Partial Discharge in Electronic Equipments

Tato disertační práce se věnuje studiu částečných výbojů (PD) způsobených poklesem spolehlivosti a životnosti elektronických zařízení a systémů. Diagnostika PD je dnes známá metoda pro vysoké napětí u vysoko-výkonných zařízení. V případě elektronických zařízení PD testování není ale běžně používáná metoda, přestože je zde také potenciál pro vysoké elektrické zatížení vzhledem k velmi krátké vzdálenosti. Tato práce je zaměřena na vyšetřování PD činnosti u elektronických zařízení. Bylo navrženo a provedeno pracoviště pro diagnostiku PD v elektronických zařízeních. Pracovní frekvence se pohybuje od několika stovek Hz až 100 kHz. Maximální amplituda PD testovaného napětí je vyšší než 10 kV. Navzdory jednoduché konstrukci toto zařízení přináší vysokou spolehlivost měření. Více než 300 PD testů bylo provedeno na různých elektronických zařízeních a elektronických součástí,např. na planárních transformátorech a elektronických komponentách používaných při vysoko-napěťových měničíchThis dissertation thesis is devoted to study of partial discharge (PD) caused decrease of reliability and lifetime of electronic equipments and systems. PD diagnostic is nowadays well known method for high voltage high power equipments but in case of electronic devices PD testing it is not used routinely despite that there is also a potential for high electric load due to extremely short distances. The risk of PD caused failure is here extremely high because of high working frequency and consequently high repetition rate of PD events. Therefore, this work is focused on investigation of PD activity in electronic equipments. The workplace for PD diagnostic in electronic devices based on switched power supply was designed and made. Working frequency ranges from several hundreds of Hertz up to 100 kHz. The maximal amplitude of PD testing voltage is higher than 10 kV. Despite the simple design this equipment brings high repeatability and reliability of measurement. More than 300 PD tests were made on different electronic devices and electronic components, on planar transformers, and on components for voltage gate drivers for use in high voltage power converters. Possibilities of PD tools in investigation and engineering ofd insulation systems were demonstrated.

Emerging technologies and future trends in substation automation systems for the protection, monitoring and control of electrical substations

Tese de Mestrado Integrado. Engenharia Electrotécnica e de Computadores (Automação). Faculdade de Engenharia. Universidade do Porto. 201

A General Easy-to-use Expression for Uncertainty Evaluation in Residual Voltage Measurement

The paper addresses one of the new and most important issues arising when Low Power Voltage Transformers (LPVTs) are used in power network substations for evaluating, among others, the residual voltage measurement. Conversely to open-triangle inductive instrument transformers, the use of phase voltage transformers for measuring the residual voltage gets challenging due to the very high accuracy required for the three LPVTs. In the paper, a general expression to estimate the residual voltage measurement uncertainty, starting from the LPVTs accuracy, is presented. The effectiveness of the proposed approach is then confirmed with both Monte Carlo simulations and actual measurements on a general three-phase system

Experimental electronic instrument for a hydraulic towing winch

Peer Reviewe

An Investigation into the testing and commissioning requirements of IEC 61850 Station Bus Substations

The emergence of the new IEC 61850 standard generates a potential to deliver a safe, reliable and effective cost reduction in the way substations are designed and constructed. The IEC 61850 Station Bus systems architecture for a substation protection and automation system is based on a horizontal communication concept replicating what conventional copper wiring performed between Intelligent Electronic Devices (IED’s). The protection and control signals that are traditionally sent and received across a network of copper cables within the substation are now communicated over Ethernet based Local Area Networks (LAN) utilising Generic Object Oriented Substation Event (GOOSE) messages. Implementing a station bus system generates a substantial change to existing design and construction practices. With this significant change, it is critical to develop a methodology for testing and commissioning of protection systems using GOOSE messaging. Analysing current design standards and philosophies established a connection between current conventional practices and future practices using GOOSE messaging at a station bus level. A potential design of the GOOSE messaging protection functions was implemented using the new technology hardware and software. Identification of potential deviations from the design intent, examination of their possible causes and assessment of their consequences was achieved using a Hazard and Operability study (HAZOP). This assessment identified the parts of the intended design that required validating or verifying through the testing and commissioning process. The introduction of a test coverage matrix was developed to identify and optimise the relevant elements, settings, parameters, functions, systems and characteristics that will require validating or verifying through inspection, testing, measurement or simulations during the testing and commissioning process. Research conducted identified hardware and software that would be utilised to validate or verify the IEC 61850 system through inspection, testing, measurement or simulations. The Hazard and Operability study (HAZOP) has been identified as an effective, structured and systematic analysing process that will help identify what hardware, configurations, and functions that require testing and commissioning prior to placing a substation using IEC 61850 Station bus GOOSE messaging into service. This process enables power utilities to understand new challenges and develop testing and commissioning philosophies and quality assurance processes, while providing confidence that the IEC 61850 system will operate in a reliable, effective and secure manner

Mapping and Testing Internet of Things Platforms for the Intelligent Maintenance of the Electrical Distribution Network

New technologies are crucial in the changing energy sector and the electricity network. The climate change and increasing dependence upon electricity are two main factors in this con-text. Consequently, there is a need to develop the reliability and quality of the electricity distribution system. The study was carried out in cooperation with Vaasan Sähköverkko. They wanted to explore and pilot possible alternatives to internet of things (IoT) technologies to be used in predictive maintenance of the electricity distribution network. The purpose of this study was to examine the features expected from good IoT platforms. Central to this study, was to demonstrate that IoT solutions could be built on these platforms in their operating environments connected to the distribution system. Internet of things platforms are a set of integrated software capabilities. The compared platforms in this study were M-Files, IoT-Ticket, Microsoft Azure, Amazon Web Services and Google Cloud Platform. When comparing the selected IoT platforms, data related to different features was collected by implementing four practical cases. The first case was monitoring air conditions at Vaasa primary substation using a Ruuvitag sensor. The second case was use CoreTec and CoreSense to import condition monitoring data from the power transformer at Purola primary substation. The third example was import measurement and status data from the DC system at Alskat primary substation to IoT platforms. In the final case, data was retrieved from MicroSCADA Historian to a comma separated value file and exported to IoT platforms using either the representational state transfer application programmable Interface (REST API) or a Python software development kit. The results of this study demonstrate that it is possible to install of IoT technology on significantly different platforms. M-Files was the IoT platform with largest amount of open questions still remaining. IoT-Ticket appeared to be the easiest option for installation and end use. If an organization were to choose Microsoft Azure, Amazon Web Services or Google Cloud Platform, they would need to find reliable partners to develop the platforms with end users. During this study, it became evident that IoT technology is relatively evolved and organizations should begin using to use it with a low threshold if suitable applications are found. For example, predictive maintenance can be considered as a particularly suitable option for the IoT platform further utilization by a distribution system operator

Adaptive overcurrent protection application for a micro-grid system in South Africa

Abstract: The non-directional overcurrent protection (International Electrotechnical Commission standard IEC 617 or American National Standards Institute ANSI/Institute of Electrical and Electronic Engineers IEEE C37.2 standard device number 51) is one protection type/relay function that has stood the test of time. The latest generation of relays has brought about enhanced capabilities. The most popular overcurrent protection, which is the Inverse Definite Minimum Time (IDMT) function, has proven to provide coordination of electrical nodes with ease. This is one of the oldest but extremely reliable relay characteristic. A number of new protection functions and enhancements to existing functions are commensurate to the advanced technical capabilities of the newer generation protective devices. The new development techniques include “acceleration”, which is a technique of sending the circuit breaker status of the near end of a line or feeder to the far end to influence the relay decision at the far end. Impedance protection, unit line protection, etc. have come with many advanced characteristics and properties. The enhancements to protection devices bear special features but cannot substitute inverse time overcurrent protection, which, up to now, is a reliable backup in feeder protection schemes in South Africa. The superior feature is the capability to achieve coordination between a series of protective devices. This is achievable without excessive damage to the electrical components of the circuit...M.Ing. (Electrical Engineering

Condition Based Monitoring For Protection System

The objective of this project is to implement Condition Based Monitoring into Power System Protection. This project is focusing on the distribution level protection system with 11kV voltage rating

Microprocessor protection relays: new prospects or new problems?

The internal architecture and principles of operation of microprocessor-based devices including so-called "microprocessor protective relays" have little in common with devices called "electric relays". But microprocessor-based relay protection devices are gradually driving out the traditional electromechanical and even electronic relay protection of virtually from all fields of power and electrical engineering. Advantages of microprocessor-based protection means over traditional ones are far from being absolute or obvious, yet this is a general trend. In reality, however, microprocessorbased protection means have several specific 12 drawbacks too. In this paper, some of these problems are discusse