SPURIOUS ACTIVATION ASSESSMENT OF THERMAL POWER PLANT’S SAFETY-INSTRUMENTED SYSTEMS

Safety-instrumented systems (also called technological protections) play the significant role in prevention and mitigating of major accidents that can occur on thermal power plant. Activations of safety-instrumented system turn the power unit into safe state by shutting it down or reducing it productivity. The power generation process operates continuously. Any unplanned outage of generation equipment leads to undersupply of energy and big commercial losses to generation company. In Russia the values of allowed spurious trip rate for safety-instrumented systems are set by regulatory agency. These values are strict to all technological protections and do not take into account the differences in amounts of losses. This paper presents more flexible approach based on the Farmer’s risk criterion. Also risk reduction factor for spurious activation is proposed

Performance Assessment of TSO–DSO using Volt-Var Control at Smart-Inverters

The massive penetration of distributed energy resources (DERs) in distribution networks provides a strategic opportunity for the distribution system operator (DSO) to coordinate the assets appropriately and offer services to the transmission systems. The IEEE std. 1547-2018 introduced a control mechanism to enable the power electronic converters (PECs) to offer several services, including voltage regulation by controlling the reactive power injection/absorption; this type of PECs is also known as "smart inverter". The participation of the smart-inverters in the voltage regulation with a novel customer-centred piece of legislation and markets provide the DSO with powerful tools to enforce very positive TSO/DSO interactions. This research paper presents a comprehensive assessment of the steady-state performance provided by voltage control at the smart-inverters to the TSO – DSO system. The assessment includes analysing main indicators using time series considering short term (24-hours, 1-minute resolution) and long-term (one-year) horizon. In this paper, the three leading indicators are used as criteria for the assessment: total energy losses voltage profile in the TSO-DSO system and the power flow interaction at the interface between the systems. The assessment is based on numerical results using the DIgSILENT PowerFactory simulation tool, where the voltage controllers have been implemented, and regional electrical system in south-eastern Norway, the area of Vestfold and Telemark as been used for illustrative purpose

The use of DigSilent Power Factory Simulator for "Introduction into Power Systems" Lectures

The first-year students at the technical universities often face with the problem of school knowledge usage at a higher level, required by engineering. To solve this problem, the authors developed lectures, based on simulations in DigSILENT Power Factory software with theoretical background. On the example of the simple models, in the lectures, the value of physical quantities is explained, as well as the purpose and characteristics of the power equipment.This article includes the detailed description of a lesson “Introduction into power systems” and presents some models and ways of explaining the material. The sections below concentrate on the format of the lecture, methods for explanation of physical quantities, and acquaintance with the power system components. Sequential parts create the mosaics of grid, with the following description of basic laws and principles in power systems

The Use of DigSilent Power Factory Simulator for “Introduction into Power Systems” Lectures

The first-year students at the technical universities often face the problem of using the previously acquired knowledge at a higher level required by engineering education. To solve this problem, the authors developed a series of lectures dedicated to establishing theoretical background, based on simulations in DigSILENT Power Factory software. In the lectures, the physical values and quantities as well as the purpose and characteristics of the power equipment are explained on the example of the simple models

Gold in Mineralized Volcanic Systems from the Lesser Khingan Range (Russian Far East): Textural Types, Composition and Possible Origins

While gold partitioning into hydrothermal fluids responsible for the formation of porphyry and epithermal deposits is currently well understood, its behavior during the differentiation of metal-rich silicate melts is still subject of an intense scientific debate. Typically, gold is scavenged into sulfides during crustal fractionation of sulfur-rich mafic to intermediate magmas and development of native forms and alloys of this important precious metal in igneous rocks and associated ores are still poorly documented. We present new data on gold (Cu-Ag-Au, Ni-Cu-Zn-Ag-Au, Ti-Cu-Ag-Au, Ag-Au) alloys from iron oxide deposits in the Lesser Khingan Range (LKR) of the Russian Far East. Gold alloy particles are from 10 to 100 µm in size and irregular to spherical in shape. Gold spherules were formed through silicate-metal liquid immiscibility and then injected into fissures surrounding the ascending melt column, or emplaced through a volcanic eruption. Presence of globular (occasionally with meniscus-like textures) Cu-O micro-inclusions in Cu-Ag-Au spherules confirms their crystallization from a metal melt via extremely fast cooling. Irregularly shaped Cu-Ag-Au particles were formed through hydrothermal alteration of gold-bearing volcanic rocks and ores. Association of primarily liquid Cu-Ag-Au spherules with iron-oxide mineralization in the LKR indicates possible involvement of silicate-metallic immiscibility and explosive volcanism in the formation of the Andean-type iron oxide gold-copper (IOCG) and related copper-gold porphyry deposits in the deeper parts of sub-volcanic epithermal systems. Thus, formation of gold alloys in deep roots of arc volcanoes may serve as a precursor and an exploration guide for high-grade epithermal gold mineralization at shallow structural levels of hydrothermal-volcanic environments in subduction zones

Analysis of Traditional and Alternative Methods for Solving Voltage Problems in Low Voltage Grids: An Estonian Case Study

Smart Cities can benefit from existing municipal low voltage (LV) distribution grids by supporting public services with permanent power supply and providing grid connection points to distributed generators (DG). The increased integration of DGs and inverter based non-linear loads increases voltage quality issues, thus the cost-efficient assurance of voltage quality in LV grids with long radial lines is of increasing importance for the operators of municipal electricity distribution systems. Conventional methods for mitigating voltage quality issues (e.g., power line renovation) might not be optimal solutions either technologically or economically. Existing studies do not address all relevant issues related to the assurance of required voltage quality in such LV grids. This paper provides an overview of the applicability and rationality of traditional as well as alternative methods to solve voltage problems in LV grids. The authors use DIgSILENT PowerFactory software to simulate the performance of voltage stabilisers under different conditions. The authors propose a robust method for the classification of LV feeders and provide recommendations on how to resolve voltage quality problems, with the help of different power quality improvement devices, where the traditional methods of upgrading to medium voltage and grid reinforcement are economically infeasible. Based on our results, recommendations for mitigating voltage quality problems in LV distribution grids with radial lines of different lengths are given

Analysis of Traditional and Alternative Methods for Solving Voltage Problems in Low Voltage Grids: An Estonian Case Study

Smart Cities can benefit from existing municipal low voltage (LV) distribution grids by supporting public services with permanent power supply and providing grid connection points to distributed generators (DG). The increased integration of DGs and inverter based non-linear loads increases voltage quality issues, thus the cost-efficient assurance of voltage quality in LV grids with long radial lines is of increasing importance for the operators of municipal electricity distribution systems. Conventional methods for mitigating voltage quality issues (e.g., power line renovation) might not be optimal solutions either technologically or economically. Existing studies do not address all relevant issues related to the assurance of required voltage quality in such LV grids. This paper provides an overview of the applicability and rationality of traditional as well as alternative methods to solve voltage problems in LV grids. The authors use DIgSILENT PowerFactory software to simulate the performance of voltage stabilisers under different conditions. The authors propose a robust method for the classification of LV feeders and provide recommendations on how to resolve voltage quality problems, with the help of different power quality improvement devices, where the traditional methods of upgrading to medium voltage and grid reinforcement are economically infeasible. Based on our results, recommendations for mitigating voltage quality problems in LV distribution grids with radial lines of different lengths are given