Abstract: Power is supplied to an information handling system chipset with a single voltage regulator having dual phases A first phase of the voltage regulator provides power to a low power state power rail in an independent mode to support a low power state, such as a suspend or hibernate state A second phase of the voltage regulator provides power to a run power state power rail in combination with the first phase by activation of a switch, such as a MOSFET load switch, that connects the low power state power rail and the run power state power rail Voltage sensed from both power rails is applied to control voltage output so that the run power state power rail is maintained within more precise constraints than the low power state power rail

Abstract: This paper presents the power management scheme for a power electronics based low voltage microgrid in islanding operation. The proposed real and reactive power control is based on the virtual frequency and voltage frame, which can effectively decouple the real and reactive power flows and improve the system transient and stability performance. Detailed analysis of the virtual frame operation range is presented, and a control strategy to guarantee that the microgrid can be operated within the predetermined voltage and frequency variation limits is also proposed. Moreover, a reactive power control with adaptive voltage droop method is proposed, which automatically updates the maximum reactive power limit of a DG unit based on its current rating and actual real power output and features enlarged power output range and further improved system stability. Both simulation and experimental results are provided in this paper.

Abstract: During voltage dips continuous power delivery from distributed generation systems to the grid is desirable for the purpose of grid support. In order to facilitate the control of inverter-based distributed power generation adapted to the expected change of grid requirements, generalized power control strategies based on symmetric-sequence components are proposed in this paper, aiming to manipulate the delivered instantaneous power under unbalanced voltage dips. It is shown that active and reactive power can be independently controlled with two individually adaptable parameters. By changing these parameters, the relative amplitudes of oscillating power can be smoothly regulated, as well as the peak values of three-phase grid currents. As a result, the power control of grid-interactive inverters becomes quite flexible and adaptable to various grid requirements or design constraints. Furthermore, two strategies for simultaneous active and reactive power control are proposed that preserve flexible controllability; an application example is given to illustrate the simplicity and adaptability of the proposed strategies for online optimization control. Finally, experimental results are provided that verify the proposed power control.

Abstract: The relevance of power quality (PQ) issues has recently augmented because of the increased use of power electronic equipment, which results in a voltage deviation and current waveforms. The PQ monitoring is covered by two main subjects: the development of PQ indices to quantify the power supply quality and the electrical disturbances detection such as harmonics, sags, swells etc., which allows knowing the conditions of the electric power systems. In this study a review of techniques and methodologies developed for PQ analysis and power disturbance classification is presented in order to show their major characteristics.

Abstract: Distributed generation (DG) is increasing in penetration on power systems across the world. In rural areas, voltage rise limits the permissible penetration levels of DG. Another increasingly important issue is the impact on transmission system voltages of DG reactive power demand. Here, a passive solution is proposed to reduce the impact on the transmission system voltages and overcome the distribution voltage rise barrier such that more DG can connect. The fixed power factors of the generators and the tap setting of the transmission transformer are determined by a linear programming formulation. The method is tested on a sample section of radial distribution network and on a model of the all island Irish transmission system illustrating that enhanced passive utilization of voltage control resources can deliver many of the benefits of active management without any of the expense or perceived risk, while also satisfying the conflicting objectives of the transmission system operator.

Abstract: Reactive power plays a significant role in power system operation. However, in reliability evaluation, attention has seldom been paid to reactive power. In conventional power system reliability evaluations, the fixed maximum and minimum values are applied as the reactive power limits of generators. Failures of reactive power sources are rarely considered. The detailed causes of network violations for a contingency are also seldom studied. Real power load shedding is usually used to alleviate network violations without considering the role of reactive power. There are no corresponding reliability indices defined to represent the reactive power shortage in the existing techniques. Reactive power shortage and the associated voltage violations due to the failures of reactive power sources are considered in this paper. New reliability indices are proposed to represent the effect of reactive power shortage on system reliability. The reliability indices due to reactive power shortages have been defined and are separated with those due to real power shortages. Reactive power limits determined by real power output of a generator using P-Q curve have been studied. A reactive power injection technique is proposed to determine possible reactive power shortage and location. The IEEE 30-bus system has been modified and analyzed to illustrate the proposed technique. The results provide system planners and operators very important information for real and reactive power management.

Abstract: In an ON/OFF type isolated DC-DC converter that stores electromagnetic energy in a main transformer during an ON period of a power switch and releases the electromagnetic energy to an output during an OFF period of the power switch, high-speed, highly stable output voltage control without the need for a photocoupler, for which the allowable temperature range is relatively narrow and the current transfer ratio changes over time, is performed. An integrating circuit including a resistor and a capacitor generates a ramp wave, and the ramp wave is superposed on a reference voltage of a reference voltage source Vref through a capacitor. A comparator compares a voltage Vo that is proportional to an output voltage of a converter with the reference voltage on which the ramp wave has been superposed, and transmits an inversion timing signal through a pulse transformer. During an ON period of a power switch, when the voltage Vo that is proportional to the output voltage exceeds the reference voltage on which the ramp wave has been superposed, the comparator is inverted and the power switch is turned OFF.

Abstract: Increased electrical power demands are being experienced on the new generation of aircraft due to an increased reliance on electrical technology such as air conditioning, de-icing systems and electrical flight control actuation. Distribution of power at higher voltages is therefore now being seen in modern aircraft to avoid the penalties incurred due to high wire weights. Voltages have increased past the minimum of Paschen's law resulting in a risk that life limiting partial discharge damage can occur in the insulation systems. This study uses a theoretical analysis backed by experimental results to investigate the optimal operating voltage of a wiring system. In addition it proposes a methodology for optimising the operating voltage level based on an analysis of the power carrying capability of wiring within a fixed volume system and the derivation of the wire weight as a function of voltage. The work done has shown that the optimal operating point for an aircraft power system does not imply the use of the highest voltage possible. A trade-off between wire weight and power transfer is required and furthermore the use of direct current systems can result in higher power transfers than conventional three phase/400 Hz alternating current (AC) systems.

Abstract: This paper presents the design and analysis of both the active and reactive power control of a single-phase voltage source inverter (VSI) for grid-connected photovoltaic (PV) system. The proposed method is based on vector control of power by decoupling control of the active and reactive current components to feed the active and reactive power to the grid. The aim of this research is to control power factor at grid, to improve overall efficiency of transferring power of PV to alternate current power conversion into the grid, and to decrease phase current distortion of VSI. In this work, mathematical model of system has presented in details. The results of simulations of PV system 1kW connected to grid 220V, 50 Hz using MATLAB/Simulink software are also discussed. Simulation results have shown that the grid input power factor is nearly unity, and the distorting of phase current of the proposed system has been reduced, causing the total harmonic distortion for various power conditions falls within 5%.

Abstract: In distributed power generation systems a fast and accurate positive-sequence fundamental grid-voltage frequency and magnitude tracking is required to synchronize grid-connected converter-systems with the mains. In this paper state-of-the-art fundamental grid-voltage detection methods based on the extension of the Synchronous Reference-Frame phase-locked loop with either an additional pre-filter for the phase detection or an extended loop-filter are presented and compared to each other. The performance of these methods is studied in the laboratory environment during harmonic voltage-distortions as well as characteristic grid-faults. Furthermore, a new approach using a combined pre- and extended loop-filter technique to improve the harmonic voltage-distortion rejection abilities is presented and thoroughly verified by measurements. The analysis reveals that the optimal choice of the PLL-methods is a trade-off between the dynamic performance requirements and the accuracy of the grid-voltage tracking during highly distorted grid-conditions. Furthermore, the proposed combined filter approach reveals fast voltage tracking performance with good voltage distortion rejection abilities.

Abstract: To help reduce consumption of fossil fuels, renewable, natural and distributed power sources are being adopted. These alternative energy sources inevitably show fluctuations in the amount of output power, frequency, and voltage. The suppression of such fluctuations is a key issue to avoid disturbances in power grids. A similar situation arises as far as the regulation of in-home power flow is concerned. We focus on the quality of supplied and demanded power in particular. In this paper, an in-home power distribution system based on information of power is proposed. The system is developed in order to integrate power dispatch and communication. The experimental results show the feasibility of new flexible and efficient power management approaches.

Abstract: In this paper the electric yield of DRAM core circuits is investigated by means of a statistical approach that incorporates a hierarchical linear Gaussian model for the DRAM core sensing process and a lognormal distribution model for the DRAM cell leakage. Analytical yield expressions are obtained and found to be dominated by two independent sources-either the lognormal distribution of the cell leakage components or the Gaussian distribution depending on the array structural parameters, parasitic, and the sense amplifier offset voltage. Analytical yield analysis is conducted for several different DRAM architectures and compared to measurements from signal margin analysis and data retention tests. The yield model is found to be very accurate. Thanks to the short computation time, it can be easily applied to the analysis and yield optimization of novel array structures, DRAM cell leakage analysis, sense amplifier offset voltage requirements, and core supply voltage optimization. It also paves the way for the design for yield of other memory circuits.

Abstract: This paper investigates two methods for mitigation of voltage dips and voltage swells in a grid to which a wind energy conversion system (WECS) is connected. The two mitigation methods are the dynamic voltage restorer (DVR) and the static synchronous compensator (STATCOM). The wind energy system employs permanent magnet synchronous generator (PMSG). It is well known that the voltage dips affect the PMSG adversely, leading to unlimited increase in its speed. Hence, quick voltage dip mitigation is required. The responses of both DVR and STATCOM to voltage dips as well as voltage swells are investigated and compared. The control algorithms employed with each device are presented. The need for applying additional filters to suppress harmonic contents of each system (the system employing DVR and that employing STATCOM) is studied. Also, the active and reactive power behaviors in each system during and after fault recovery are investigated. The simulation results compared for voltage dips and voltage sw...

Abstract: In this paper an intelligent fuzzy logic controller is proposed to control the frequency and voltage of a power generating system. The load frequency control (LFC) and automatic voltage regulator (AVR) are installed in each generator to control the real and reactive power flows. Due to rising and falling power demand, the real and reactive power balance is harmed and hence frequency and voltage get deviated from nominal value. This necessitates the need for an intelligent fuzzy controller to generate and deliver power in an interconnected system as economically and reliably as possible while maintaining the voltage and frequency within permissible limits. The conventional PID controllers employed for this task will have zero steady-state error but lead to large deviations in frequency and voltage under varying load conditions. The proposed method overcomes the drawbacks of a conventional fixed gain controller and improvement is achieved in terms of settling time, oscillations and overshoot. The single and...

Abstract: In order to provide a power control device that supplies stable power to a load while deterioration of a storage battery is suppressed, a power control device (105) according to the invention is provided with: an acquisition unit (201) which acquires voltage information of voltage applied to a capacitor that is provided, by way of a first power line and a second power line, between a prescribed generation means and a load, and which acquires deterioration information indicating the deterioration condition of a storage battery connected to the prescribed generation means; a determination unit (202) which compares the acquired voltage information and a prescribed reference voltage to detect a fluctuation component of the voltage applied to the capacitor, and which determines the power that is output to the storage battery in such a way that the fluctuation component of the voltage applied to the capacitor is suppressed; and an instruction value notification unit (203) which notifies the storage battery of a current instruction value corresponding to the power that is output to the storage battery. The determination unit (202) detects the deterioration condition of the storage battery by using the deterioration information, and determines, in accordance with the deterioration condition of the storage battery, the power that is output to the storage battery.

Abstract: Systems, methods, and computer program products for providing an inertial response by a wind power system to power fluctuations in an electrical grid. The system includes a synthetic inertial response generator configured to generate a power offset in response to fluctuations in grid voltage. The power offset signal is generated by determining a quadrature component the grid voltage using an internal reference voltage having an angular frequency and phase angle that is synchronized to the electrical grid by a control loop. The quadrature component is used to determine a synchronous power level. A control loop error signal is produced by the difference between the synchronous power level and the wind turbine system power output. Changes in the grid frequency produce an error signal that is added to the power set point of wind turbine system output controllers to provide a power system inertial power output response.

Abstract: In this paper, a universal active power filter is proposed for harmonic and reactive power compensation in the single-phase to three-phase systems. The proposed configuration solves a typical problem found in remote (or rural) applications, where only a single-phase grid is available and there is a demand to supply three-phase loads. A suitable control strategy is presented to regulate the load voltage, the power factor, and to minimize the voltage and current harmonics simultaneously. Simulated and experimental results are also presented.

Abstract: The capacitor-clamped base cell is presented. Based on the base cell, a novel family of single-stage three-level (TL) ac choppers is proposed. The converters can directly transfer unsteady high ac voltage with distortion into regulated sinusoidal voltage with low THD. The circuit configuration is constituted of a TL converter, and input and output filters. The topological family includes buck, boost, buck-boost, Cuk, Sepic, and Zeta modes. In order to achieve a reliable TL ac-ac conversion, a double transient voltage feedback control strategy of output voltage and the voltage across the clamp capacitor is introduced in this paper. A prototype of a 500 VA 220 V ± 10% 50 Hz ac/180-240 V 50 Hz ac converter is presented with the experimental results to prove that the converters have four improved advantages simultaneously, including the lower voltage stress of power switches, the bidirectional power flow, the low total harmonic distortion of output voltage, and the higher input power factor.

Abstract: Modular multilevel converter (MMC) is a newly emerging multilevel topology for high power applications in recent years. The voltage fluctuation problem of a new MMC topology is studied in this paper. In order to suppress the voltage fluctuation of the floating capacitors, a control method is proposed by injecting high frequency zero-sequence voltage and phase-to-phase circulating currents. It can be used to drive an induction motor with pump/blower-like load at low speed and improve the performance significantly. A low power three-phase five-level prototype is built up to validate this method.

Abstract: Systems and methods are provided for an electrical system. The electrical system, for example, includes a first load, an interface configured to receive a voltage from a voltage source, and a controller configured to receive the voltage through the interface and to provide a voltage and current to the first load. The controller may be further configured to, receive information on a second load electrically connected to the voltage source, determine an amount of reactive current to return to the voltage source such that a current drawn by the electrical system and the second load from the voltage source is substantially real, and provide the determined reactive current to the voltage source.

Abstract: The role of the transmission network in the Power System is to transmit the power generated in the power plants to the load centers and the interconnected power systems. The transmission of electric power has to take place in the most efficient way in addition to providing flexibility in the process. Flexible A.C. Transmission System (FACTS) promotes the use of static controllers to enhance the controllability and increase the power transfer capability. Providing reactive shunt compensation with shunt-connected capacitors and reactors is a well established technique to get a better voltage profile in a power system. Shunt capacitors are inexpensive but lack dynamic capabilities, thus some form of dynamically controlled reactive power compensation becomes essential. This feature is provided by Static VAR Compensator (SVC). The work presented here also compares SVC with fixed capacitor compensation and documents the superiority of SVC using Computer Simulation and its performance for reactive power management and better voltage control.

Abstract: Systems and methods include a voltage transformer connected to a power source. The voltage transformer transforms a high voltage of the power source to a first low voltage signal. Regulators are connected to the voltage transformer, and the regulators receive the first low voltage signal from the voltage transformer and convert the first low voltage signal to a second low voltage signal. A remote device is connected to each of the regulators. The remote device is powered by the second low voltage signal from the regulator to which it is connected.

Abstract: A method for operating a wind turbine and a system for operating a wind turbine are provided. The wind turbine includes a grid side converter and the grid side converter is coupled to a grid via a power line. The method includes determining a wind turbine operation strategy; determining a first active power reference and a first reactive power reference indicating a requested amount of active power and reactive power, respectively, depending on at least the wind turbine operation strategy; measuring a grid voltage of the grid; determining a positive sequence component and a negative sequence component of the grid voltage i.e. a positive sequence voltage and a negative sequence voltage; determining a second active power reference and a second reactive power reference indicating an actual amount of active power and reactive power to be supplied by the grid side converter to the grid, respectively, depending on at least the first active power reference, the first reactive power reference, and the wind turbine operation strategy; generating, based on at least the wind turbine operation strategy, a first parameter and a second parameter which define a proportion of positive sequence current component and negative sequence current component to be injected by the grid side converter in order to supply active power and reactive power in accordance with the second active power reference and the second reactive power reference; generating a current reference based on at least the second active power reference, the second reactive power reference, the positive sequence voltage, the negative sequence voltage, the first parameter, and the 77 second parameter; and supplying, with the grid side converter, active and reactive power to the power line based on the current reference.

Abstract: Grid voltage rise and thermal loading of network components are the most remarkable barriers to allow high number of distributed generator (DG) connections on the medium voltage (MV) and low voltage (LV) electricity networks. The other barriers such as grid power quality (harmonics, voltage unbalance, flicker etc.) and network protection mechanisms can be figured out once the maximum DG connection capacity of the network is reached. In this paper, additional reactive power reserve of inverter interfaced DGs is exploited to lower the grid voltage level by means of location-adaptive Q(U) droop function. The proposed method aims to achieve less grid voltage violations thus more DG connection on the electricity distribution networks can be allowed.