M. Saitou

Bio: M. Saitou is an academic researcher from Nagoya Institute of Technology. The author has contributed to research in topics: Harmonics & Capacitor. The author has an hindex of 1, co-authored 2 publications receiving 136 citations.

A control strategy of single-phase active filter using a novel d-q transformation

Abstract: In this paper, a control strategy of the single-phase active filter using a novel d-q transformation is proposed This d-q transformation is implemented by using Hilbert transform, by which the instantaneous single-phase voltage and current are converted into complex vectors (analytic signals) on the instantaneous basis Since the fundamental components of voltages and currents are converted into DC components on the d-q coordinate both in the steady and transient states, the harmonics of voltages and currents can be obtained precisely through the low-pass filer installed on the d-q coordinate This results in the economical active filter with a small capacitor suppressing the DC bus voltage fluctuation because the fundamental power can be fully removed from the active filter input

Modeling and harmonic suppression for distribution systems

Abstract: Expansion of voltage distortions along with power distribution systems, which is referred to as the harmonic propagation, is pointed out. This is caused by the LC resonances between the distribution line inductances and the power capacitors. This paper presents a modeling and harmonic suppression procedure for power distribution systems. In our proposal, a power distribution system is analyzed using the modal analysis and is represented by a reduced order model. For the harmonic suppression, a series active filter is used and its controller is designed based on the reduced order model. Some significant characteristics are verified by using a single-phase simulated full order model.

A New Single-Phase PLL Structure Based on Second Order Generalized Integrator

Abstract: Phase, amplitude and frequency of the utility voltage are critical information for the operation of the grid-connected inverter systems. In such applications, an accurate and fast detection of the phase angle, amplotude and frequency of the utility voltage is essential to assure the correct generation of the reference signals and to cope with the new upcoming standards. This paper presents a new phase-locked-loop (PLL) method for single-phase systems. The novelty consists in generating the orthogonal voltage system using a structure based on second order generalized integrator (SOGI). The proposed structure has the following advantages: — it has a simple implementation; — the generated orthogonal system is filtered without delay by the same structure due to its resonance at the fundamental frequency, — the proposed structure is not affected by the frequency changes. The solutions for the discrete implementation of the new proposed structure are also presented. Experimental results validate the effectiveness of the proposed method.

New positive-sequence voltage detector for grid synchronization of power converters under faulty grid conditions

Abstract: This paper deals with a fundamental aspect in the control of grid-connected power converters, i.e., the detection of the positive-sequence component at fundamental frequency of the utility voltage under unbalanced and distorted conditions. Accurate and fast detection of this voltage component under grid faults is essential to keep the control over the power exchange with the grid avoiding to trip the converter protections and allowing the ride-through of the transient fault. In this paper, the systematic use of well known techniques conducts to a new positive-sequence voltage detection system which exhibits a fast, precise, and frequency-adaptive response under faulty grid conditions. Three fundamental functional blocks make up the proposed detector, these are: i) the quadrature-signals generator (QSG), ii) the positive-sequence calculator (PSC), and iii) the phase-locked loop (PLL). A key innovation of the proposed system is the use of a dual second order generalized integrator (DSOGI) to implement the QSG. For this reason, the proposed positive-sequence detector is called DSOGI-PLL. A detailed study of the DSOGI-PLL and verification by simulation are performed in this paper. From the obtained results, it can be concluded that the DSOGI-PLL is a very suitable technique for characterizing the positive-sequence voltage under grid faults.

Performance evaluation of PLL algorithms for single-phase grid-connected systems

Abstract: Phase angle, frequency and amplitude of the utility voltage vector are basic information for an increasing number of grid-connected power conditioning equipments, such as PWM rectifiers, uninterruptible power systems (UPS), voltage sag compensators and the emerging distributed generation systems. For these applications, accurate tracking of the utility voltage vector is essential to ensure correct operation of the control system. This paper presents a comparative study of synchronous reference frame PLL algorithms for single-phase systems. Simulation and experimental results, including operation of the PLL structures under distorted utility conditions are presented, to allow a performance evaluation of the PLL algorithms.

Performance evaluation of PLL algorithms for single-phase grid-connected systems

Abstract: Phase angle, frequency and amplitude of the utility voltage vector are basic information for an increasing number of grid-connected power conditioning equipments, such as PWM rectifiers, uninterruptible power systems (UPS), voltage sag compensators and the emerging distributed generation systems. For these applications, accurate tracking of the utility voltage vector is essential to ensure correct operation of the control system. This paper presents a comparative study of synchronous reference frame PLL algorithms for single-phase systems. Simulation and experimental results, including operation of the PLL structures under distorted utility conditions are presented, to allow a performance evaluation of the PLL algorithms.

Enhanced power quality control strategy for single-phase inverters in distributed generation systems

Abstract: Power electronic converters are commonly used for interfacing distributed generation systems to the electrical power network. This paper deals with a single-phase inverter for distributed generation systems requiring power quality features, such as harmonic and reactive power compensation for grid-connected operation. The idea is to integrate the DG unit functions with shunt active power filter capabilities. With the proposed approach, the inverter controls the active power flow from the renewable energy source to the grid and also performs the non-linear load current harmonic compensation keeping the grid current almost sinusoidal. The control scheme employs a current reference generator based on Sinusoidal Signal Integrator (SSI) and Instantaneous Reactive Power (IRP) theory together with a repetitive current controller. Experimental results obtained on a 4 kVA inverter prototype demonstrate the feasibility of the proposed solution.