Impact of hybrid renewable energy systems on short circuit levels in distribution networks

The effects of the distributed generation can be classified as environmental, technical and economical effects. It is playing a very vital role for improving the voltage profiles in electrical power systems. However, it could have some negative impacts such as operating conflicts for fault clearing and interference with relaying. Distribution system is the link between the utility system and the consumer. It is divided into three categories radial, Loop, and network. Distribution networks are the most commonly used to cover huge number of loads. The power system reliability mainly depends on the smooth operation and continuity of supply of the distribution network. However, this may not always be guaranteed especially with the introduction of distributed generation to the distribution network. This paper will examine the impact of hybrid renewable energy systems (using photovoltaic and doubly fed induction generators) on short circuit level of IEEE 13-bus distribution test system using ETAP software

A maximum power point tracking for a photovoltaic system based on optimum sinusoidal modulated control pulses

Photovoltaic systems have grown rapidly in the last few decades. This growth has enhanced research about this technology, focusing on reducing cost and improving efficiency. Maximum power point tracking (MPPT), which increases the overall efficiency of a PV system, is a main part of a PV system. In this paper, some MPPT methods have been critically reviewed. Fractional open-circuit voltage has been investigated. The approach of a separate PV array to obtain the open circuit voltage (Voc) is adopted. The proposed idea in this paper is based on optimising the control pulses for the DC-DC converter. The generation of control pulses is based on sinusoidal modulated pulse width modulation (SPWM). The output from the DC-DC converter is then fed into a low frequency square wave voltage-fed inverter circuit. The output is a fine sinusoidal waveform, although the inverter operates at a low frequency. The block diagrams and the results are presented

Critical review of converter topologies for switched reluctance motor drives

This paper represents an overall literature review of SRM convenient drive circuit topologies with the proposal of a new topology utilizing switched capacitance circuit. The known topologies of SRM drive circuits were critically reviewed and compared. The main configurations and classifications of SRM and the principle of switched capacitance circuit with double capacitors, double switches are reviewed as well

A new control technique for active power filters using a combined genetic algorithm/conventional analysis

In this paper, the computational problems associated with the optimization techniques used to evaluate the switching patterns for controlling variable-characteristics active power filters are presented and critically analyzed. Genetic algorithms (GAs) are introduced in this paper to generate a fast and accurate initial starting point in the highly nonlinear optimization space of mathematical optimization techniques. GAs tend to speed up the initialization process by a factor of 13. A combined GA/conventional technique is also proposed and implemented to reduce the associated computational burden associated with the control and, consequently, increasing the speed of response of this class of active filters. Comparisons of these techniques are discussed and presented in conjunction with simulation and practical results for the filter operation

A novel three-phase UPS system with a single-phase resonant HF link

This paper presents a new three-phase uninterruptible power supply (UPS) system based on a single-phase resonant high frequency (HF) link and a single-phase transformer. The three-phase output voltage is constructed and regulated from a three-phase cycloconverter fed from the constant amplitude, constant frequency link voltage. The generation of a novel switching stategy for the three-phase cycloconverter is presented. The simulation of the proposed system is carried out and verified with experimental results

Variable var compensator circuits

A family of two reactive-power compensator circuit is presented. A general model of some basic linear elements and switching function blocks is developed first. Then the two proposed compensator circuits are derived from the generalised model. The proposed circuits are capable of supplying leading as well as lagging reactive currents in stepless variation without using an inverter configuration. The switching frequency is in the range of 2.5 kHz and the largest capacitor utilised does not exceed 60 muF. The generated reactive current, in either the leading or lagging modes, contains less than 2% total harmonic distortio

Power optimization for a hydrocarbon industrial plant using a genetic algorithm

In this paper, a genetic algorithm (GA) is considered for optimizing electrical power loss for a real hydrocarbon industrial plant as a single objective problem. The subject plant electrical system consists of 275 buses, two gas turbine generators, two steam turbine generators, large synchronous motors, and other rotational and static loads. The minimization of power losses (J1) objective is used to guide the optimization process, and, consequently, the injected power into the grid (PRInject) is increased. The results obtained demonstrate the potential and effectiveness of the proposed approach to optimize the power consumption. Also, in this paper a cost appraisal for the potential daily, monthly and annual cost saving will be addressed

Impacts of domestic load and electric vehicles on domestic consumption in UK

This paper highlights domestic consumption of electricity in UK and effect of electric vehicles on the domestic demands. Also, consider the trends and growth of domestic electricity demand and the implication of using the electric vehicles. One challenging factor is the management of the domestic load electricity demand on the electric vehicles. To this end, this paper investigates new management technology technique that can be used in domestic sector. The key point to tackle this problem is to outline pattern shape of the electricity usage per individual household. However, lack of information on individual usage per consumer is complicating the path to the new solutions. Data were collected from daily energy consumption and energy peak demands from UK electricity industries. In additional the research explores the effect of recently introduced UK energy plan to reduce the CO2 emission and how this affects usage of the electric vehicle. The proposal in the new solutions includes the use of renewable energy sources such as solar panels and batteries banks for domestic supply. This would go a long way to reducing electricity demand as well as reduce CO2 emission from domestic sector

A Practical Application of Low Voltage DC Distribution Network Within Buildings

Science & Technolog

Restoration of an AFM Height Image using a Deflection Image at Different Scanning Speeds

The principle of the Atomic Force Microscope involves scanning an object using a probing tip that is mounted on the free end of a micro mechanical cantilever. While the sample is scanned horizontally the cantilever deflects. The deflection of the cantilever can be sensed among several methods. For instance, optical beam deflection where this method is often used because of it’s simplicity. While the scanning process of the sample stage, the detected deflection is compared with the set point deflection. Then, the error signal which is the difference between the detected and set point deflection is minimized by moving the sample stage in the Z – direction. At a set point value this closed –loop feedback operation can maintain the cantilever deflection and hence the tip – sample interaction force. The sample surface is approximately traced by the resulting 3D movement of the sample stage. Therefore, usually the topographic image can be formed from the electrical signals which are used to drive the sample stage scanner in the Z- direction. In this paper, the AFM topographic image is constructed using values obtained by summing the height image that is used for driving the Z- scanner and the deflection image with a weight function that is close to 3. The value of has been determined experimentally using trail and error. This method gives more faithful topographic image