EPQU Magazine - Vol 3 Issue 2

By Fainan Hassan and Math Bollen

This paper proposes a simple DC current chopper combined with the reactive power control, in order to provide specific interactive capabilities for power-electronics interfaced distributed generation units. The chopper provides a dynamic current limitation capability. During voltage disturbances, it can reduce the active current command to allow more reactive current to be injected into the grid. The proposed controller has been implemented for the mitigation of voltage magnitude variations at the connection point. It will be shown that the proposed controller results in better regulation of both grid and DC-link voltages. Moreover, through the proper sizing of the chopper, the fault ride-through capability is increased and a robust distinction is made by the DG unit between ride-through and islanding operation.

By Math Bollen

This paper introduces methods to quantify the impact of wind power and other types of distributed generation on the overvoltage risk. The so-called hosting capacity approach, introduced in the very first issue of this magazine, is used as the basic approach. Both a deterministic and a statistical approach are introduced. The deterministic approach is suitable for generation with a constant production most of the time. However, it is shown that a deterministic approach could easily result in an unnecessary barrier against the introduction of wind power. For any method used to determine the hosting capacity, a serious discussion is needed about overvoltage indices and objectives.

By Daniel Kottick

The Israel Electric corp. deployed a nationwide Power Quality Monitoring System (PQMS). The PQMS monitors the quality of supply of all of its high voltage costumers, as well as a sample of its medium voltage customers. The PQMS monitors both the voltages and the currents. The PQMS has been operational since October 2005. The paper presents preliminary measurement results obtained from the PQMS.

Along with wind power, concentration photovoltaics (CPV) offers one of the most promising utility-scale, renewable energy technology options. CPV has a current system efficiency of 25% and the potential of reaching much higher efficiency. In the right locations, it could provide electricity at cost low enough to be competitive with fossil and nuclear power. Compared to other solar technologies, CPV has the advantage of modularity and very low water needs.

This documentary goes across technology features of CPV. A visit to ISFOC (CPV Institute in Puertollano, South of Spain) serves as a connecting thread. A second series will follow, focusing on interviews with industry representatives.

Register for updates on concentration photovoltaics

Power supply systems and power industry in contemporary world are significant, if not the most important, sectors of any company, each country and the entire world economy.

The continuity of power delivery is of fundamental importance for all customers, particularly for the industry and public sector.That's why the issue of on-line monitoring and measuring of power consumption, electric power consumption, and selected power quality parameters becomes more and more important. The information and characteristics contained in this paper depict the capabilities of intelligent building systems.

The presented applications of intelligent building systems have an opportunity of significant development particularly with prospects connecting them with local networks in buildings or industrial facilities (Ethernet network) and global Internet web. That way the data on building power supply can be remotely analyzed, practically throughout the world.

The implementation of capacitor reactive power compensation in the Lubin Mine has produced the expected technical and economic effects. One should, however, be aware that compensation could be applied only to the level determined by reactive power demand. Currently this level in the Lubin Mine is 11‑12 MVAr. In case of a significant increase of the concentration of output in the distant areas of the mine, other technical measures will be necessary. The objective of a currently undertaken study is to develop a technically and economically feasible method for power supply of distant production sections, which consists in their electrical separation. All concept studies of the power supply system development should also take into consideration rational management of reactive power in both the supply networks and the loads. The rational management of reactive power should be based upon a continuous monitoring of load and reactive power flow.

By Bora Alboyaci and Bahtiyar Dursun

The aim of this paper is to review the connection requirements of wind farms to the grid and how grid codes must be adapted in order to integrate wind power generation capacity without affecting the quality and stability of the electricity system. This paper also summarizes the grid codes that have already been modified to incorporate high levels of wind power. Grid connection requirements in selected countries such as Denmark, Germany, Netherlands and Turkey are investigated in detail.

By F Ferrandis et al

While modern industrial facilities are enjoying huge benefits from the evolution of power electronic devices in terms of productivity, quality or cost-reduction, their high sensitivity and little ride-through capability to common power quality disturbances result in significant economic losses. Nowadays it is possible to reach almost 100% availability of power supply with both DC and AC for many applications. However there is still a gap when facing to apply some of these power quality solutions in high power industrial processes, for several reasons (investment, space, long-term energy losses cost, high temperatures or dirtiness, regenerative loads), since most of them were developed for IT industries. When immunizing against disturbances, purchasing cost, return on investment versus saving, maintenance cost, efficiency, size, reliability or availability are the key decision criteria to industrial decision makers.

Driven from the real need of industrial customers to solve power quality problems and having in mind these criteria, IBERDROLA in collaboration with CORPORACION ZIGOR has developed two families of power conditioning solutions specifically designed for industrial end-users and created to cover almost any kind of power quality issues.

These solutions have been validated in a variety of industrial facilities including ceramic tiles manufacturing, plastics and polymers processing, paper manufacturing or pumping stations.

By M Bollen et al

This paper presents the status of the work in C4.110, a joint working group by CIGRE, CIRED and UIE. The scope of the working group is to gather technical knowledge on the immunity of equipment, installations and processes against voltage dips, and to use this knowledge in the further development of methods and standards. The activities of the working group are divided in seven “chapters”, where the work has started in three chapters: “equipment and process performance”, “voltage dip characteristics” and “economics and probabilities”.

By Stefan Fassbinder

The German Federal Minister for the Environment would like to ban the use of incandescent tungsten-filament light bulbs. For instance, one of the issues raised is that of dimming. As most of the dimmers installed are used to control incandescent bulbs, it’s worth taking a closer look at the issues involved.

Angelo Baggini, Franco Bua, Francesco Buratti

This paper summarises the outcomes of a European survey, aiming to evaluate typical office building electrical installation design practices in the years 2000 and 2005 in terms of adoption of Power Quality solutions.

A global installation model was built on a feeding model obtained by national market researchers on office buildings based on the Delphi approach. Interview results have been processed in order to define adoption frequencies of design issues solution covering the whole building electrical design.

The outcome of the survey showed a design practice modification in the examined period, which can be summarised as an increase in: reserve and emergency supply adoption, double radial scheme adoption, derating factor adoption for transformers, reactors and motors, high efficiency motors usage, neutral conductor oversizing, power monitoring equipments installation, plugs number and a TRMS approach for cable sizing.

Born from the experience of Leonardo's award winning LPQI project, on April 11th, the new Handbook of Power Quality will be available worldwide, published by Wiley.

The book uses the perspectives of both power suppliers and electricity users, with contributions from experts in all aspects of PQ providing a balance of scientific and practical information on:

• Frequency variations

• The characteristics of voltage, including dips, fluctuations and flicker

• The continuity and reliability of electricity supply, its structure, appliances and equipment

• The relationship of PQ with power systems, distributed generation, and the electricity market

• The monitoring and cost of poor PQ

• Rational use of energy