Power system operation and control

Introduction

The year 2021, from the point of view of the Electric Power Systems Operation, seems to have been characterized by the stabilization of the rebirth of normal conditions as, throughout the year, the control of the COVID-19 pandemic gained space.

Notably, what caught the attention of observers was that this rebirth took place against a backdrop of major technical changes and consumer behaviour that was totally different from what was known and with a certain degree of inevitable unpredictability.

It seemed natural to see the resumption of daily consumption curves at higher values, already started in the second half of 2020, after the drastic reduction experienced by the lockouts that came with the pandemic. However, the growth of Distributed Energy Resources, close and even promoted by the consumers themselves, began to bring distorted characteristics of this curve, a consequence, mainly of the action of distributed photovoltaic generation. The operation had to learn to live with a demand that, contrary to expectations, did not grow as much or even reduced with the sunrise and the daily awakening of people and its electric energy consumption and with accentuated ramps of consumption at the end of the periods of the day illuminated by the Sun. And the challenge, of course, comes from having this situation or not, varying daily because of greater or lesser cloudiness during the day.

And, despite this scenario of returning to focus on technical challenges, the emergence of variants of the coronavirus at the end of 2021 and in the first months of 2022, came to resume the intensity of concern with the health of the operating teams and with the need to have healthy technicians to form the teams. Fortunately, due to the less aggressiveness of these variants and/or the action of the increasing application of vaccines, the symptoms from these variants proved to be much reduced in severity and duration, causing less inconvenience to the formation of the teams, if compared to those verified at the beginning of the pandemic.

Practically independently of the above aspects, the different known movements and some less predictable, but equally integral to the group that makes up the so-called Energetic Transition, follow their path, although with different speeds and characteristics in different countries and systems.

The penetration of wind and photovoltaic energy, both in distribution systems and in transmission networks, in different installed powers and voltages seems to be far from having its speed reduced. The operation already faces challenges to avoid or minimize the necessary reductions in the total generation of these plants, at certain times of the day, either due to electrical restrictions that still exist in the transmission systems or even due to insufficient demand to try to use the entire amount of generation of these new intermittent renewable plants together with the existing inflexible generation (thermal and hydraulic). Other well-known challenges of coexistence with intermittency and low levels of inertia in the operation remain.

It is precisely with the aim of making the most of intermittent renewable energies, when they are available, that the use and developments of technology in energy accumulators have been highlighted.

The use of electrochemical batteries at different levels of charge, power and voltage, which seems to be a better dominated technology, has been trying to establish itself by obtaining more competitive costs for these products, compared to the losses caused by the waste of unused energy from sources flashing.

And the production of Hydrogen (especially that which has the proven characteristic of being Green Hydrogen) has been gaining space not only for its environmental and sustainability appeal, but also for the evolution of production technologies and conversion into electric energy or other direct uses of this substance.

New challenges are expected for the operation of the systems as the use of Energy Accumulators, of different types and technical characteristics, has been gaining ground. It should not be forgotten that the first challenge of programming the optimal use of accumulated energy already coexists with the possibility of interfering with the load curve, facilitating the necessary operational controls when programming the periods for charging the energy to be accumulated. Nothing different from the "engineering spiral" where the generators of new challenges are the new technologies that emerged in response to the challenges previously faced. And the field of action of our Study Committee C2, Operation, remains the meeting point where all technical aspects and challenges meet.

In the field of main events of the 2021/2022 period, we proudly highlight the excellent updated content presented at the 2021 CIGRE Virtual Centennial Session which, if on the one hand was already known since the previous year for the most part, allowed new debates that brought great interest for the celebration of the 100th anniversary of CIGRE.

In addition, our participation in the CIGRE KYOTO 2022 Hybrid Conference was also highlighted, even though our SC.C2 was not one of the leaders of the organization, due to the high level of the articles presented and discussed in April 2022.

But it is with great anticipation and happiness that we are preparing for the great face-to-face meeting at the Palais de Congrès, starting on August 28, 2022, at the opening of CIGRE Session 2022. From our part, we already have a collection of more than 50 articles of excellent quality and great variety of topics covered, within the scope of SC.C2, anticipating a great Group Discussion Meeting, this time, again, live, at the Bordeaux Amphitheatre.

And if, earlier in this text, we already talked about the technological advances that so many changes bring to the operation, we remember that the challenges that equipment and nature, with their meteorological phenomena, insist on presenting us with unavoidable disturbances being their direct consequence. We are already scheduling debates on Large (in numbers and/or technical importance) Disturbances that will make up our traditional Workshop as part of CIGRE Session 2022.

Below, in this text, is a summary of our information regarding the period 2021/2022 that we would very much like readers to use as a "warm up" for our face-to-face reunion in the last week of August 2022!

SC C2 Mission and Scope

The scope of the SC C2 covers the technical, human resource and institutional aspects and conditions for a secure and economic system operation of power systems in a way that is in compliance with requirements for network security, against system disintegration, equipment damages and human injuries, and security of electricity supply.

Unbiased and high-quality knowledge dissemination to the power systems community by CIGRE Study Committees is a strong pillar for the development and performance of power systems, especially in the increasingly integrated environment. This applies not only to current but also to future power systems. SC C2 therefore needs to understand, use and integrate results from other Study Committees to assure that technical concepts can be applied in real-time in various contexts and implemented by the System Operators. An area which is unique for C2 is however the dependence on good performance of human resources in performing operational planning and real-time system operation. In these respects, SC C2 embraces a wide range of competence areas and interfaces to other disciplines.

The mission of SC C2 can be summarised in the following four points:

1. To facilitate and promote knowledge dissemination and worldwide collaboration in the field of system operation and control, providing adequate conditions for progress of engineering.
2. To facilitate unbiased technical information exchange, integrating solutions and recommendations for system operations issues and problems. These first two points are achieved among others by the publication of Technical Brochures and papers, delivering tutorials, and participating in conferences, symposia and colloquia.
3. To prepare for the foreseen future challenges by integrating and consolidating available knowledge and taking into account the usage of new and proven technologies. For example, the joint effort of several Study Committees in establishing Joint Working Groups, where different expertise and knowledge is combined, as well as in writing multi-disciplinary Reference Papers.
4. To engage and encourage young members to increase their involvement in the SC activities. By integrating them into Working Groups, a bridge between the young experts and experienced members can be built. SC C2 aims to connect, when possible, a young member to a mentor from the same SC and NC. This gives the opportunity to support the young member's development in a supervised way.

Structure

An overview of the structure of SC C2 is given in Figure 1. The SC has 27 regular members and 12 observer members, 7 active Working Groups of which 1 is a joint Working Group with another CIGRE SC, and 3 Advisory Groups.

The Strategic Advisory Group, consisting of the SC Chair, Secretary and other SC C2 experts, deals with SC strategy and updates the scope of the Technical Directions. The Publication Advisory Group is responsible for the revision of synopses and papers for CIGRE activities where SC C2 plays a role.

The Tutorial Advisory Group (TAG) coordinates the development, planning, quality assurance and delivery of tutorials for conferences, symposia, colloquia and webinars. There are around 184 experts from 42 countries actively involved in SC C2 activities.

Figure 2 gives an overview of the geographical distribution of SC C2 members.

Main technical directions

SC C2 has defined three Technical Directions (TD) to address important emerging factors that will influence and define new requirements on the System Operation performance.

TD 1: Real-time System Operation and Control

• Wide area control, supervision and increased coordination: integration of regional and national grids into large control areas
• Operation and control of new technologies and system protection schemes
• Increased power system controllability, observability, flexibility and exchange of information, both at transmission and distribution level: e.g. voltage control, frequency control
• Interaction between market mechanisms and power system operation, e.g. ancillary services and congestion management
• Operational real-time security and risk assessment
• Maintaining Security of Supply, Emergency control and restoration procedures and tools
• Information and data exchange in real-time operation

The Working Group C2.18 and the Joint Working Group C2/C5.06 address topics in this TD 1.

TD 2: System Operational Planning and Performance Analysis

• Impact on system operation from new generation mix, storage and changes in electrical load behaviour
• Close to real-time operation, crucial for a successful and secure real-time operation, performed both by operational planners and control room operators
• Security assessment in Operational Planning, including coordinated activities
• Assessment of monitoring, control and protection functionalities, including development of new operational strategies
• Emerging Operational Issues for Transmission and Distribution Interaction
• Impact assessment on integration of new technologies
• Blackout integral analysis, defence plans, resilience schemes and restoration strategy considering the evolving environment
• Reliability, network security principles and generation and transmission adequacy
• Operational requirements in Grid Codes
• Information and data exchange in the operational planning timeframes

The Working Groups C2.24 and C2.26 address topics in this TD 2.

TD 3: Control Centre Infrastructure and Human Resources for System Operation

• Knowledge management and Operator training
• Operator training simulator and other training tools
• Control Centres processes, methods, tools and organisation development
• Tools for decision support and situational awareness
• Integration and exchange of information in system operations and data management
• EMS/SCADA systems, specifications and experiences
• WAMS system requirements and their integration within CC
• Control Centre reliability and resilience
• Information, cyber-security and other vulnerability aspects on control centres

The Working Groups C2.39, C2.40 and C2.42 address topics in TD 3.

However, it is relevant to point out that some of the WGs touch upon more than one technical direction.

Working Groups Report

Below a short update of the Working Groups active in 2021-2022 is provided.

WG C2.18 Wide Area Monitoring Protection and Control Systems – Decision Support for System Operators

The Working Group is writing an additional Technical Brochure, which will continue the work already published by WG C2.17 in TB 750 by going one step forward in extending the wide area monitoring to system protection and control. Therefore, after identifying the current experience and control room practice, the brochure describes a flexible and scalable system architecture and identity possibilities for standardisation in event recording and analysis. The brochure also focuses on the interfacing of WAM systems with EMS, SCADA and data base systems and on requirements for communication channels. Further on the process of WAMPAC implementation up to recommendations for control room measures are addressed. Possibilities for the use of PMUs for special protection schemes (SIPS) and usage for interactions with HVDC links or inverter-based generation are further discussed and the use of WAM tools for component compliance testing is addressed. Finally, an overview of advanced R&D activities already integrated into system operation practices is provided. As the WG members are a good mix between solution vendors, academia, system operators and consultants, pragmatic and comprehensive approaches for further developments or already existing solutions are being documented.

For the analysis of the July 24^th 2021 system separation in the Continental European (CE) power system once more WAM recordings have been a key element during the related investigation activities.

The CE power system was enlarged on March 16th 2022 by the two additional power systems of Ukraine and Moldova which were before connected to the Russian and Byelorussian interconnected system. For the subsequent on-line and off-line dynamic stability assessment the common intelligent use of the different existing CE-WAM systems have been proven to be of substantial importance. Under the umbrella of ENTSO-E the use of those tools is undergoing a permanent process of efficiency and professionalism common use in order to cope with the current challenges.

WG C2.24 Mitigating the risk of fire starts and the consequences of fires near overhead lines for system operations

The WG C2.24 is made up of utility representatives, consultants and academics, from 4 countries. The Executive Summary of the work of WG C2.24 was published in Electra nº 322, June 2022. Technical Brochure 868 includes the results of the survey of a total of 27 transmission and/or distribution utilities on wildfire (bushfire) risk management practices. The best practice results of the study have been collated into the Emergency Management Prevent, Prepare, Respond and Recover framework for bushfire risk management to assist utilities with strategies to manage the risk of fire starts from powerline assets, as well as manage the impacts of fires on powerline assets. Of particular interest is the use of pre-emptive power shutdowns. Utilities have to determine a “risk appetite” level which balances the adverse impacts on customers of shutting off power with the risk of avoiding starting a wildfire – refer to Figure 3. With reference to Figure 4, in determining the balance point, utilities need to consider:

• FR_i is the Feeder Risk of the ith feeder
• Cust Numi is the number of customers supplied by the ith Feeder
• Outage Durationi is the duration of the power shutdown for Feederi
• IF_i is the “Inconvenience Factor” for Feederi

A tutorial on the work of WG C2.24 is scheduled for the 2023 Cairns Symposium and the WG will be kept active until then.

WG C2.26 - Power system restoration accounting for a rapidly changing power system and generation mix

This Working Group, approved in March 2019, aims to identify and manage emerging risks on system restoration, investigate opportunities for increased utilisation of new and emerging technologies during system restoration, and enable system operators and network owners to continue to execute a successful system restart when required despite the rapidly changing generation mix. The work carried out so far in this WG includes discussion on system restoration practices and challenges in more than 10 countries from those represented in the WG, the role of inverter-based resources in system restoration either as a black starter or to support system restoration, tools and techniques for analysing system restoration including real-time and offline electromagnetic transient simulation and fast decision support tools, and physical testing demonstrating the capability of VSC HVDC during restoration. Emerging areas recently started include system restoration subject to cyber-security, loss of control centres, and pandemic situations. Other immediate areas of work include power system modelling and physical testing to better understand the roles and limitations of various types of inverter-based resources during system restoration. The WG is considering to present a tutorial or write a CSE paper. The TB is planned to be published in Q3 2022 due to the impact of COVID-19 on the activities of the WG.

WG C2.39 - Operator Training in Electricity Grids at Different Control Levels and for Different Participants/Actors in the New Environment

The Working Group started its work in August 2018. By the end of 2019, the final version of Document No. 1 was completed and constitutes the first chapters of the Technical Brochure, the expected final product of the WG. This document clarified the existing situation on the subject based on the scenarios presented by the 16 companies surveyed. From there, the group began to work on the 9 items considered important for greater detailing of updated training based on simulator exercises. Research and analysis of the results of the responses were carried out and, today, the draft versions of each of these items are making up each of the chapters of the Technical Brochure that is in its draft form. Throughout July and August 2022, revisions to these texts have been made by the group members so that it is expected that much of this content will be completed at the meeting of the Working Group participants at the first face-to-face meeting since October/2019 which will take place during the CIGRE Session 2022, in Paris.

It is expected that by the end of the year, the Technical Brochure will be in its final version.

WG C2.40 - TSO-DSO Co-Operation – Control Centre Tools Requirements

The paradigm shift in the configuration of the power system with a high penetration of distributed renewable generation connected at the DSO level creates a new dimension in TSO-DSO coordination practices and procedures. The role of this WG, approved in June 2018, was to specify a set of control centre tools and related IT platforms for both the TSO and DSO to manage and operate this newly evolved power system. A critical aspect that must be addressed is that the tools must enable a high level of cooperation between the TSO and DSO. Interoperability between the tools should be developed considering different time-horizons (at least real-time and short-term operational planning) and different services. At the conclusions of its work the Working Group had 23 experts from 12 different countries.  The Working Group published a paper at the Paris 2020 session (C2-205 TSO-DSO Cooperation: Control Centre Tool Requirements) while the final technical brochure, number 845, was published in October 2021. A tutorial will be delivered in August 2022, during the 2022 CIGRE Session, and the WG will be kept active until then.

WG C2.42 The impact of the growing use of ML-AI in the operation and control of power networks from an operational perspective

This main goals of this new WG are to i) conduct an impact assessment of the usage of novel and state-of-the-art AI technologies on System Operations and Operators decision-making, ii) the identification of associated risks and core requirements for system operations (in terms of digitalization, data and IT processes), iii) survey ongoing developments in power system industry (as well as other industries) to capture operational learning or experiences so far with AI, and iv) identify current trends for further development and integration. The WG started its activity in March 2022, after the selection of members from the nominees. A set of potential use cases for AI in power systems operations were already identified and the plan is to conduct a literature review until November 2022 for the technical brochure (planned to be published by December 2023) and conduct a survey with System Operators in Q4 2022. The Working Group has 25 experts (R&D / Academia from AI community and power systems, system operators, industry, regulators, policy makers for digitalisation) from 20 different countries.

JWG C2/C5.06 The Impact of Electricity Market Interventions by System Operators during Emergency Situations

The JWG started its work in October 2021 and adopted a schedule of having 2 hour on-line meetings every 3-weeks which turns out to work well. First meetings were used to extensively discuss the terms of reference and how this exactly defines the way the work should be organised and what will be the deliverables. It turned out that the terms of reference were not that water tight as expected, this resulted again in discussions when drafting a survey to collect information related to our subject. Mainly the discussion came to the questions “what is an intervention“ and “what is an emergency”. However, the expectation is that via the responses to the survey we will get a better understanding of how this is assumed in different parts of the world. The responses to the survey were collected until end of June 2022 and are analysed subsequently to serve as the (important) input material for the Technical Brochure. You may expect to read the findings in the Technical Brochure that is planned to be ready in the summer of 2023. Before than the plan is to deliver an article or paper to already inform about the first findings and hopefully give some appetite for the actual Technical Brochure.

Past Tutorials & Webinars

During the 2021 CIGRE Virtual Centennial Session, on Wednesday, 25 August 2021, Jens Jacobs and members of WG C2.25 delivered a tutorial titled "Operating Strategies and Preparedness for System Operational Resilience" on behalf of SC C2. As this tutorial was the last activity to be completed by WG C2.25, it was disbanded soon after.

During the 2022 CIGRE Symposium in Kyoto, Japan, on Tuesday, 05 April 2022, Mpeli Rampokanyo and members of JWG C2/C4.41 delivered a tutorial titled “Impact of high penetration of inverter-based generation on system inertia of networks” on behalf of SC C2. As this tutorial was the last activity to be completed by JWG C2/C4.41, it was disbanded soon after.  

Joint Technical Activities

The SC also participates in other Working Groups that are being led by other SCs. SC C2 is part of Joint Working Groups C6/C2.34, D2/C2.48, C4/C2.58/IEEE and C4/C2.62/IEEE. The SC has active liaisons in the Working Groups A1.65, C1/C4.36, C6.36 and C6.40.

Publications

The following publications have been made since August 2021 as result of work carried out by SC C2 Working Groups:

WG C2.26 and WG C2.39 are finalising their Technical Brochures, which are expected to be published in 2022.

Awards

The following SC C2 members received CIGRE awards in 2021:

• Vinay Sewdien (Netherlands) was awarded the Centennial TC Award;
• Susana de Graaf (Netherlands), Marija Zima (Switzerland), Anjan Bose (USA) and Renuka Chattergee (USA) were awarded the Pioneer e-session Achievement Award;
• Anjan Bose (USA) was awarded the CIGRE Medal;
• Vinay Sewdien (Netherlands) was awarded the Next Generation Network Significant Contribution Award.

Workshops, Conferences and Seminars

From August 2021 onwards, the following SC C2 members took part in events: 

Jayme Darriba Macêdo, Chair of SC C2, delivered a keynote speech titled "Desafíos para la integración en la operación de los sistemas de fuentes no sincrónicas y DER", in the “Agenda FISE-CIGRE CONFERENCE 2021 - Nuevos retos, nuevos caminos para la sostenibilidad”, organized by FISE and CIGRE Colombia NC, on November,18th 2021.

Future Activities

The next events for SC C2 are:

• CIGRE Session 2022: The Large Disturbances Workshop, organised jointly with SC C5, will take place on Monday, 29 August 2022. The following presentations are confirmed for the workshop:

• Michael Power and members of WG C2.40 will present the tutorial titled “TSO-DSO cooperation – Control centre tools requirements” on Thursday, 01 September 2022, during the CIGRE Session 2022.

• 2023 CIGRE Symposium – 4-7, September, 2023 – Cairns, Australia - Chair: SC C2 and SC C5 – B1, B3, B5, C1, C4, C6, D1 and D2.

• Franco Crisci and members of WG C2.24 will present the tutorial titled “Mitigating the risk of fire starts and the consequences of fires near overhead lines for system operations” during the 2023 CIGRE Symposium in Cairns, Australia, in September 2023.

Conclusions

It's time for our reunion!!

Although persistent, the current situation of the pandemic in a global way allows us and, therefore, we invite ourselves to return with the most "heated" and, we hope, always more productive way of exercising the motivators of CIGRE's work.

That the sharing of the knowledge created happens in person, with debates, disagreements, joining forces and generating more knowledge, as a consequence.

May this return to face-to-face meetings give an even greater boost to our ability to successfully face the challenges of the Energy Transition with all its new technologies and new needs for adapting the System Operation, ensuring our greater goal of delivering electricity. increasingly important, for the increasingly electrified society!

See you in Paris...

Contact

• Contact of the Chair and/or the Secretary of the Study Committee