Impact Assessment of Hypothesized Cyberattacks on Interconnected Bulk Power Systems

The first-ever Ukraine cyberattack on power grid has proven its devastation by hacking into their critical cyber assets. With administrative privileges accessing substation networks/local control centers, one intelligent way of coordinated cyberattacks is to execute a series of disruptive switching executions on multiple substations using compromised supervisory control and data acquisition (SCADA) systems. These actions can cause significant impacts to an interconnected power grid. Unlike the previous power blackouts, such high-impact initiating events can aggravate operating conditions, initiating instability that may lead to system-wide cascading failure. A systemic evaluation of "nightmare" scenarios is highly desirable for asset owners to manage and prioritize the maintenance and investment in protecting their cyberinfrastructure. This survey paper is a conceptual expansion of real-time monitoring, anomaly detection, impact analyses, and mitigation (RAIM) framework that emphasizes on the resulting impacts, both on steady-state and dynamic aspects of power system stability. Hypothetically, we associate the combinatorial analyses of steady state on substations/components outages and dynamics of the sequential switching orders as part of the permutation. The expanded framework includes (1) critical/noncritical combination verification, (2) cascade confirmation, and (3) combination re-evaluation. This paper ends with a discussion of the open issues for metrics and future design pertaining the impact quantification of cyber-related contingencies

Power quality and electromagnetic compatibility: special report, session 2

The scope of Session 2 (S2) has been defined as follows by the Session Advisory Group and the Technical Committee: Power Quality (PQ), with the more general concept of electromagnetic compatibility (EMC) and with some related safety problems in electricity distribution systems. Special focus is put on voltage continuity (supply reliability, problem of outages) and voltage quality (voltage level, flicker, unbalance, harmonics). This session will also look at electromagnetic compatibility (mains frequency to 150 kHz), electromagnetic interferences and electric and magnetic fields issues. Also addressed in this session are electrical safety and immunity concerns (lightning issues, step, touch and transferred voltages). The aim of this special report is to present a synthesis of the present concerns in PQ&EMC, based on all selected papers of session 2 and related papers from other sessions, (152 papers in total). The report is divided in the following 4 blocks: Block 1: Electric and Magnetic Fields, EMC, Earthing systems Block 2: Harmonics Block 3: Voltage Variation Block 4: Power Quality Monitoring Two Round Tables will be organised: - Power quality and EMC in the Future Grid (CIGRE/CIRED WG C4.24, RT 13) - Reliability Benchmarking - why we should do it? What should be done in future? (RT 15

Very long distance connection of gigawatt size offshore wind farms: extra high-voltage ac versus high-voltage dc cost comparison

This study presents a cost comparison between commercially available high-voltage DC (HVDC) and extra high-voltage AC shore connection (±320 kV voltage source converter and 420 kV-50 Hz single-core and three-core cables), for a 1 GW offshore wind farm cluster, considering transmission distances up to 400 km. The HVDC system is a point-to-point connection whereas multiple AC intermediate compensating stations are envisaged for AC when needed. Capital costs are evaluated from recently awarded contracts, operating costs include energy losses and missed revenues due to transmission system unavailability, both estimated using North Sea wind production curves. Optimal AC intermediate compensation, if any, and reactive profiles are also taken into account. Resultsshow that HVDC has lower transmission losses at distances in excess of 130 km; however, due to the combined effect of lower AC capital cost and unavailability, using three-core aluminium cables can be more convenient up to 360 km distance

Comprehensive Overview on HVDC Converter Transformer Design: Additional Discussions to the IEC/IEEE 60076-57-129 Standard

HVDC has been chosen as an economical and technical solution for power transmission through long distances, asynchronous interconnections and long submarine cables crossing. Despite DC transmission benefits to power systems, the converters non-linearity produces undesirable effects to the converter transformer in service, mainly listed in the technical standard IEC/IEEE 60076-57-129. However, additional discussions and complementary information can be found in a plurality of references, which are brought in the article under a comprehensive overview perspective. Some design solutions deal with these effects increasing the technical margins, which have direct influence on manufacturing costs and transformer reliability and availability levels. This article goes through the main topics pointed by the standard and the references, investigating their consequences in the converter transformer operation, in order to provide a comprehensive tutorial on design solutions and considerations to deal with those undesirable effects

Modular multilevel converter losses model for HVdc applications

Multi-terminal high voltage dc (HVdc) grids can eventually became a feasible solution to transport energy to remote and/ or distant areas and its exploitation depend, among other things, on the performance of the converter terminals. Therefore, to optimize the power transmission strategy along such a grid, it is necessary to recognize the efficiency of all the converters in all points of operation, namely with the different load conditions. In this vision, the aim of this work is to provide the methodology to model the modular multilevel converter (MMC) efficiency by means of a mathematical expression that can describe, over a broad range of active and reactive power flow combinations, the power losses generated by the semiconductors. According to the presented methodology, a polynomial-based model with a reduced number of coefficients is deducted, in such a way that can be directly used for optimal power flow (OPF) studies. The accuracy of the proposed model is characterized by an absolute relative error, at the worst scenario, approximately equal to 3%.Postprint (author's final draft

Dissolved gas analysis equipment for online monitoring of transformer oil: A review

Power transformers are the most important assets of electric power substations. The reliability in the operation of electric power transmission and distribution is due to the correct operation and maintenance of power transformers. The parameters that are most used to assess the health status of power transformers are dissolved gas analysis (DGA), oil quality analysis (OQA) and content of furfuraldehydes (FFA) in oil. The parameter that currently allows for simple online monitoring in an energized transformer is the DGA. Although most of the DGA continues to be done in the laboratory, the trend is online DGA monitoring, since it allows for detection or diagnosis of the faults throughout the life of the power transformers. This study presents a review of the main DGA monitors, single- or multi-gas, their most important specifications, accuracy, repeatability and measurement range, the types of installation, valve or closed loop, and number of analogue inputs and outputs. This review shows the differences between the main existing DGA monitors and aims to help in the selection of the most suitable DGA monitoring approach according to the needs of each case.This research was funded by the EU Regional Development Fund (FEDER) and the Spanish Government under RETOS-COLABORACIÓN RTC-2017-6782-3 and by the University of Cantabria Industrial Doctorate 19.DI12.649

Field validation of gap-type overhead conductor creep

Gap-type overhead conductor sag-tension calculations based on experimental conductor creep tests are based on stress-strain and metallurgical creep tests. Although for bi-metallic conductors, these tests are carried out for both the core and the full conductor, for gap-type overhead conductors the aluminum metallurgical creep is usually neglected and the full conductor metallurgical creep is not carried out. The purpose of the presented study is the validation of these calculation methods. For this purpose, field measurements have been obtained in a pilot line in operation. The gap-type conductor installation process has been measured and the conductor creep has been monitored during three years of line operation. In order to model relevant events such as the pre-sagging and sagging steps during the installation, and ice and wind events during the operation, a flexible sag-tension calculation method has been used. Besides, the widely used graphical sag-tension method has also been evaluated, obtaining similar results as the flexible method. The tension-decrease is used as the indicator of the creep. The calculated and measured tension-decrease values are close. Therefore, it is concluded that the sag-tension calculations based on experimental conductor creep tests are valid to represent the actual creep of the conductor in operation.This work was supported by the Ministerio de Economía, Industria y Competitividad, Spain, [DPI2013-44502-R and DPI2016-77215-R (AEI/FEDER, UE)]; and by the University of the Basque Country UPV/EHU [EHU16/19]

An overview of HVDC technology

There is a growing use of High Voltage Direct Current (HVDC) globally due to the many advantages of Direct Current (DC) transmission systems over Alternating Current (AC) transmission, including enabling transmission over long distances, higher transmission capacity and efficiency. Moreover, HVDC systems can be a great enabler in the transition to a low carbon electrical power system which is an important objective in today’s society. The objectives of the paper are to give a comprehensive overview of HVDC technology, its development, and present status, and to discuss its salient features, limitations and applications.</jats:p

Contractors as modern Master Builders: Virtual Design and Construction as an enabler of meaningful experiences to project teams for achieving optimized substation management

Effective substation management should include engineering and construction costs. While the construction process has to be methodically planned and sequenced to achieve optimized construction costs, substation designers play a vital role for delivering cost-efficient substations. Integrated design and construction has been proposed as a way to achieve effective project management, which historically viewed, was a responsibility of a “master builder”, thus causing Contractors to identify themselves as “master builders”. As EPC is a highly competitive arena, Contractors are looking for ways to differentiate themselves from their competitors. Some are turning to 3D technologies, while others turn to the design-construction integration. Virtual Master Builder (VMB) supports both 3D technologies and the designconstruction integration. Due to a global shortage of worldwide available expertise, Contractors turn to education and training of their employees. While education aims at providing basic skills, training aims to provide the skill necessary to do the job. This paper examines these basic skills as a part of personal mastery before defining organizational learning as a key organizational competence. Physical Virtuality realm is seen as a fruitful ground for staging of memorable and transformational experiences leading towards achieving “accelerated learning”, and especially 4D models as representations of a “space-time” environment. The project case of Skopje 4 SS 380/110 kV rehabilitation is given as an example of 4D models usage. Project Engineering is seen as a middle ground between engineering and management in order to achieve goals of effective substation management and cost-efficient substation solutions. Project teams are seen as Virtual Design and Construction (VDC) users to achieve these goals

The Applications of Blockchain Technologies to Electricity Markets

This paper is a summary of the CIGRE Technical Brochure 824 The Role of Blockchain Technologies in Power Markets [17]. The work of the contributors to the Technical Brochure is recognised. It is proposed to follow up this work in a new working group with a more in-depth look at the potential applications for blockchain in the area of energy trading