September 11th

Effects of Source Voltage Harmonics on Power Factor Compensation in AC Chopper Circuits

In recent years, the detailed modelling of power electronic devices and their behaviours on various system conditions are a great concern of the power industries and customers. One of the widely proliferated such devices is the triac controlled ac choppers. Although these types of devices have important application areas, their poor power factor is the main obstacle for the large scale implementation in power systems.

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Transfiguration of supplied-by-HV/MV transformer network to the supply radius

A HV/MV transformer supplies a few power lines of known parameters and loads. These power lines can be substituted with the supply radius, at the end of which there is the equivalent load-receiver representing the entire load being transmitted by the transformer. The R and X parameters of this substitute supply radius are needed to calculate adjusting parameters of the voltage regulator which controls the HV/MV transformer. The presented method enables simple determining of the supply radius parameters R and X.

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World's first tidal stream generating system

1.2 MW plant installed off the coast of Northern Ireland

A new type of renewable energy has been connected to the European grid: tidal energy turbines. The SeaGen Tidal System has been installed in the Strangford Narrows, about 400 metres off the coast of Northern Ireland, by Marine Current Turbines Ltd (MCT). The installation was completed last April and the generators were successfully connected to the grid on 17th July.

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September 9th

Voltage quality improvement using DVR

The problem of voltage sags and Swells and its severe impact on sensitive loads is well known. To solve this problem, custom power devices are used. One of those devices is the Dynamic Voltage Restorer (DVR), which is the most efficient and effective modern custom power device used in power distribution networks. Its appeal includes lower cost, smaller size, and its fast dynamic response to the disturbance. This paper describes DVR principles and voltage restoration methods at the point of common coupling (PCC ).

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September 8th

Computer-Based Voltage Dip Assessment in Transmission and Distribution Networks

Digital simulation is a powerful mean to predict the voltage dip performance of a power network. Voltage dip characteristics can be accurately reproduced using present simulation tools and a stochastic prediction procedure that could incorporate the random nature of the voltage dip causes and the behaviour of sensitive equipment during this type of events.

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September 6th

Active Earthing System to Optimise Power Quality in MV Networks

Neutral treatment is a key issue when a MV network is designed. Requirements of insulation and safety have to be met whilst guaranteeing rapid fault detection, location, arc suppression and tripping -if necessary- within a proper timing. The values of overvoltages and fault currents expected in the network are crucial, since they affect Power Quality parameters, namely interruptions and voltage dips.

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Development of a Photovoltaic Array Emulator System based on a Full-Bridge Structure

Nowadays solar photovoltaic technology is becoming more and more important every day. Manufacturers and laboratories dedicated to photovoltaic (PV) equipment research and development are arising continuously, and so are their needs of having appropriate test equipments.

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September 5th

Voltage Sag Source Location Based on Voltage Measurements Only

This paper introduces an alternative method for voltage sag source location based on voltage information only. The source is located considering the sag magnitude at the primary and secondary side of a transformer. A comprehensive review of previously proposed methods based on voltage and current measurements is presented. The performance of the proposed method is compared with the previous ones using PSCAD /EM TDC on a model of a regional network including transmission and sub-transmission levels.

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September 4th

Hybrid UPS Based on Supercapacitor Energy Storage and Adjustable Speed Generator

This paper presents a hybrid on-line UPS system (H-UPS). The system is based on an on-line (double conversion) UPS, consisting of two controlled energy storage systems. The first one is a static energy storage system based on supercapacitor bank. The second energy source is adjustable speed generating system supplying DC link voltage. A control concept of the UPS operation, according short and long failure of the supply utility voltage is developed. The 5 kW H-UPS is designed, built and tested.

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Sony City uses waste heat from sewage treatment plant

Heat pump reduces energy and water consumption dramatically

When talking about a heat pump, most people will think of a system taking heat at low temperature from the ground, the air, or a water reservoir. However, other configurations are possible. Sony City, the new Sony headquarters in Tokyo, receives heating and cooling from a heat pump connected to a nearby sewage water treatment plant.

By recycling the heat from the sewage plant, the system achieves a Coefficient of Performance (COP) of 5.19, which is exceptionally high. It means that the building receives 5.19 units of energy for each unit of primary energy that is consumed.

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