Overview of the structure of reliability standards
Over the years, the North American Electric Reliability Corporation (NERC) has adopted a large number of standards that cover a broad range of subjects related to Bulk Electric System reliability in North America. They set out a large number of requirements, which must be met by any company performing one or more of the functions defined in the NERC Reliability Functional Model (presented in Reliability News No. 6).
The standards deal with many different topics, such as transmission planning and operations, physical and cyber security of facilities, data transmission and even communications.
There are 14 families of standards. Thirteen fall into the category of operational (OPS) issues, while the fourteenth belongs to its own category, critical infrastructure protection (CIP). Taken as a whole, the standards are designed to make reliability a central concern for all functional entities. The reliability standards complement one another, since the system reliability responsibilities of different functional entities are spread across multiple standards.
Critical Infrastructure Protection standards
Information technology plays an essential role in the operation and maintenance of power generation and transmission facilities. However, together with grid automation, it exposes facilities and control centre systems to the risk of intrusion. To reduce these risks, the Critical Infrastructure Protection (CIP) standards were created to define, categorize and secure the critical infrastructure and assets needed to operate the North American Bulk Electric System. They also address system facility sabotage detection and reporting, personnel training, security management and disaster recovery planning.
Operating standards are organized into the families listed below, which address operations, planning, maintenance, operations coordination, reliability parameter control and other tasks to maintain power system reliability:
BAL – Resource and Demand Balancing
In the operation of a power system, offer (generation) and demand (consumption) must be balanced at all times. This balance makes it possible to maintain the stable system frequency required by all electrical equipment connected to it (60 Hz in North America). Since consumer demand for electricity varies constantly, the power generation of generating stations must constantly be adjusted accordingly. These standards cover activities to maintain a stable power system frequency by balancing power demand and supply in real-time.
COM – Communications
Efficient procedures to maintain communication between the system control centres and interconnected entities are essential to ensuring the power system reliability. These standards are intended to ensure the proper operation, redundancy and route diversity of telecommunications systems to permit communication at all times when a communication system fails. They also require the implementation of procedures to prevent misunderstandings between operators or a lack of communication that could lead to switching that could in turn threaten system reliability.
EOP – Emergency preparedness and operations
These standards set out the measures needed to safely handle emergency situations and re-energize the system as quickly as possible. Their purpose is to provide a framework for the process and ensure that all actions are appropriate and coordinated.
FAC – Facilities design, connections and maintenance
The design of generation, transmission and distribution facilities must follow good practices, and the connection of new facilities must be controlled. Thus, the goal of these standards is to bring uniformity to the North American electricity sector. They apply to all entities involved in electric system reliability through the design, connection or maintenance of generation, transmission or distribution facilities.
INT – Interchange scheduling and coordination
These standards deal solely with interconnection reliability. They do not address the business side of interconnections, which is governed by the Open-Access Transmission Tariff (OATT) approved by the relevant regulatory bodies. Consequently, their objective is to ensure that each interchange is coordinated and carried out without threatening reliability.
IRO – Interconnection reliability operations and coordination
IRO standards apply to the operation, coordination and reliability of interconnections. They do not consider interconnection lines, but rather the four North American interconnections governed by NERC reliability standards (East, West, ERCOT and Québec). The Québec Interconnection includes all of the interconnected systems and entities that operate on its territory, such as Rio Tinto Alcan, Hydro-Sherbrooke and Énergie La Lièvre. Given the large number of organizations, proper coordination between the entities is essential to facilitate operations, promote clear communication and thereby achieve the reliability target. These standards provide specific guidelines on how to achieve that objective.
MOD – Modeling, data and analysis
These standards focus on the need to maintain awareness of available transmission system capability and future power flows over both one’s own system and neighboring systems. They therefore provide guidelines for modeling, data and analysis needs.
NUC – Nuclear
These standards ensure that nuclear plants operation and shutdown are safe. Since there is no nuclear plants in Quebec, these standards are not applicable in the Québec Interconnection.
PER – Personnel performance, training and qualifications
PER standards aim to ensure that interconnected transmission systems are operated by personnel that is qualified, competent and given sufficient authority to direct or order required operations. System operators must have complete knowledge of the reliability standards on operation and ensure they are applied under all circumstances to maintain a high level of reliability. These standards underscore the importance of the qualification, knowledge and training of power system operations personnel.
PRC – Protection and control
PRC standards deal with the protection of power systems. Since they regulate the operation and configuration of protection systems (relays, special protection systems, etc.) and associated maintenance intervals, they must be respected to ensure the security of North American power systems.
TOP – Transmission operations
These standards are intended to ensure that entities responsible for transmission system operation have the necessary tools and authority for their function; plan and coordinate their activities; and are prepared to handle events that could cause system instability. In particular, they require Transmission Operators to adequately monitor System Operating Limits (SOL).
TPL – Transmission planning
TPL standards apply mainly to Planning Authorities. They address system response in normal conditions and the faults to simulate to ensure the system is robust and reliable. They provide a framework for system planning and establish the allowable criteria for the most severe operating conditions.
VAR – Voltage and reactive
A voltage collapse could cause trips and lead to a system outage, while excessive voltage levels increase the risk of equipment failures. These standards are needed to ensure, in real time, that system voltage and reactive power remain within prescribed limits.