Jako Kilter

Experiences with steady-state PMU compliance testing using standard relay testing equipment

This paper presents the results of steady state compliance testing of phasor measurement units (PMUs) from three different vendors in a laboratory environment. Testing is performed by providing three phase voltage and current injections to the VT and CT inputs of the PMUs through Freja-300 stand-alone protection relay test set. Testing is performed according to the standard “IEEE C37.242-2013 - IEEE Guide for Synchronization, Calibration, Testing, and Installation of Phasor Measurement Units (PMUs) for Power System Protection and Control”. The paper discusses the test setup, testing process and overall test results of this project. The limitations of stand-alone testing equipment and recommendations for utilizing real-time hardware-in-the-loop simulation for thorough testing of PMUs are also presented.

Contemporary and future aspects of cost effective power quality monitoring — Position paper of CIGRE WG C4.112

During the last decade the performance of power quality monitoring equipment has increased, while prices of monitors have continuously decreased. Due this trend network operators have more and more intensified their power quality measurement activities. The number of measured parameters and sites is growing continuously. At the same time these new opportunities cause power quality data management and analysis to become an increasing complex challenge. These new challenges will be addressed by the CIGRE working group C4.112 “Guidelines for Power quality monitoring — measurement locations, processing and presentation of data”, which was established in January 2011. The main intention of its work is the development of a coherent set of guidelines for power quality monitoring in existing and future power networks. Based on a clear identification of different objectives all design aspects for an efficient and cost effective power quality monitoring will be covered by the working group in a holistic way. The paper presents first results of the working group and is especially focused on the cost/benefit aspects of the design process of power quality monitoring systems. After a brief introduction the paper gives an overview of the objectives for power quality monitoring and the different aspects that has to be considered while designing a power quality monitoring system. Next the design aspects of larger monitoring systems are discussed in more detail. Some practical recommendations as well as first ideas of new approaches for future monitoring systems are given.

Harmonic levels of domestic and electrical vehicle loads in residential distribution networks

Purpose of the present paper is to provide the results of the study performed in order to assess current distortion of domestic and electrical vehicle (EV) loads and corresponding voltage distortion in the residential distribution networks. For the study harmonic current amplitudes and phase angles of different home appliances were measured and afterwards the corresponding models were composed in DIgSILENT Power Factory. The focus of the study was to analyse the characteristics of the residential distribution network with and without the EV charging. The results of the study showed an extensive harmonic distortion in residential load current and considerable voltage distortion at the substations busbar. The results presented in this paper are especially important when dispersed generation (DG) and EVs are going to be connected in bulk into the distribution networks.

Residential load harmonics in distribution grid

Purpose of the present paper is to provide the results of the study performed in order to assess current distortion of domestic loads and corresponding voltage distortion in the residential distribution networks. For the study harmonic current amplitudes and phase angles of different home appliances were measured and afterwards the corresponding models were composed in DIgSILENT Power Factory. The focus of the study was to analyse the characteristics of the residential distribution network with different amounts of real nonlinear loads. The results of the study showed an extensive harmonic distortion in residential load current and considerable voltage distortion at the substations busbar. The results presented in this paper are especially important when dispersed generation (DG) and electrical vehicles (EV) are going to be connected in bulk into the distribution networks.

Large scale electric vehicle integration and its impact on the Estonian power system

This paper presents the main aspects of the study about large scale electric vehicle (EV) integration impacts in Estonia. The complex impact of EV charging and the resulting additional load demand on the Estonian power system is discussed. Two different charging principles are analysed - controlled and unmanaged. Standard and quick charging impacts are assessed together with the preheating strategies due to the climatic conditions. The aim of the paper is to model the impacts of EVs on the Estonian power system at sub regional level and to give an input for the Estonian TSO for its network development plans concerning e-mobility integration.

Electricity consumption analysis and power quality monitoring in commercial buildings

The results of the analysis of the electricity consumption and power quality indicators in two office buildings are presented. It comprises electricity consumption and power quality during work days and weekends. The consumption data analysed is from a one year period and the power quality analysis is based on a one week measuring period. The aim of this analysis is to determine the current situation in these buildings in order to study the possibilities and limitations to implement different energy efficiency measures. In addition to the energy efficiency point of view, the problem is also addressed together with the power quality aspects.

Modelling of high-speed electrical railway system for transmission network voltage quality analysis: Rail Baltic case study

During the last few years there has been a wide discussion about different aspects of the connection of highspeed railway, Rail Baltic, into Estonian power system. In order to understand the characteristics of this type of load and its influence to power system operation and power quality a study was made. This paper discusses and presents the results of that study covering the aspects of modelling of the power system, railway network and corresponding load, together with the assessment of determining the influence of different load and network characteristics to the level of power quality in the transmission network. The paper presents a generalized approach to railway network modelling considering the applicability from the perspective of transmission system operator and provides recommendations for network operator in order to guarantee sufficient level of power quality for all network users in case of possible high-speed railway connections.

Using demand side management in energy-intensive industries for providing balancing power - The Estonian case study

This paper represents the preliminary study results of industrial consumers who would be willing to provide demand response services for system balancing. Using aggregated load shifting in a wood industry over the whole Baltic power system for regulation is discussed. The paper covers the main aspects and assumptions used to assess the possible demand response outcomes for the transmission system operator in terms of regulation costs. The aim of the paper is to show that demand response can be deployed and consumers are willing to participate in providing demand response services for the transmission system operator, who should use this information as an input for developing the necessary market entity for balancing services.

Assessment of voltage instrument transformers accuracy for harmonic measurements in transmission systems

The measurement of harmonic and interharmonic voltages up to 2.5 kHz is an inherent part of the Power Quality assessment in electrical networks. In the past the monitoring of harmonic voltages has been of minor importance for many transmission system operators (TSO). As the number of power electronics connected to the transmission grid (e.g. self-commutating HVDC stations or converters in large wind power plants) increases continuously, the concern of TSOs regarding the harmonic levels grows as well. This is also confirmed by the recent significant increase of installed Power Quality monitors in transmission grids. In many cases the traditional voltage instrument transformers (VT), which are only designed to have a high accuracy at rated frequency, are used for voltage harmonic measurements. This questions the accuracy of the harmonic measurements and the reliability of any compliance assessment (e.g. against existing planning levels). The paper illustrates the challenges of harmonic voltage measurements from the viewpoint of the TSO. After a quick description of the initial situation the paper discusses two methodologies to measure the frequency response characteristic of VTs. The methods are applied to 10 VTs of two TSOs and the results are discussed with regard to the suitability of the VTs for voltage harmonic measurements.

Case studies for power quality monitoring in public distribution grids — Some results of working group CIGRE/CIRED C4.112

The implementation of a Power Quality monitoring system can be a complex task. Number of instruments, selection of sites and monitored parameters as well as the final presentation of results strongly depend on the objective of the monitoring. Six major monitoring objectives are identified by the CIGRE/CIRED joint working group C4.112 “Guidelines for Power quality monitoring - measurement locations, processing and presentation of data”: compliance verification, performance assessment, site characterization, troubleshooting, advanced applications and studies and active PQ management. Based on the intensive work and discussion within the working group the paper describes possible implementation processes for selected objectives by particular case studies. For each case the key aspects for a successful and efficient implementation are summarized. The main intention of the paper is to provide some guidelines to network operators with less experience in the field of Power Quality monitoring.