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This paper describes a phasor-measurement-unit (PMU) calibration method and presents the measurement results of the characteristics of an inductive voltage divider (IVD) and a current shunt. The frequency characteristics of an IVD and a current shunt were evaluated up to 10 kHz in terms of PMUs. The in-phase components of the IVD were less than 0.39 ppm, whereas its quadrature components reached 0...
Virtual Synchronous Generator (VSG) is an inverter control structure that supports power system stability by imitating a synchronous machine. Because of the limitation in inverter power and current, their operation under disturbances should be evaluated and enhanced. In this paper, the VSG unit response to different types of faults at grid side is assessed. Besides, a theoretical analysis that traces...
This research developed an eccentric disk and novel circular Halbach array to harvest wave energy from the rolling motion of a ship. The designed eccentric disk revolves in a motion that mimics a hula-hoop at higher angular speeds than eccentric disks oscillate normally having. The produced kinetic energy was converted into electrical energy through electromagnetic induction. To enhance electromagnetic...
In this paper, we would like to review and introduce technologies which mitigate problems in an electric power grid caused by installation of renewable energy sources (RES). We classified these technologies into three types of technologies in an analogy of “medical therapy” categorization, which are “causal therapy”, “symptomatic therapy”, and “infection prevention”. As for the causal therapies, active-power-based...
It is an ideal to perform a combined test of an inverter and a motor for a smooth start-up at the site. There is a method to carry out a full load test without driving a machine. It is called “Back-to-back test”. It is possible to obtain 25MW output of testing facility in our company. In this paper, it is introduced the performance evaluation of the test results such as, torque ripple analysis of...
Multilevel converters are widely recognized as a suitable solution for directly interfacing different types of power sources and energy storage systems to the medium voltage grids, due to their ability in high-voltage and high-power applications. The DC-voltage regulation of a five-level neutral-point clamped (NPC) in closed loop is presented. It consists to regulate the average value of the DC-voltage...
A novel structure for power maximization of the PV (photovoltaic) system under partially condition is presented. By using CSI (Current Source Inverter) instead of VSI (Voltage Source Inverter), the structure of PV system becomes extremely both more simple and reliable than conventional one. It means that MICs (Module Integrated Converters) can be consisted of buck-only converters and electrolytic...
This paper introduces a new method of generator brake torque control during Fault Ride Through (FRT) drive for a multi level matrix converter of wind power system. It may be exist that a generator speed become over speed during FRT drive. In this case, a generator has to be fixed brake torque. In the past, generator brake torque control during FRT drive for a matrix converter is impossible. However,...
H-bridge cascaded static synchronous compensator (STATCOM) is often used to compensate the harmonic and reactive current derived from non-linear load. However, with the special topology structure, the voltage balancing of DC capacitors of H-bridge cascaded STATCOM is a key problem. Many papers adjust active voltage to solve this problem with the conventional PI controller which needs to regulate the...
This extended abstract discusses the design of a power and control architecture for wireless communication networks that enables an increased use of renewable energy sources than in the conventional present approach. In the proposed approach a group of cell sites forms a dc microgrid in which their power consumption is coordinated with the power generated from renewable sources in order to manage...
This paper proposes a novel method of suppressing inrush currents of squirrel-cage induction machines using matrix converter in wind power generation systems. In the proposed method, the series-connected side of the matrix converter behaves as a resistor for the induction machine current. Digital computer simulation is implemented to confirm the validity and practicability of the proposed method using...
In DC microgrids, the operation of the constant power load (CPL) and its associated input filter is very likely poorly damped if no damping method is applied. Active damping methods can significantly improve the power efficiency comparing with the passive damping methods. This paper proposes an active damping method which builds a virtual resistance in the source side converter, and it can effectively...
AC-Choppers using instantaneous voltage control technique to solve voltage sag problems are proposed in this paper. The developed AC-chopper for series voltage sag compensation is applied for three phase four wire system; therefore, three single phase ac chopper circuits and three series transformers are utilized. By using AC-chopper, there are no required for a dc bus; thereupon, the size of proposed...
In order to save sensors for the grid-connected inverter (GCI) with LCL-filter in the full-scale wind power converter, a grid-side voltage-sensorless solution scheme is presented in this paper. A frequency-adaptive SOGI (FA-SOGI) is introduced to realize the virtual flux (VF) estimation. A grid-side voltage observer is thus designed to acquire the phase angle and amplitude, which can realize voltage...
This paper presents a front-to-front (FTF) system based on modular multilevel cascade converters (MMCC). It is called an FTF system because the ac sides of the MMCCs are connected together making a front-to-front configuration via a medium-frequency transformer for voltage matching and galvanic isolation. The system configuration is applicable to dc power collections. Moreover, it is suitable as a...
In Japan, Feed in Tariff has started since July in 2012. Moreover only solar power is not attractive energy, a wind turbine generator is attractive energy from the point of view to reduce double carbon oxide emission. However, to connect the wind turbine generator system to the grid, the independent power producer (IPP) must compensate the power disturbance caused of the wind turbine. Thus, a power...
A promising topology to interconnect the wind power plants is proposed. Advantages of series-connected system over ordinary parallel system are first discussed, and control strategies for the series-connected system are studied to realize an optimum use of the wind energy. The dynamic performances of the series-connected system are investigated through simulation and experiments. An effective method...
This paper proposes the new simple current measurement method. It utilizes the voltage measurement of the MOS-FET switching device at the dc-dc converter to measure the current instead of conventional measuring methods, such as the DC-CT or the shunt resistance. The precise measurement is not necessary to perform the Maximum Power Point Tracking (MPPT) control of dc energy source, such as the thermoelectric...
This paper studies the digital controlled dc-dc converter which employs the neural network in coordination with PID control. Especially, we focus on the problem of overcompensation to the transient response of the output voltage in the dc-dc converter by the neural network control. Our previous studies suggested that the neural network control is effective to improve the transient response of the...
Voltage-type sources such as grid, constant-voltage-regulated power supplies, and storage batteries have dominated as input sources for power electronic converters leading to development of multitude of different power stages dedicated for such input sources. The growing application of renewable energy sources has revealed that there are also current-type input sources such as e.g. photovoltaic generator...
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