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This paper proposes a new half-bridge inverter based active power quality compensator (APQC) for electrified railways with a three-leg inverter. The first-leg is connected to α-phase, and the second-leg is connected to β-phase. The midpoint of two capacitors on the dc side is connected to the ground line. These two half-bridge inverters exchange the active power on the each feeder each other through...
This paper proposes a single phase full bridge PWM rectifier with load current feedforward. The proposed approach has some advantages, including a quick response for the load fluctuation, reduced the number of sensors and simplified control, as compared with the conventional methods. From experimental results, it is clarified that the proposed control method is effective and useful.
Smart grids offer a wide application domain for power electronics. In fact, every distributed energy resource (DER) includes an electronic power processor (Switching Power Interface, SPI) which controls the currents drawn from the grid and can be driven to optimize the power flow, improve voltage stability and increase distribution efficiency. For these aims, such distributed SPIs must perform cooperatively...
In this paper, a new type of controller is proposed for series connected PV inverter for grid voltage compensation. The inverter operates during the day time as an active power compensator as well as load voltage regulator under grid voltage sag, swell or even under normal condition. The compensating voltage provided by the inverter is added vectorially in series with the grid voltage in such a way...
The influence of instantaneous voltage drops in the power systems due to lightning have become a significant issue, because manufacturing facilities have become highly sophisticated and intelligent. On the other hand, it may be impossible to completely avoid instantaneous voltage drops in power systems caused by natural phenomena. In order to solve the problem of the voltage drops, this paper presents...
In this article the distortions caused by the pulsed operation of a group of power supplies (PS) feeding an Electrostatic Precipitator (ESP) are investigated, and means for improving the line quality are proposed. In order to reduce the Total Harmonic Distortions (THD) of the line current and also improve the loading balance between the phases, the pulses of the individual power supplies are scheduled...
A voltage disturbance generator for the test of a microgrid is described. The generator provides the function of voltage sag, unbalance, outage, and phase jump of the output voltage. The proposed generator has good features of high reliability, low cost, simple structure, high efficiency, and easy implementation. The main components of the generator are SCR thyristors and transformers, which provides...
A nine-switch power converter having two sets of output terminals was recently proposed in place of the traditional back-to-back power converter that uses twelve switches in total. The nine-switch converter has already been proven to have certain advantages, in addition to its component saving topological feature. Despite these advantages, the nine-switch converter has so far found limited applications...
Fossil fuel generators like diesel and natural gas gen-sets are the mainstays of microgrids for reliable power generation. This paper investigates different methods or modes to maximize fuel efficiency of the online generators in a microgrid where a substantial portion of the total generation capacity comes from fossil fuel generators. Energy storage is used to facilitate high efficiency operation...
After the status quo and features of railway systems in Japan are introduced, the research map of railway technologies foreseeing the year 2030 society is given. The subjects related to power electronics technologies are selected and explained with existing states of developments of vehicles, ground facilities and new type of systems. Practical applications depend strongly on the realization of high...
Power electronics technology is becoming an increasingly important aspect of today's power distribution system. It is the key interface to connect distributed energy resource (DER) to the utility and the local loads. With the increased penetration of power electronics based distributed generation (DG) systems, the power quality requirements are becoming more stringent. On the other hand, if controlled...
This paper presents a new synchronization system that can be used to extract real time information such as the amplitude, phase and frequency of the fundamental component from an input power signal. The synchronization system is based on a zero-crossing (ZC) and peak-detection (PD) algorithm. Among its advantages, the Zero-Crossing Peak Detection (ZCPD) system performs well in the presence of input...
Power converters are an important component of microgrids. They help interconnect renewable sources and energy storage systems in a microgrid. In addition, power converters can provide ancillary services to improve power quality within the microgrid and facilitate interconnection with the electrical power system. The size and the number of the power converters required will depend on the fluctuating...
For high power grid connected devices with power quality compensation function, directly paralleled 3-phase 4-wire inverter is the most simple configuration to chose, but the zero sequence current is always a big problem that have to deal. This paper established the phase-leg averaging model of this type system, developed the dynamic model of zero sequence current, then indroduced a simple method...
In recent years, voltage and current harmonic problems by the remarkable development of static power converters with nonlinear characteristics have been one of the significant subjects. The authors propose the three phase power quality compensator with five leg circuit by indirect power conversion method. This system can compensate the line voltage harmonics by the series inverter and the load current...
In recent years, multilevel technology has become an effective and practical solution for moderate and high voltage application field. In all multilevel technology, cascade multilevel inverters have become the major circuits used in power quality conditioners. Evidently, the voltage balancing problem of DC capacitors of cascade inverters is a key problem to the power quality conditioners. This paper...
This paper presents a digital complicated control method for an active voltage quality regulator (AVQR). The scheme combines repetitive and multi-loop control, utilizing repetitive control to guarantee good steady-state performances and dual-closed-loop as well as feed-forward control to improve dynamic response. Hence, it can achieve precise control for the output voltage waveform and fast dynamic...
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