M5

Power Quality Training Courses

Reliability of electricity supply

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Module 5 Reliability of electricity supply

1 INTRODUCTION The aim of this module is to provide the user a detailed overview of the reliability of electricity supply problems, by supplying a guidance for the choice of the scheme for the electrical grids and of the emergency and standby power systems, by giving the users a comprehensive description of static and rotating UPS features. In the last sections of this module users can find additional informations about the new emerging technologies as well as some good engineering practices. 1.1 General aims This module’s general aim is to provide the attendants the basic knowledge about the concept of reliability, and some tools for the choice of the scheme and features of power systems and to evaluate the reliability of the choosen system. The aim is achieved through 8 didactic sections, as follows: − Section 1: Definitions and Standards; − Section 2: Mathematical methods to evaluate reliability; − Section 3: Basic schemes of electrical grids; choice of the schemes; − Section 4: Emergency and standby power systems; − Section 5: Static and rotating UPS systems; − Section 6: Emerging Technologies; − Section 7: Good engineering practices; − Section 8: Case study. 1.2 Target groups This module’s target group includes: designers, experts, installers, users, grid operators, and all those who wish to expand their knowledge in reliability of supply. 2 SPECIFIC AIMS AND TOPICS The pathway of learning consists of a 2 days course, subdivided in sections (with different duration), with these contents and related aims.

Contents

Aims

Contents Aims

1st day Definitions (reliability, redundancy, etc…); mathematical methods to evaluate reliability; basic schemes of electrical grids (simple radial system, ring scheme, etc…); rules for the choice of the schemes. The aim of the first day lessons is to introduce the basic knowledge related to reliability of supply. After an introductory section with all the related definitions, the successive lessons provide the users some tools for a correct choice of the power supply scheme. 2nd day Emergency and standby power systems; static and rotating UPS systems; emerging Technologies; good engineering practices; case study. The second day lessons aim is to provide the attendants some practical informations and tools on the the choice of the emergency and standby power systems. The last sections of the course will be dedicated to UPS’s and new emerging technologies.

Below there’s a detailed overview of the course contents. www.lpqi.org

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2.1

Pathway of learning flow chart

Time progression (hours)

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COURSE DETAILED PROGRAM

General notes: − each day there will be one coffee break (30 mins) which will divide the lesson in two parts no longer than 2,5 hours; − at the beginning of the course the lecturer will explain course aims and at the end he will verify their fulfilment through a knowledge test; − the course will be divided in theoretical and practical sections;

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−

at the end of the lessons, a user satisfaction survey will help the lecturer in monitoring the course quality.

First day: 30 mins

Participants registration and course introduction

30 mins

Section 1: Definitions − Availability and continuity − Reliability (see IEC IEV ref. 191-12-01) − Redundancy Modality: Lesson

60 mins

Section 2: Mathematical methods to evaluate reliability Modality: Lesson

60 mins

Section 3: Basic schemes of electrical grids − Simple radial system − Ring scheme − Double radial scheme − Meshed scheme − Compound scheme Modality: Lesson

30 mins

Coffe break

90 mins

Choice of the schemes − Parameters and basic conditions − Scheme of the grid as a link between supplies and loads − Characteristics of the installation − Independence − Bottlenecks − Uniform availability and limit of tight of the components − Redundancy of protections − Resilience and flexilility – capability of replacement − Reserve power − The system supply section and end section − The functions “standard” and “preferential” Modality: Lesson and discussion

Second day 60 mins

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Section 4: Emergency and standby power systems − Descriptions and applications of available systems − Basics − Engine-Driven Generators − Turbine-Driven Generators − Mechanical-Stored Energy System − Inverter/battery Systems − Introduction Uninterruptible Power Systems Modality: Lesson

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60 mins

Section 5: Static and rotating UPS systems − General description of the technology − Main Characteristics and limitations − Applications − UPS Structures − Energy storage (battery) − Standards Modality: Lesson and discussion

30 mins

Coffe break

30 mins

Section 6: Emerging Technologies − Fuel cells − Supercapacitors − Superconductors Modality: Lesson and discussion

60 mins

Section 7: Good engineering practices − STS − Grounding − Protection − Maintenance Modality: Lesson and practical training

30 mins

Section 8: Case study Modality: Lesson and practical training

60 mins

Final discussion; end of the course; user’s satisfaction questionnaire; Confirmations of attendance

4 TEACHING METHODS Teaching methods are summarized in three main moments: − knowledge transfer (Lesson) topics exposure by the lecturer with the help of slides and eventually other electronic tools (animations, data sheets, didactic movies…); − deepening/learning verification (Discussion) general discussion stimulated by the lecturer (also during the lesson) to verify knowledge transfer and to eventually deepen particular topics; − practical training (and eventually laboratory activities) group work (~ 6 persons/group) for topics deepening, practical problems solution and case studies overview under the supervision of the lecturer. During all the sections, the lecturer will always attend, with teaching and/or activity coordination duty. 5 DIDACTIC MATERIAL AND TOOLS The didactic tools which will be used by the lecturers will be: − Blackboard − Video-projector − Notebook − Microphone The lecture room will be suitable to allow the use of all the above listed didactic tools and to enable group work for the attendants. www.lpqi.org

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Each user will receive, during the registration, a folder containing: − course program; − lecture notes containing all or part of the lecture slides; − LPQIVES knowledge database access personal key. All this didactic material, and eventually some additional electronic tools, will be available also in electronic format at: http://lpqi.org/custom/1036/ The folder will also include a user satisfaction questionnaire and a knowledge test (which will be both filled and submitted at the end of the course). 6 EXISTING KNOWLEDGE REQUIREMENTS The user’s existing knowledge should include: Topic

Basic

Mathematical analysis Statistic Electrical circuits Power systems Power quality

Level Medium • •

High

• • •

7 ACQUIRED COURSE KNOWLEDGE REQUIREMENTS At the end of this course the user will have learned the basic aspects related to the key concept of reliability along with some practical informations and tools on the choice of the scheme to adopt for power supply and on the choice of the emergency and stand-by supply.

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ANNEXES - MIDAS REPORT

Press PR-00017, Gellerson, M, Munasinghe, M, Economic criteria for optimising power system reliability levels, Bell Journal of Economics, Vol 10, issue 1 The standards of reliability of electricity supply have previously been determined on a rule-of-thumb basis. This paper presents a generalized simulation model for optimizing the reliability level by comparing the social benefits and costs of changes in power system reliability. The supply side costs of increasing system reliability can be determined from straightforward engineering considerations. On the demand side, the benefits to electricity users consist of cost savings from averted power failures or outages which may be measured by the disruption of the output streams owing to idle input factors and spoilage. The theory is applied to the case study of Cascavel, Brazil to determine a range of optimum reliability levels for long-range electric power distribution system planning. The principal outage costs are incurred by industrial and residential consumers.

PR-00013, Pierce, L, Transformer Design and Application Considerations for Nonsinusoidal Load Currents, IEEE Transactions on Industry Applications, 01/06/1996 Transformer design and application considerations for nonsinusoidal load currents

PR-00014, Yin, W, Failure mechanism of winding insulations in inverter-fed motors, IEEE Electrical Insulation Magazine, Nov/Dec 1998 The failure of magnet wires under repetitive pulses as seen in inverter-fed motors cannot be attributed to a single factor but is a result of the combined effects of partial discharge, dielectric heating, and space charge formation. Voltage overshoots produced by PWM drives may be above discharge inception voltage. Partial discharge may therefore be present in inverter-fed motors. In addition to partial discharge, pulses with a fast rise time and high frequency enable the insulation to generate local dielectric heating, which increases the local temperature. The degradation rate of the insulation is

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therefore increased. Furthermore, the fast rise and fall of pulses make it possible for space charges to accumulate in the winding insulation and on its surface

PR-00010, Gellings, C, Electric Infrastructure to power a digital society, IEEE Power Engineering Review, Jan 2002 EPRI initiated an ambitious program designed to ensure that high-quality digital-grade electric power can be delivered reliably to meet the needs of a digital society.

PR-00019, Dugan, R, McDermott, T E, PQ, reliability and DG, IEEE Electrical Insulation Magazine The distributed generation (DG) owner's reliability, measured by the sustained interruption indices, should improve markedly if DG has been installed and operated properly. However, because this is just one customer out of hundreds or thousands on the feeder, the improvement does not show up the utility's traditional reliability indices. There can be a positive or negative impact on the utility-level indices in these cases: DG can reduce the number or the duration of sustained interruptions if automated switches are available to restore power in DG-supplied islands or to DG-supported alternate feeds; the loss of fuse-saving on laterals can significantly degrade the utility-level indices. There is little opportunity for DG to affect the PQ of other customers, as measured by the indices for voltage sags, which are related to faults and interruptions. DG can still have adverse impacts on harmonics and steady-state voltage regulation, which are other aspects of PQ. Utilities should consider tracking ASIFI, ASIDI, and other indices that are based on load size rather than the number of customers. As a supplement to the traditional reliability indices, these would better show the positive impacts of DG, assuming DG owners tend to be larger customers.

PR-00022, Eaton, D, Hammond, P, Rama, J, Neutral shift, IEEE Industry Applications, NovDec/2003 Five years of continuous operation with adjustable speed drives. Case study of a compressor drive in a refinery.

PR-00024, Tschaetsch, H-U, Kopplung zweier MS-Netze in Ulm optimiert Leistungsbedarf, ETZ, 5/2004 Two networks of regional utilities located in Ulm (Baden-Württemberg) and Neu-Ulm (Bavaria) on either side of the Danube river were coupled via a MV DC-link to enable an interchange of electrical energy. The reason for linking two synchronous networks via an inverter instead of a variable transformer or something like that was that both active and reactive power flow had to be controlled independently, and because the inverter acts as a very fast electronic switch separating the two grids in case of short circuit on one side. So the short circuit current carrying capabilities on either side could remain as they were.

Publication REP-00147, 2000, Understanding power quality problems - Voltage sags and interruptions: 2. Long interruptions and reliability evaluation, Book Chapter 2 of the book "Understanding power quality problems - Voltage sags and interruptions" (IEEE Press, ISBN 0-7803-4713-7) Observation of system performance Standards and regulations Overview of reliability evaluation Basic reliability evaluation techniques Costs of interruptions Comparison of observation and reliability evaluation Example calculations

REP-00148, 2000, Understanding power quality problems - Voltage sags and interruptions: 3. Short interruptions, Book Chapter 3 of the book "Understanding power quality problems - Voltage sags and interruptions" (IEEE Press, ISBN 0-7803-4713-7) Terminology Origin of short interruptions Monitoring of short interruptions Influence on equipment Single-phase tripping Stochastic prediction of short interruptions

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REP-00114, 2001, Effect of UPS on system availability (white paper #24), Brochure This note explains how system availability and up-time are affected by AC power outages and provides quantitative data regarding up-time in realworld environments, including the effect of UPS on up time.

REP-00115, 2001, Battery technology for data centers and network rooms: battery options, Brochure The lead-acid battery is the predominant choice for Uninterruptible Power Supply (UPS) energy storage. In 2002, over 10 million UPSs will be installed utilizing Flooded, Valve Regulated Lead Acid (VRLA), and Modular Battery Cartridge ( MBC) systems. This paper discusses the advantages and disadvantages of these three battery technologies.

REP-00124, 2002, Distributed generation impact on reliability and power quality indices, Paper Properly sited distributed generation (DG) can increase the feeder capacity limit, but this does not necessarily produce an improvement in system reliability or power quality, as quantified by standard indices. The DG may have a positive impact on reliability through faster system restoration following a fault. The DG can also improve reliability for the owner, and may reduce the severity of voltage sags near the DG. Indices normalized to the number of customers dilute these positive benefits. The DG often has a negative impact on reliability indices through sympathetic tripping, required changes to utility overcurrent device settings, and increased fuse blowing. The utility cannot assume DG automatically improves system reliability, and action may be required to ensure that reliability does not actually degrade for other customers

REP-00043, 2002, 4-1 Resilience, Reliability, Redundancy, Application note Three R's concept. MTTF, MTBF

REP-00113, 2002, The different types of UPS systems (white paper #1), Brochure Different types of UPS systems and their characteristics: Each of these UPS types is defined, practical applications of each are discussed, and advantages and disadvantages are listed. With this information, an educated decision can be made as to the appropriate UPS topology for a given need.

REP-00061, 2003, Dependability and LV switchboards - ect 156, Application note Dependability of commercial and industrial low voltage electrical installations. Switchboard functions against failure of the LV distribution system, components, types of power systems.

REP-00062, 2003, Dependability of MV and HV protection devices - ect 175, Application note Methods to meet dependability objectives. Taking dependability into consideration at the design stage, quality control, analysis of gained experience.

REP-00063, 2003, High availability electrical power distribution - ect 148, Application note Design of electrical power distribution systems that provide continuous power supply (UPS, back-up power,...).

REP-00064, 2003, Introduction to dependability design - ect 144, Application note Basic concepts of dependability: reliability, failure rate, maintainability, availability and safety.

REP-00065, 2003, Uninterruptible static power supplies and the protection of persons ect 129, Application note Protection problems related to UPS systems. Suitable solutions for various scenarios.

REP-00092, 2003, Automatic transfering of power supplies in HV and LV networks - ect 161, Application note Various types of transfer schemes, synchronous switching, interrupted circuit transfer, pseudosynchronous switching.

REP-00093, 2003, Electrical installation dependability studies - ect 184, Application note Dependability studies: methodology, tools and examples.

REP-00128, 2003, EMERGENCY SUPPLY DEVICES AND METHODS, Application note The paper serves as a background note to Leonardo Application Guide note no. 4.3.1 about improving reliability with standby power supplies. Compared to Leonardo application note it offers more detailed information about UPS configuration; on line and off line systems and particular application of different UPS's. www.lpqi.org

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REP-00116, 2003, Battery technology for data centers and network rooms: safety codes, Brochure Fire safety regulations and their application to UPS battery installations are reviewed. In some cases, fire codes do not clearly recognize improvements in battery safety resulting from changing battery technology. Valve Regulated Lead Acid (VRLA) batteries are frequently deployed within data centers and network rooms without the need for the elaborate safety systems that are required for Vented (Flooded) Lead Acid batteries. Proper interpretation of the fire codes is essential in the design and implementation of data centers and network rooms.

REP-00119, 2003, A business case for battery-free UPS in industrial applications, Report/study Case study published by Piller. Compares LCC or battery-free and battery-based UPS.

REP-00120, 2003, From redundant sources to dual independent sources, Paper In conventional computer centers, power protection was relatively straight forward, usually based on a centralized UPS. However today's new needs require different UPS and low voltage distribution solutions, including new architectures to maintain a high level of availability throughout all phases of operation and maintenance on complex sites. The article presents the conditions for high availability and a number of solutions that use the latest technology to optimize cost, footprint and availability.

REP-00121, 2003, Switch to high availability, Paper Mission Critical equipment that supports data processing facilities such as telecommunications, banking, Insurance, SAN and internet are sensitive crossover that cannot accept any loss of electrical supply. Moreover the evolution of IT networks lead to a mix of telecommunication and data communication equipment within these facilities. As a result the split of power between AC and DC products within these new buildings is more or less unknown, even after the completion of the building. This is a new trend which requires the power protection providers to think beyond traditional solutions, with the main objective to address simple question from customers: "how to a permanent 24 hour x 365 days available, quality power supply for mixed and evolving mission critical AC and DC equipment at optimum cost?" Taking this into account we propose a method to meet this new demand in terms of architecture and other key factors providing availability, flexibility, scalability, site management and cost effective solutions.

REP-00044, 2003, 4.3.1 Improving Reliability with Standby Power Supplies, Application note Introduction - categories of loads. UPS classification and appliacation.

REP-00122, 2003, Critical Power, Report/study Text on reliability of power supply Content: Demand Powering Public Networks The Vulnerable Public Grid A New Profile for Grid-Outage Risks Powering Critical Nodes Fueling the Digital Economy Hard Power Resilient Power Tiers of Power Adding Logic to the Grid: The Static Transfer Switch Generation and Transmission Distribution and Distributed Generation On-Site Power Stored Energy Backup Generators "Uninterruptible Power" Monitoring, Control, and Reliability-Centered Maintenance Resilient Design Private Investment and the Public Interest Assess Vulnerabilities Establish Critical-Power Standards for Facilities Used to Support Key Government Functions Share Safety- and Performance-Related Information, Best Practices, and Standards Interconnect Public and Private Supervisory Control and DataAcquisition Networks www.lpqi.org

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Secure Automated Control Systems Share Assets Enhance Interfaces Between On-Site Generating Capacity and ThePublic Grid Remove Obstacles

REP-00013, 2003, 4-5-3 Schemes for Power Plants. Simplicity, Reliability, Redundancy, When and Where, Application Note Topology of power despatchning systems; radial, ring, meshed, compoud; features.

REP-00015, 2004, 4-5-6 Resilience. Resilient wiring systems, Application Note Concept and principle of resilience. Resilient wiring systems.

REP-00016, 2004, 4-5-7 Generating sets dimensioning for stand by operation, Application Note Brief on sizing factors, frequency and voltage behaviour

REP-00012, 2004, 4-5-2 Some practical aspects of DC and AC power supplies optimisation, Application Note Different methods to improve power availability: bateries, bateries monitoring and diagnostic systems, transfer switches and their applications

REP-00045, 2004, 4-5-1 Resilient Power Supply in a Modern Office Building, Application note How to design electricity distribution system in an office building.

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