The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
It is shown that application of adjustable sources of reactive power based on magnetically controlled shunt reactors and capacitor banks in 110-500 kV grids allows to substantially lower the damage from power supply interruption, to reduce the need of electrical grids construction by maximizing power transmission capacity of existing lines, to improve the quality of power supply to end users, and...
Ancillary services are some operational reserved services procured by the Transmission System Operator (TSO) for keeping a balance between supply and demand, stabilizing the transmission system and maintaining the power quality on an economical basis in any competitive electricity market environment. This paper discusses different types of ancillary services and their characteristics and challenges...
The global demand for energy is increasing at a breathtaking pace. This sharp increase in world energy demand will require significant investment in new power generating capacity and grid infrastructure. Considering the present energy scenario and the degrading environmental conditions, distributed generation seems to be a promising option. Distributed Generation generally refers to small-scale electric...
Islanding phenomenon is a problem for Distributed Generator (DG) based networks leading to troubles in voltage and frequency control and other power quality issues. This paper describes the development of a method based on Discrete Wavelet Transform (DWT), in order to detect islanding for DGs. This method detects the islanding state only by evaluating the terminal current of DGs. Hence, different...
Active and reactive power flow control and power quality improvement of a two level Voltage Source Converter (VSC) based High Voltage Direct Current (HVDC) system operating at fundamental frequency switching is proposed in this paper. Two converter stations used in this HVDC system consists of two level VSC configuration to achieve active and reactive power control with fundamental frequency switching...
In a reliable power system one of the most important requirements is to maintain the voltage at consumer premises within permissible ranges to ensure high quality of customer service. Since the voltage profile is consistently varied by load fluctuations hence it should be controlled by voltage regulators. Voltage stability and power quality of electrical systems depend on the proper voltage regulation...
Increasing non-linear loads cause various undesirable effects and power quality problems on utility supply, like low system efficiency, poor power factor, derating of power supply equipments, disturbance to other consumers and interference in nearby communications networks etc. This work proposes a parallel power processing scheme to improve the power quality of uncontrolled diode bridge rectifier...
Voltage sag is one of the major power quality problem which results in a failure or a mis-operation of end use equipments. Sensitive industrial loads and Utility distribution networks all suffer from various types of outages and service interruptions which can cost significant financial loss per incident. The aim therefore, is to recommend measures that can improve voltage sag. In this paper a method...
Three phase electrical machines are normally exposed to lowered levels of supply voltage quality conditions which can appear simultaneously due to voltage disturbances of overvoltage or undervoltage, voltage unbalance and voltage waveform distortions. These voltage disturbances can cause effects of seriously overheating winding insulation resulting in degradation and reduced lifespan of the machines...
This paper investigates the use of a static synchronous compensator (STATCOM) to mitigate the voltage fluctuations and improve fault ride-through capability of wind farm with fixed speed induction generators. In order to assure STATCOM of running safely and reliably in both normal and faulty conditions, a novel control strategy which combines negative-sequence voltage feed-forward control with conventional...
This paper presents a new control strategy for adaptive hysteresis current control based power quality studies for an induction motor to eliminate harmonics and to compensate the reactive power. The adaptive hysteresis band current controller changes the hysteresis bandwidth according to modulation frequency, supply voltage, dc capacitor voltage and slope of the reference compensator current wave...
Multibrid wind power generation system (MWPGS) has aroused more and more attention for its high energy conversion efficiency, high reliability, and flexible grid-connected power control. In order to achieve the decoupling regulation of the active and reactive power during the normal operation and enhance its capability of low voltage ride-though (LVRT) during grid voltage sag, a unified control strategy...
Electrical storage devices can be very useful in electrified mass transit and in particular in trolleybus lines and tramways. In fact, storage devices are capable of supporting the line voltages of old lines, avoiding the opening of minimum voltage protective relays, especially when the new generation vehicles of greater power circulate. Among electrical storage devices, supercapacitors seem to be...
Supplying power for DC energy storage unit of power quality compensator by rectifier will produce much harmonic and decrease power factor. Active power factor correction technology can resolve the problem, but it will bring much switching loss and put forward higher requirements to the frequency and stress of power device. It proposed soft switching power transformation technology to control switching...
After the synchronous interconnection of Turkish Power System to ENTSO-E CESA (former UCTE) System, inter-area oscillations in the range of 0.15 Hz are prone to occur, according to simulation studies. Therefore, some preventive measures should be considered in order to ensure stable operation of the network after the interconnection. This study summarizes the effects of following measures based on...
Wind generation has been the fastest growing power source over the past decade and this growth is forecasted to continue. The new trend is adding large wind plants to achieve economy of scale. As large wind plants are likely to contribute to significant shares of the energy, they also bring new challenge in system operation. These challenges include connection of large wind farms to weak grids, securing...
High penetration levels of distributed photovoltaic (PV) generation on an electrical distribution circuit may degrade power quality due to voltage sags and swells caused by rapidly varying PV generation during cloud transients coupled with the slow response of existing utility compensation and regulation equipment. Fast-reacting, VAR-capable PV inverters may provide the necessary reactive power injection...
This paper presents a three-phase Active Power Conditioner to improve power quality in microgrids based on renewable energy. A microgrid is a weak electrical grid which can be easily subject to disturbances. The Active Power Conditioner (APC) presented in this paper acts as an interface between renewable energy sources and the AC bus of a microgrid and uses an improved control strategy, which makes...
Smart-Grid has emerged as an important requirement to achieve high quality voltage supplied to customers. Within the context of general power quality indicators, a common problem found in distribution systems is the unbalanced voltage. Usually, to solve this type of disturbance, a step voltage regulator can be used to obtain voltage amplitude compensation. However, for many applications, this device...
Single- and three-phase topologies of the bi-directional a.c. controller, comprising power MOSFET embedded four-quadrant switch (4QSW) realizations operating in high-frequency chopping mode are presented. The performance of the controller with inductive load is assessed for power quality. A three-phase, three-wire, wye-connected inductive load is considered and the corresponding gate controls has...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.