Maximum Power Utilization Research Articles

A self‐adaptive communication‐free control scheme of islanded PV‐storage microgrids

AbstractFor the problem that traditional droop control cannot maintain the maximum output power of photovoltaic (PV) units, this work proposes a self‐adaptive communication‐free control scheme for the islanded PV‐storage AC microgrids. The proposed control enables the maximum power point tracking‐based output active powers of PVs by adaptively adjusting P‐f/Q‐V droop coefficients. It also facilitates adaptive allocations of reactive powers based on the available capacities of PVs and storage modules. The key characteristics of the proposed control strategy are summarized as follows: 1) PV units are controlled as voltage sources, which could participate in the voltage/frequency regulation to a certain extent; 2) maximum power utilization of PVs is obtained; 3) adaptive allocations of reactive powers are realized based on the maximum available capacity of PVs and storage modules. Subsequently, the stability analysis of the proposed self‐adaptive communication‐free control strategy is verified. Finally, the validity of the proposed self‐adaptive communication‐free control method is validated through simulations conducted using MATLAB/Simulink.

Closed-Loop Current Control Extended to Six-Step Operation With Varying Sample-Control Frequency for PMSM Traction System

Six-step operation can enhance the torque output capability and maximum power utilization and decrease the switching frequency for the PMSM traction system. The main problems of closed-loop current control extended to six-step operation are voltage error disturbances from current controller windup and low-order harmonics current under the low ratio of switching frequency to fundamental frequency. The problem of low-order harmonics current is alleviated by the hybrid synchronized PWM (HSPWM) schemes, but the sample-control frequency is time-varying with speed and fluctuated to keep synchronization. A complex vector current controller (CVCC) with time-varying and stable active resistances to improve the disturbance rejection, including delay time compensation and anti-windup, is designed to be combined with HSPWM. The accurate torque control and closed-loop current control extended to six-step operation are realized. Simulations and experiments are carried out to validate the effectiveness of the proposed control scheme.

Effect of flight level to maximum power utilization for PEMFC/supercapacitor hybrid uav with switched reluctance motor thruster

In this study, the performance of a fixed-wing PEMFC/SC hybrid UAV with an SRM thruster is investigated by different flight levels. Flight levels negatively affect the PEMFC due to changing ambient conditions such as air temperature and pressure. Hence, the international standard atmosphere (ISA) model for PEMFC voltage-current-power ratings is derived with 100 m intervals for 0–7500 m. The demanded electrical power by UAV increases at high altitudes due to the compressor used for air pressurization of PEMFC. Therefore, a maximum power point tracking (MPPT) model of PEMFC should be utilized in case of overshooting the maximum power level that can be provided. While the main power source of the UAV is PEMFC, the auxiliary power source is SC. The SC is preferred for DC bus voltage stabilization, avoiding maximum power point overshoot, and preventing high instantaneous current that shortens the lifespan of PEMFC. The proposed UAV model is verified at MATLAB/Simulink and the results prove that the system is satisfying.

A smart bi-objective two-stage algorithm for optimal transmission switching without islanding

In a deregulated environment, optimal transmission switching (OTS) plays an important role in coordination among power generating companies (GENCOs) and transmission company (TRANSCO) by minimizing operating costs. This paper solves ac OTS (ACOTS) in two different stages sequentially with ac optimal power flow (ACOPF) and transmission switching through ac power flows (TS-ACPF) for optimal power generation and efficient power transmission, respectively. The mutual dependency along with the coordination among these optimal problems are treated intelligently by adopting a metaheuristic based two-stage algorithm with a multi-objective approach to achieve an effective solution through maximum utilization of power in the existing system or for future expansion planning. Production cost optimization problem is taken care of in the first stage while transmission loss is optimized in the second stage with successive iterations of the proposed algorithm. MATLAB simulations to optimize both transmission loss and production cost for both the IEEE-30 bus system and the Indian Utility 62-bus real system are experimented. Results are provided to validate the proposed technique which satisfies several cases of load variations, N − 1 standards and other combinations of stressed security constraint conditions. The detailed investigation of the results prove the effectiveness of the proposed intelligent two-stage method over the existing methods in terms of automatic and cost-effective bi-objective solution relying on the flexibility of switching strategy and security by avoidance of islanding without any manual interaction in between.

Energy Efficient Data Gathering Technique Based on Optimal Mobile Sink Node Selection for Improved Network Life Time in Wireless Sensor Network (WSN)

The utilization of mobile sink in spite of its points of interest carries new difficulties to WSNs. The principle disputes are the position update of sink node to the hub. Every sensor hub should know about the sink position all together that it can move its information to the sink. Existing Flooding technique proposed that the portable sink needs to consistently spread its situation all through the system to advise sensor hubs regarding the sink position. In any case, visit position refreshes from the sink can prompt both maximum power utilization and amplified crashes in the network. To diminish the updation of sink position, different types of routing structures can be utilized. A routing mechanism dependent on the mobile sink is effective if it limits the power utilization and delays in the system network. The primary intention of the study is to design an energy embedded routing protocol based on optimal updation of the mobile sink. Here, the most recent sink position will be spared in the hubs developing the implicit environment. Accordingly, in Embedded routing, the position of the sink node is proliferated to the sensor hubs situated at the discs instead of the solicitation of hubs in the system. The remainder of the hubs can locate the most recent sink position by forwarding solicitation information to the closest disc. Based on the received information, the receiver of the message is identified. This will be performed by optimal fuzzy based clustering technique. The optimization can be done by Oppositional grey wolf optimization (OGWO) algorithm. The efficiency is analyzed by maximum network lifetime, minimum delay etc. The results will be analyzed and compared with existing routing protocols to ensure the efficiency.

Bifurcation Analysis and Chaos Control of a Fractional Order Portal Frame with Nonideal Loading Using Adaptive Sliding Mode Control

We investigate the chaotic oscillations in a fractional order model of a portal frame with nonideal loading. The bifurcation of the fractional order portal frame system for parameters and fractional orders are investigated. Bicoherence analysis shows the existence of quadratic nonlinearities. Fractional order adaptive sliding mode controllers are designed to suppress the chaotic oscillations with uncertain parameters. Power efficiency analysis of the FPGA implemented control scheme shows the maximum power utilization in the fractional order showing the largest Lyapunov exponent.

A Flexible PV-Powered Battery-Charging Scheme for Electric Vehicles

ABSTRACTThis paper presents a new design for a low-impact, fully controlled, and flexible self-adjusting DC side pulse-width modulation (PWM)-hybrid modulated filter compensation (HMFC) scheme for multi photovoltaic-arrays utilized for vehicle-to-grid battery-charging electric vehicle schemes. The flexible HMFC scheme developed by the first author as a member of dynamic hybrid capacitor compensation and filtering scheme is robust and effective as it ensures maximum energy utilization and low inrush current transients. In addition, it provides transient voltage damping for a stabilized common DC interface bus to the battery charger. The new flexible controller uses a regulated multi-loop error-driven, error-scaled, and de-coupled hybrid mode charging controller for the PWM switching scheme along with two MOSFET/IGBT (Metal Oxide Semiconductor Field Effect Transistor/Insulated Gate Bipolar Transistor) complementary switches based on ratings and are cascaded for proper voltage and current photovoltaic (PV) arrays utilized. The dynamic error-driven controller ensures reduction in inrush current and transient voltage conditions as well as compensation for cloudy and shadowy conditions by equalizing the maximum power utilization of the two PV arrays. This will ensure efficient PV solar-system energy utilization as well as fully de-coupled source-load operation for the new proposed multi modal Li-ion battery-charging controller. The multi-regulator error-driven proportional integrated derivative controllers with newly added acceleration and fast response auxiliary loops ensure efficient fast charging as well as common DC-bus stabilization under load excursions, temporary faults, and battery hybrid voltage-current-power (V-I-P) charging modes. The hybrid switched/modulated capacitive-filter compensator ensures limited current excursions for transient DC voltage conditions.

Improvement of Power Quality for Microgrid using Fuzzy Based UPQC Controller

<p>Generally, the power systems are mainly effected by the continuous changes in operational requirement and increasing amount of distributed energy systems. This paper proposes a new concept of power-control strategies for a micro grid generation system for better transfer of power. The micro grids are obtained with the general renewable energy sources and this concept provides the maximum utilization of power at environmental free conditions with low losses; then the system efficiency is also improved. This paper proposes a single stage converter based micro grid to reduce the number of converters in an individual ac or dc grid. The proposed micro grid concept can work in both stand-alone mode and also in grid interfaced mode. The distortions that occur in power system due to changes in load or because of usage of non-linear loads, can be eliminated by using control strategies designed for shunt active hybrid filters such as series and shunt converters. A conventional Proportional Integral (PI) and Fuzzy Logic Controllers are used for power quality enhancement by reducing the distortions in the output power. The simulation results are compared among the two control strategies, that fuzzy logic controller and pi controller.</p>

A Review of Optimal Energy Management Strategies for Hybrid Electric Vehicle

Presence of an alternative energy source along with the Internal Combustion Engine (ICE) in Hybrid Electric Vehicles (HEVs) appeals for optimal power split between them for minimum fuel consumption and maximum power utilization. Hence HEVs provide better fuel economy compared to ICE based vehicles/conventional vehicle. Energy management strategies are the algorithms that decide the power split between engine and motor in order to improve the fuel economy and optimize the performance of HEVs. This paper describes various energy management strategies available in the literature. A lot of research work has been conducted for energy optimization and the same is extended for Plug-in Hybrid Electric Vehicles (PHEVs). This paper concentrates on the battery powered hybrid vehicles. Numerous methods are introduced in the literature and based on these, several control strategies are proposed. These control strategies are summarized here in a coherent framework. This paper will serve as a ready reference for the researchers working in the area of energy optimization of hybrid vehicles.

Six-Step Operation of PMSM With Instantaneous Current Control

Six-step operation has many advantages in permanent-magnet synchronous machine (PMSM) drives such as maximum power utilization and widened flux-weakening region. However, due to the maximum utilization of inverter output, saturation of current regulator makes it difficult to maintain instantaneous current control capability. Accordingly, in most of conventional research studies, the six-step operation has been implemented by voltage angle control without current regulation, whose dynamic performance is quite unsatisfactory. This paper proposes a control scheme for the six-step operation of PMSM with enhanced dynamic performance of current control. By collaborative operation of dynamic overmodulation, flux weakening, and a technique for enhanced dynamic performance, the six-step operation is realized without losing instantaneous current control capability. Simulations and experiments are carried out to verify the effectiveness of the proposed control scheme. The experimental results show 17% extension of the constant torque region and 27% enhancement of torque capability at three times of the base speed.

Energy-delay based provisioning for large datacenters

It is challenging to determine the optimum number of servers required to provision for large online applications because of the conflicting mandates of (a) achieving peak performance needs and (b) minimizing unused datacenter power and capacity. Since Online Services application loads are unpredictable, datacenter operators often conservatively provision for maximum power utilization by characterizing workloads for peak load performance. In contrast, we aim to optimize the service capacity per total cost of ownership (TCO) of an Online Service datacenter deployment by characterizing the energy-delay properties of large scale datacenter workloads. We show that the peak load performance is not the energy efficient point of operation for most applications. We choose two industry-strength workloads (Internet Search and D-Process) and analyze their energy-delay behavior under varying loads. We then calculate the optimal operating point for the specific large-scale application and provision datacenter energy and capacity based on the energy-delay curves. In contrast to workload-based peak power provisioning, we show a 7% benefit in Service Capacity-per-TCOdollar for the energy-delay characterization methodology in our cost analysis for Online Services Applications.

Abstract only

It is challenging to determine the optimum number of servers required to provision for large online applications because of the conflicting mandates of (a) achieving peak performance needs and (b) minimizing unused datacenter power and capacity. Since Online Services application loads are unpredictable, datacenter operators often conservatively provision for maximum power utilization by characterizing workloads for peak load performance. In contrast, we aim to optimize the service capacity per total cost of ownership (TCO) of an Online Service datacenter deployment by characterizing the energy-delay properties of large scale datacenter workloads. We show that the peak load performance is not the energy efficient point of operation for most applications. We choose two industry-strength workloads (Internet Search and D-Process) and analyze their energy-delay behavior under varying loads. We then calculate the optimal operating point for the specific large-scale application and provision datacenter energy and capacity based on the energy-delay curves. In contrast to workload-based peak power provisioning, we show a 7% benefit in Service Capacity-per-TCO-dollar for the energy-delay characterization methodology in our cost analysis for Online Services Applications.

Building-integrated solar photovoltaic systems—a hybrid solar cooled ventilation technique for hot climate applications

The paper presents two low-cost photovoltaic utilization schemes (1–50 kW) for ventilation and air conditioning loads. Both schemes can be controlled by novel dynamic on-line power tracking regulator. This ensures maximum power utilization and energy efficiency under varying conditions of solar insolation levels. The system could be used to conserve electric energy through the decrease of electric demand particularly in developing countries. In addition, the system offers benefits in other areas such as indoor enhanced air quality.

Optimum conventional computer aided process planning

The paper presents an optimum computer aided process planning program which is developed for the Aluminum Company of Egypt. It is concerned with process sheet generation in the AutoCAD environment for particular operations on any machine tool without restriction on the number of machines used or the type of machine at any given instant. All needed machines, tools and materials are imbedded in the program. The program includes all the necessary operations that can be carried out on the Turning, Boring and Milling machines. The program minimizes user interaction by using expert defaults, menus, and dialog boxes. The defaults are calculated optimum values of speed (rpm), feed, and depth of cut for maximum power utilization in roughing and optimum attainment of surface finish and minimum time of operation. The results of the program indicate a saving of 20 to 50 percent in total time of production.

Analysis of the operational reliability of a power-generating unit with a BN-600 reactor during the period 1980–1993

The high quality of the design and the additional improvements to separate units of the main equipment and systems at the initial stage of operation (first main circulation pump, steam generators, safety and control system) ensured reliable operation of the power-generating unit. The reliability indicators are as follows (%): the installed-power utilization factor, the technical utilization factor, and the availability factor were 68.7, 75.7, and 97.2, respectively. The maximum power utilization factor of 77% was achieved in 1988. The safety limits set by the reactor design were not exceeded during the disruption of normal operation of the power-generating unit as a result of equipment failures and personnel errors. The largest number of disruptions (∼75%) occurred during 1980–1986, the average number of disruptions per year was ∼7, and four cases per year occurred in 1987 to 1990. During the most recent period (1988–1993) disruptions of normal operation of the unit (21 cases) were connected mainly with failures of the turbogenerators (five cases) and equipment failures in the third loop (three cases).

The automatic welding-machine starter and its relation to maximum utilization of power and facilities

The automatic welding-machine starter and its relation to maximum utilization of power and facilities

The Automatic Welding-Machine Starter and Its Relation to Maximum Utilization of Power and Facilities

MANY electric-arc-welding applications are of such a nature that the welding machine is running with no load for a large percentage of the operating time. With this low utilization factor or “arc time,” no-load power consumption becomes an appreciable item. In plants employing many machines there will be long leads between the machines and the work, either by necessity or for convenience. Under these conditions, the practicability of expecting the operator, or welder, to turn his machine on and off each time he plans to weld is certainly very remote. The automatic welding-machine starter has been developed to shut down the machine during the normal no-load running periods. Automatic starters have been in operation under average shipyard welding conditions for the past few months. Application of the automatic starters effects a very appreciable saving in power cost, about 25 per cent or more. In addition, a marked reduction in average demand on distribution systems is realized so that additional machines, up to 75 per cent, may be added without further power facilities expenditure.