Power Quality

By J A Rosendo et al

This paper presents a software tool, named INCA, for the assessment and improvement of supply reliability indices. Based on statistical failure rates associated to each individual component, and other recorded information, such as restoration and reparation times, INCA obtains expected reliability indices related with the number and duration of interruptions, for a feeder or set of feeders. INCA then allows the user to improve the resulting indices so that they are within permisible limits. This is carried out, either automatically or assisted by the user, by means of systematic procedures such as the addition of protecting devices or the modification of the feeder topology.

By E Mascarell

European utilities have a great impact on liberalization, globalization, regulations and environmental issues. Technology and Innovation has become the key drive to offer added value to its final clients and its strategic advantage over competitors. ENDESA has developed an Innovation Plan called “Micro Plan” in order to accelerate the innovative transformation of the company and its infrastructures to the present and the future of technologies.

“MICRO PLAN” considers and analyzes the whole Endesa’s electrical Distribution Substations System. Endesa has developed a hierarchical tree in which every component is analyzed and all the possible failures are considered. There is a complete list of the parts of a substation, its functionality and the expected way every part could fail. Decisions will be taken after all the analysis is done and present and future technologies become a real part of Endesa’s system.

Endesa is going to enhance a traditional maintenance model based on corrective and preventive tasks, into predictive models where the key word is “reliability”. The aim is to consider what are the critical tasks and its periodicity to achieve the best performance of the equipments. This conditioned-pair has to be optimized, not only by introducing the effective tasks but also by considering the optimal planning that has to be implemented. Nor too early, when it is not necessary to execute any maintenance task, neither too late, when the problem has no solution or the equipment is hardly committed. A multitudinary task force has been created with the most relevant experts in the company: O&M teams, network planning, external suppliers, and R&D organizations, where the objective is the most immediate future maintenance.

The current article explains the RCM methodology, the root- cause analysis and its development planning. This innovation model is based on the knowledge and expertise of technicians with a clear management commitment in the electrical utility environment considering the sector trends.

By V Detrich et al

This paper deals with the utilization of the costs of penalty payments when making decisions of the distribution company on measures to be undertaken in the network. The costs of penalty payments are derived from breaching the customer’s standard of the electricity supply continuity for individual consumers. A composed customer’s standard with a limit of the annual number of supply interruptions and a limit of the total annual duration of supply interruptions is considered in the paper. The costs of penalty payments are first calculated for the whole 22 kV overhead distribution network depending on a different setting of the limits and then for individual feeders. Although the assessment of the costs of penalty payments for individual feeders enables the reliability of the feeders to be compared, another approach must be used for the evaluation of the contribution of a certain measure undertaken in the network (investments, operational interventions or modification of maintenance). A new method based on the potential of reducing the costs of supply interruptions may represent such an approach. In final part of the paper, the application of this method is demonstrated by the example of using a slow autoreclosing in the overhead distribution network.

Brian Fortenbery from EPRI presents the Industrial Design Guide (IDG). The IDG provides a strong technical basis for working with industrial end users in power quality, distribution, and economic development activities. The tool describes in detail such industrial processes as injection-molded plastics and CNC machining, includes electrical diagrams of the processes and sub-processes, and discusses the economics of process-associated downtime. The descriptions and drawings are interactive, leading the user to important power quality considerations, such as sensitive components, test protocols, solutions, and applications. This authoritative guide to industrial processes can be used to train new power quality engineers, refresh seasoned representatives, and enhance the credibility of all employees in the presence of end users, and the web-based format makes it easy for even novices to use.

This interview is in 2 parts.

By R Gono et al

Monitoring of failures and outages in the transmission and distribution of electrical energy is necessary for determination of the reliability of network components and the supply of electrical energy to consumers. Incorrect input data leads, of course, to false results even if the correct computing method is used. The paper deals with obtaining of reliability indices of distribution network analyzing data about failures and outages of electric power supply from several distribution areas from the Czech Republic and the Slovak Republic. Data sources produce heterogeneous domain data. It is necessary to store them in one common scheme to be able to analyze and query such data. Scheme comes from Distribution Network Grid Code. We proposed multi-dimensional data structure to storage of the data that enable effective querying. Data from particular companies are transformed. The transformation language has been developed for this reason. For evaluation of reliability it is necessary to have data on the number and range of the examined piece of equipment. Thus it is not only the case of data on e.g. the number of failures and the mean duration of a failure of the line of the given type and the given voltage level, but also the case of data on the total range of the observed piece of equipment, i.e. here on the total length of the line of the given type and the given voltage level. The result of analysis is the determination of the failure rate and mean failure duration for particular items of equipment or for group of equipments. With more detailed databases, other pieces of information may be found that are important for operators, such as the most frequent cause of failures, areas of the greatest amounts of undelivered energy, etc.

By D Fita et al

With the integration of Romania into the European Union, the Romanian Power Grid Company TRANSELECTRICA integrated in the year 2004 at the U.C.T.E. through the Electrical Substation 400/220 kV Rosiori (Romania) connected to the Electrical Substation 400/220 kV Mucacevo (Ukraine) and the Electrical Substation 400/220 kV Arad (Romania) connected to the Electrical Substation 400 kV Sandorfalva (Hungary). These Over Head Lines and Electrical Substations were retechnologized in order to synchronies the Western Europe with the Eastern Europe. The retechnologization of the Over Head Lines and Electrical Substation had the goal of improving the quality of the electrical power transported according to the U.C.T.E. standards.

Energy costs are an increasingly significant burden for the Chemicals sector. Whilst the pricing of already high costs for oil, natural gas, and electricity are out of the sector’s control, the cost of energy does not stop at signing the annual energy contract. Many chemical plants incur significant financial losses due to electrical power systems that cannot cope with commonly experienced irregularities in the power supply. In some cases, these unplanned losses represent the difference between making a profit or making a loss. The European Copper Institute’s Power Quality (PQ) Survey questioned whether the sector’s own electrical power systems are adequately designed to withstand such common power interruptions and disturbances.

By D Sarussi et al

Emergency & Standby Power Systems (E&SPS) are integral parts of safety systems. E&SPS is used as a safety system that support features for the purpose of supplying and distributing power to the safety systems and to other designated items important to safety. In this paper we will present a modern approach in designing a reliable static and dynamic combined, uninterrupted emergency power system. We will also show an implementation using statistical method of system reliability testing plan, according to the IEC 60605 standards.

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 C Pica et al

Power conditioners for low-voltage DC sources in Distributed Generation usually have two major functions: to boost the energy source output voltage and to convert it into an AC voltage. The voltage boost is usually done by a DC-DC converter. This paper shows alternative topologies for standard DC-DC converters, in which the converter is series-connected with the source. The convenience of series-connected converters is evaluated by means of analytical results. Then, two standard DCDC converters have been “re-designed” in series-connected versions and their operation has been evaluated in simulation: the switches peak current can be significantly reduced, thus reducing the costs and improving the energy source utilization.

By P Parthasaradhy et al

75%of the electrical energy generated is utilized for running industrial and domestic motors. The manufacturers and consumers of these motors are now keen to include condition-monitoring equipment, which improves the safety and reliability of the equipment. Early detection of abnormalities in the motors will help to avoid expensive faults. In this paper, we consider a 400V, 50Hz squirrel cage Induction motor and estimate the Rotor resistance, inductance, stator current, rotor flux (along both, direct and quadrature axis) by means of extendable kalman filter, which takes into account measurement and modeling inaccuracies. Vas model of Induction motor deduced from the park transform is used for simulation and the Rotor inductance, resistances are considered as parameters as well as states. It has been observed that the parameter estimates (estimated values of stator currents, rotor flux, rotor résistance, inductance) converges to the true values with a reasonable degree of accuracy. The method for analyzing internal faults based upon the estimated data is explained in the paper. Thus continuous monitoring of machine parameters by the above method can be very useful in detecting different internal faults occurring in Induction motor.

By R Langella et al

Analyses to have a quantitative idea of the real behavior of Switching Power Supply (SPS) units from the point of view of waveform distortion and power absorption are developed. Results of several experimental tests performed by means of a test system built up at Laboratories of the Second University of Naples (Italy) are firstly reported. Then, suitable models are proposed to easily predict the behavior of SPS sets supplied by the same busbar when their number varies and these models are validated by means of accurate time domain simulations. Experimental and numerical results are discussed.

Power Quality monitoring has become a standard task in electrical network management. Amir Broshi explains how he noticed through "real life" case studies of Power Quality troubleshooting that solving the Power Quality problem with measurements simply taken to comply with standards is sometimes not possible. He shows that by providing engineers with data beyond the standards, an unprecedented number of Power Quality events can not only be captured, but are definitively solved.

Power Quality cost analysis is always subject to different vision within the same site or company. Amir Broshi explains why such a difference in point of views exists and how they are linked to one's partial vision of a global problem. In conclusion, he offers a tool: a simple checklist to give a complete overview of poor power quality costs impacts for electricity professionals as well as the decision makers, financial and site managers.

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.

There is still a gap when attempting 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 immunising 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.

In order to clearly identify responsibilities for voltage quality disturbances on the point of connection (POC), voltage and current requirements have to be available at the POC. So, the relationship between inrush currents, flicker severity levels and grid impedances in the low voltage grid should be explained.

Furthermore, maximum harmonic currents at the POC in low voltage grids are determined by using these grid impedances.

J Cobben explains how he and his team developed a very simple ABCDEF classification to help everybody by having a common tool with which to assess power quality requirements.

Bart Franken & Erwin Hoeskma from Kema explain what regulators need to consider in establishing an effective voltage quality regulatory framework for distribution networks. In particular, they consider the regulation of five voltage quality dimensions: short interruptions, voltage dips, flicker, supply voltage variation, and harmonic distortions. Their work assesses the most appropriate regulatory control method and presents practical experiences through a number of case studies.