Osamu Noro

Bio: Osamu Noro is an academic researcher from Kawasaki Heavy Industries. The author has contributed to research in topics: Static VAR compensator & Voltage regulation. The author has an hindex of 12, co-authored 39 publications receiving 462 citations.

Terminal voltage regulation characteristics by static var compensator for a three-phase self-excited induction generator

Abstract: In this paper, the practical impedance approach steady-state analysis in the frequency domain for the three-phase self-excited induction generator (SEIG) with squirrel-cage rotor is presented along with its operating performance evaluations. The three-phase SEIG is driven by a variable-speed prime mover(VSPM) in addition to a constant-speed prime mover (CSPM) such as a wind turbine and a micro gas turbine for clean alternative renewable energy in rural areas. The basic steady-state characteristics of the VSPM are considered in the three-phase SEIG approximate equivalent circuit and the operating performance of the three-phase SEIG coupled with a VSPM and/or a CSPM are evaluated and discussed online under the conditions related to the speed changes of the prime mover and the electrical inductive load power variations with simple computation processing procedures. A three-phase SEIG prototype setup with a VSPM is implemented for small-scale clean renewable and alternative energy utilizations. The experimental performance results give good agreement with those obtained from the simulation results. Furthermore, a proportional-integral (PI) closed-loop feedback voltage regulation of the three-phase SEIG driven by the VSPM on the basis of the static var compensator (SVC) composed of the thyristor phase-controlled reactor in parallel with the thyristor switched capacitor and the fixed-excitation capacitor bank is designed and considered for the wind generation as a renewable power conditioner. The simulation analysis and experimental results obtained from the three-phase SEIG with SVC for its voltage regulation prove the practical effectiveness of the additional SVC with the PI-controller-based feedback loop in steady-state operation in terms of high performance with low cost.

Three-phase self-excited induction generator driven by variable-speed prime mover for clean renewable energy utilizations and its terminal voltage regulation characteristics by static VAr compensator

Abstract: In this paper, the practical impedance approach steady-state analysis in the frequency domain of the three-phase self-excited induction generator (SEIG) with squirrel cage rotor is presented along with its operating performance evaluations. The three-phase SEIG is driven by a variable-speed prime mover (VSPM) such as a wind turbine for the clean alternative renewable energy in rural areas. The basic steady-state characteristics of the VSPM are considered in the three-phase SEIG approximate electro-mechanical equivalent circuit and the operating performances of the three-phase SEIG coupled by a VSPM in the steady-state analysis are evaluated and discussed on line under the conditions related to the speed changes of the prime mover and the electrical inductive load power variations with simple computation processing procedures. A three-phase SEIG prototype setup with a VSPM is implemented for the small-scale clean renewable and alternative energy utilizations. The experimental performance results give good agreements with those ones obtained from the simulation results. Furthermore, a PI controlled feedback closed-loop voltage regulation of the three-phase SEIG driven by the VSPM on the basis of the static VAr compensator (SVC) composed of the thyristor phase controlled reactor (TCR) in parallel with the thyristor switched capacitor (TSC) and the fixed excitation capacitor bank (FC) is designed and considered for the wind generation as a renewable power conditioner. The simulation analysis and experimental results obtained from the three-phase SEIG with SVC for its voltage regulation prove the practical effectiveness of the additional SVC with the PI controller-based feedback loop in the steady-state operations in terms of the fast response and the high performances.

Minimum excitation capacitance requirements for wind turbine coupled stand-alone self-excited induction generator with voltage regulation based on SVC

Abstract: In this paper, the nodal admittance approach steady-state frequency domain analysis of the minimum excitation capacitance required for the squirrel cage rotor type three-phase self-excited induction generator (SEIG) driven by variable-speed prime movers (VSPMs) such as a wind turbine and a micro gas turbine is presented. The steady-state analysis of this power conditioner designed for the renewable energy is based on the principle of equating the input mechanical power of the three-phase SEIG to the output mechanical power of the variable-speed prime mover with using the approximate frequency domain based equivalent circuit of the three-phase SEIG. Furthermore, a feedback closed-loop voltage regulation of the three-phase SEIG as a power conditioner which is driven by a variable-speed prime mover employing the static VAR compensator (SVC) composed of the fixed excitation capacitor bank FC in parallel with the thyristor phase controlled reactor (TCR) and the thyristor switched capacitor (TSC) is designed and considered herein for the wind turbine coupled the power conditioner. To validate the effectiveness of the SVC-based voltage regulator for the terminal voltage of the three-phase SEIG, the inductive load parameter disturbances in a stand-alone power generation are applied and characterized in this paper. In the stand-alone power utilization system, the terminal voltage response and the thyristor triggering angle response of the TCR are plotted graphically. The simulation and experimental results prove the effectiveness and validity of the proposed SVC controlled by the PI controller in terms of fast response and high performances of the three-phase SEIG driven directly by the rural renewable energy utilization like a variable-speed wind turbine.

Virtual Synchronous Generator Control with Double Decoupled Synchronous Reference Frame for Single-Phase Inverter

Abstract: We have proposed the Virtual Synchronous Generator control (VSG control) and have tested it using the demonstration equipment [1]. By using the VSG control, three-phase inverters of current control type are able to run both in grid-connecting operation and in grid-disconnecting operation. Furthermore, in order to control a single-phase inverter like a three-phase inverter using the VSG control, we have applied the technique called “Double Decoupled Synchronous Reference Frame” (DDSRF). In this paper, we will show you the simulation results and experimental results of the single-phase inverter using the VSG control with DDSRF.

Comparison of Dynamic Characteristics Between Virtual Synchronous Generator and Droop Control in Inverter-Based Distributed Generators

Abstract: In recent researches on inverter-based distributed generators, disadvantages of traditional grid-connected current control, such as no grid-forming ability and lack of inertia, have been pointed out. As a result, novel control methods like droop control and virtual synchronous generator (VSG) have been proposed. In both methods, droop characteristics are used to control active and reactive power, and the only difference between them is that VSG has virtual inertia with the emulation of swing equation, whereas droop control has no inertia. In this paper, dynamic characteristics of both control methods are studied, in both stand-alone mode and synchronous-generator-connected mode, to understand the differences caused by swing equation. Small-signal models are built to compare transient responses of frequency during a small loading transition, and state-space models are built to analyze oscillation of output active power. Effects of delays in both controls are also studied, and an inertial droop control method is proposed based on the comparison. The results are verified by simulations and experiments. It is suggested that VSG control and proposed inertial droop control inherits the advantages of droop control, and in addition, provides inertia support for the system.

A Variable Speed Wind Turbine Control Strategy to Meet Wind Farm Grid Code Requirements

Abstract: This paper presents a new operational strategy for a small scale wind farm which is composed of both fixed and variable speed wind turbine generator systems (WTGS). Fixed speed wind generators suffer greatly from meeting the requirements of new wind farm grid code, because they are largely dependent on reactive power. Integration of flexible ac transmission systems (FACTS) devices is a solution to overcome that problem, though it definitely increases the overall cost. Therefore, in this paper, we focuses on a new wind farm topology, where series or parallel connected fixed speed WTGSs are installed with variable speed wind turbine (VSWT) driven permanent magnet synchronous generators (PMSG). VSWT-PMSG uses a fully controlled frequency converter for grid interfacing and it has abilities to control its reactive power as well as to provide maximum power to the grid. Suitable control strategy is developed in this paper for the multilevel frequency converter of VSWT-PMSG. A real grid code defined in the power system is considered to analyze the low voltage ride through (LVRT) characteristic of both fixed and variable speed WTGSs. Moreover, dynamic performance of the system is also evaluated using real wind speed data. Simulation results clearly show that the proposed topology can be a cost effective solution to augment the LVRT requirement as well as to minimize voltage fluctuation of both fixed and variable speed WTGSs.

Enhanced Virtual Synchronous Generator Control for Parallel Inverters in Microgrids

Abstract: Virtual synchronous generator (VSG) control is a promising communication-less control method in a microgrid for its inertia support feature. However, active power oscillation and improper transient active power sharing are observed when basic VSG control is applied. Moreover, the problem of reactive power sharing error, inherited from conventional droop control, should also be addressed to obtain desirable stable state performance. In this paper, an enhanced VSG control is proposed, with which oscillation damping and proper transient active power sharing are achieved by adjusting the virtual stator reactance based on state-space analyses. Furthermore, communication-less accurate reactive power sharing is achieved based on inversed voltage droop control feature ( V–Q droop control) and common ac bus voltage estimation. Simulation and experimental results verify the improvement introduced by the proposed enhanced VSG control strategy.

Nonisolated High Step-up Boost Converter Integrated With Sepic Converter

Abstract: For a nonisolated high step-up converter, the combination of a boost converter with a series output module is investigated in this paper. As a solution to supplement the insufficient step-up ratio and distribute a voltage stress of a classical boost converter, a sepic-integrated boost (SIB) converter, which provides an additional step-up gain with the help of an isolated sepic converter, is proposed. Since the boost converter and the sepic converter share a boost inductor and a switch, its structure is simple. Moreover, the SIB converter needs no current snubber for the diodes, since the transformer leakage inductor alleviates the reverse recovery. The operational principle and characteristics of SIB converter are presented, and verified experimentally with a 200 W, 42 V input, 400 V output prototype converter.

Multi-axis joystick and transducer means therefore

Abstract: The invention relates to improved multi-axis joysticks and associated multi-axis optical displacement measurement means. The displacement measuring means may include one or more light emitters and one or more light detectors, preferably mounted in a planar hexagonal array. The relative position of an adjacent movable reflector assembly can be measured in six degrees of freedom by variations in detected light amplitude. Various ergonomic configurations of six axis joystick embodiments which may be facilitated by the compact design of the transducer means are disclosed. Means for dynamically adjusting coordinate transformations for construction machinery control are also disclosed.