero voltage soft switching PWM DC-DC power converter implemented for distributed DC- feeding power conditioning supplies is proposed and discussed. This switch mode power converter circuit is mainly based on two main active power semiconductor switches and a main fly back high frequency transformer linked DC-DC converter in which, two passive loss less quasi-resonant snubbers with pulse current regeneration loops for energy recovery to the DC supply voltages composed of a three winding auxiliary high frequency pulse transfomler, auxiliary capacitors and auxiliary diodes for inductive energy recovery discharge blocking due to snubber capacitors are introduced to achieve zero voltage soft switching from light to full load conditions. It is clarified that the passive resonant snubber-assisted soft switching PWM DC-DC power converter has some advantages such as simple circuit configuration, low cost, simple control scheme, high efficiency and lowered noises due to the soft switching commutation. Its operating principle is also described using each mode equivalent circuit. To determine the optimum resonant snubber circuit parameters, some practical design considerations are discussed and evaluated in this paper. Moreover, through experimentation the practical effectiveness of the proposed soft switching PWM DC-DC power converter using IGBTs is evaluated and compared with a hard switching PWM DC-DC power converter.<br/>
Tarek Ahmed,Katsumi Nishida,Mutsuo Nakaoka 전력전자학회 2005 JOURNAL OF POWER ELECTRONICS Vol.5 No.4
This paper describes a simple control structure and power conditioning system for an indirect vector controlled stand-alone induction generator (IG) used to operate under variable speed. The required reactive power for the IG system is supplied by means of a capacitor bank and a voltage-source PWM converter. Using a capacitor bank to transfer the reactive power to the IG under the rated speed and no-load conditions starts the IG operation and reduces the PWM converter size. The vector control structure for the variable speed IG power conditioning system compensates for changes in the electrical three-phase and DC loads while considering the magnetizing curve of the IG. The vector control structure is developed to regulate the DC link voltage of the PWM converter and the IG output voltage. The experimental and simulated performance results of the IG power conditioning system at various speeds and loads are given and show that this proposed scheme can be used efficiently for a variable speed, wind energy conversion system.
Tarek Ahmed,Katsumi Nishida,Shinji Sato,shinichro Nagai,Eiji Hiraki,Mutsuo Nakoaka 전력전자학회 2003 전력전자학술대회 논문집 Vol.2003 No.7(2)
In this paper, a PI controlled feedback closed-loop voltage regulation scheme of the three-phase squirrel cage rotor self-excited induction generator (SEIG) driven by a variable-speed prime mover (YSPM) such as a wmd turbme is designed on the basis of the static V AR compensator (SYC) and discussed in experiment for the promising stand-alone power independent conditioner The simulation and experimental results of the three-phase SEIG with the simple SVC controller for its stabilized voltage regulation prove the practical effectiveness of the additional SVC control loop scheme including the PI controller with fast response characteristics and steady-sate performance improvements<br/>
Tarek Ahmed,Shinichiro Nagai,Mutsuo Nakaoka,Toshihiko Tanaka 전력전자학회 2007 JOURNAL OF POWER ELECTRONICS Vol.7 No.2
In this paper, a novel proposal for a utility-interactive three-phase soft commutation sinewave PWM power conditioner with an auxiliary active resonant DC-link snubber is developed for fuel cell and solar power generation systems. The prototype of this power conditioner consists of a PWM boost chopper cascaded three-phase power conditioner, a single two-switch auxiliary resonant DC-link snubber with two electrolytic capacitors incorporated into one leg of a three-phase V-connection inverter and a three-phase AC power source. The proposed cost-effective utility-interactive power conditioner implements a unique design and control system with a high-frequency soft switching sinewave PWM scheme for all system switches. The operating performance of the 10 kW experimental setup including waveform quality, EMI / RFI noises and actual efficiency characteristics of the proposed power conditioner are demonstrated on the basis of the measured data.
AC and DC Applications of Induction Generator Excited by Static VAR Compensator
Tarek Ahmed,Katsumi Nishda,Mutsuo Nakaoka 전력전자학회 2004 JOURNAL OF POWER ELECTRONICS Vol.4 No.3
This paper presents the steady-state analysis of the three-phase self-excited induction generator (SEIG). The three-phase SEIG with a squirrel cage rotor is driven by a variable-speed prime mover (VSPM) or a constant-speed prime mover (CSPM) such as a wind turbine or a micro gas turbine. Furthermore, a PI closed-loop feedback voltage regulation scheme of the three-phase SEIG driven by a VSPM on the basis of the static VAR compensator (SVC) is designed and evaluated for the stand-alone AC and DC power applications. The simulation and experimental results prove the practical effectiveness of the additional SVC with the PI controller-based feedback loop in terms of its fast responses and high performances
Advanced Control of a PWM Converter with a Variable-Speed Induction Generator
Tarek Ahmed,Katsumi Nishida,Mutsuo Nakaoka,Toshihiko Tanaka 전력전자학회 2007 JOURNAL OF POWER ELECTRONICS Vol.7 No.2
This paper describes simple control structures for a vector controlled stand-alone induction generator (IG) for use under variable speeds. Different control principles, indirect vector control and deadbeat current control, are developed for a voltage source PWM converter and the three-phase variable speed squirrel-cage IG to regulate DC-link and generator voltages with a newly designed phase locked loop circuit. The required reactive power for the variable speed IG is supplied by means of a PWM converter and a capacitor bank to buildup the voltage of the IG without the need for a battery, to reduce the rating of the PWM converter while using only three sensors and to eliminate the harmonics generated by the PWM converter. These proposed schemes can be used efficiently for variable speed wind energy conversion systems. The measurements of the IG systems at various speeds and loads are given and show that these systems are capable of good AC and DC voltage regulation.
Ahmed, Tarek,Nishida, Katsumi,Nakaoka, Mutsuo The Korean Institute of Power Electronics 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.5
In this paper, a 1.5 kW Interior Permanent Magnet Synchronous Generator (IPMSG) with a power conditioner for the grid integration of a variable-speed wind turbine is developed. The power-conditioning system consists of a series-type 12-pulse diode rectifier powered by a phase shifting transformer and then cascaded to a PWM voltage source inverter. The PWM inverter is utilized to supply sinusoidal currents to the utility line by controlling the active and reactive current components in the q-d rotating reference frame. While the q-axis active current of the PWM inverter is regulated to follow an optimized active current reference so as to track the maximum power of the wind turbine. The d-axis reactive current can be adjusted to control the reactive power and voltage. In order to track the maximum power of the wind turbine, the optimal active current reference is determined by using a simple MPPT algorithm which requires only three sensors. Moreover, the phase angle of the utility voltage is detected using a simple electronic circuit consisting of both a zero-crossing voltage detecting circuit and a counter circuit employed with a crystal oscillator. At the generator terminals, a passive filter is designed not only to decrease the harmonic voltages and currents observed at the terminals of the IPMSG but also to improve the generator efficiency. The laboratory results indicate that the losses in the IPMSG can be effectively reduced by setting a passive filter at the generator terminals.
Ahmed, Tarek,Noro, Osamu,Soshin, Koji,Sato, Shinji,Hiraki, Eiji,Nakaoka, Mutsuo The Korean Institute of Electrical Engineers 2003 KIEE International Transactions on Power Engineeri Vol.a3 No.1
In this paper, the comparative steady-state operating performance analysis algorithms of the stand-alone single-phase self-excited induction generator (SEIG) is presented on the basis of the two nodal admittance approaches using the per-unit frequency in addition to a new state variable de-fined by the per-unit slip frequency. The main significant features of the proposed operating circuit analysis with the per-unit slip frequency as a state variable are that the fast effective solution could be achieved with the simple mathematical computation effort. The operating performance results in the simulation of the single-phase SEIG evaluated by using the per-unit slip frequency state variable are compared with those obtained by using the per-unit frequency state variable. The comparative operating performance results provide the close agreements between two steady-state analysis performance algorithms based on the electro-mechanical equivalent circuit of the single-phase SEIG. In addition to these, the single-phase static VAR compensator; SVC composed of the thyristor controlled reactor; TCR in parallel with the fixed excitation capacitor; FC and the thyristor switched capacitor; TSC is ap-plied to regulate the generated terminal voltage of the single-phase SEIG loaded by a variable inductive passive load. The fixed gain PI controller is employed to adjust the equivalent variable excitation capacitor capacitance of the single-phase SVC.