By David G. Hart, Juergen Holbach, Saman Alaeddini, Ashok Gopalakrishnan
From electromechanical to microprocessor based relays, historically, the approach has been to “set and forget” the settings. While settings may have been reviewed with new system additions or upgrades, human resource demands and other priorities often limit system wide settings reviews. When new North American Electric Reliability Corporation (NERC) requirements take effect, utilities will be required to perform periodic reviews of their Bulk Electric System (BES) relay settings to ensure proper coordination.
These emerging requirements place additional workload on the utility protection team. To achieve compliance, utilities need to evaluate how the new requirements will impact their existing processes and how to strategically implement new processes and tools.
NERC PRC-027-1 is in the approval process and will require utilities to periodically review their protection system coordination for the BES. Requirements include: (i) Implement a process for developing new and revised settings, (ii) Periodic review of protection system coordination and settings, and (iii) to follow the process defined in (i) for new settings. In implementing a settings management process, the utility needs to look at the process for updating the short circuit model, the process for reviewing the protection settings, and the process for communicating coordination issues with neighboring utilities. The periodic review must be performed every 6 years by studying the results of a coordination study, reviewing the bus short circuit values for deviations exceeding 15 percent, or some combination of the two methods.
So what type of issues should a utility consider when deciding on how to implement a compliance process? Some suggestions are offered below.
Considerations in Looking at Implementation
Implementing these new requirements will impact the protection team in several areas. Some items that may need to be evaluated include:
- Merging of Protection Teams – Over the years, several utilities with separate protection teams, and therefore, distinct protection philosophies, have merged to create larger entities. In looking towards the future, the combined entity will have to work towards a unified protection philosophy, including a thorough review of the process to be followed for achieving system-wide BES protection coordination.
- Evolution of Existing Processes – As the number of studies and the need to document compliance increases, protection teams need to look for improved efficiency to deal with the increased workload. In addition to PRC-027, protection teams need to look at how this and other compliance requirements will impact their existing processes and the tools to implement those processes. Is it possible to consolidate processes, implement system standards that allows one to utilize new or different tools to facilitate automation of processes? How are short circuit, asset management for settings records, and other systems interfaced to reduce manual human errors? Do existing tools meet the new needs, and should other process consolidation and improvements be considered?
- Base Case – For BES systems, the base case has several major components: the short circuit model, the relay settings, and the coordination review. In looking at each of these components, some items to consider include:
The first two items are related to using accurate information and are associated with the process of updating the appropriate systems. The last item concerning coordination is obviously dependent on the first two, but even with completely accurate input data the overall BES system coordination should be considered in more detail. Over the years, coordination reviews are not usually performed over a wide area. Further, primary system and protection system contingencies are considered in a very limited manner, resulting in latent protection issues that need to be addressed prior to establishing the base case.
- Is my system primary model updated and correct?
- Are the relay field settings the ones available for the coordination study?
- What is the level of confidence in the system coordination in the base case?
- Timeline – One of the major issues is to put a plan in place and start working on the overall implementation. As expected, it will take some time to conduct a review on how things are done today, create a plan for going forward, and implement the plan.
Obviously the implementation plan will also depend on these and other factors such as the utility budget, priorities, resources, and the size of the BES.
One of the major factors to consider is time. To review your existing processes and tools takes time and effort. Once completed, a plan can be created on how to move forward with new tools and processes to improve efficiency where needed. Depending on the system size, establishing a base case to review and update the system and relay data, as well as catch latent coordination issues requires not only to perform the studies but also to correct any discovered issues. In order to successfully meet these new workplace challenges and opportunities, getting a plan and timeline in place is the key.
David G. Hart, IEEE Senior Member, is Senior Director of Protection and Control at Quanta Technology. He has more than 24 years of experience in the power systems area and is responsible for overseeing Quanta Technology’s protection, automation and compliance projects with utilities across the globe. Dr. Hart began his career in R&D with ABB working on new protection algorithms. Later he worked as SVP with Elster and was responsible for the engineering, product management and quality departments. Prior to moving to Quanta Technology, he was the VP of Automation Solutions at ABB. Dr. Hart has over 25 patents in power system protection, control and AMI systems technologies. He received a PhD and MS degree in power system protection from Clemson University in 1991 and 1987, respectively. He received a BS degree in mathematics and physics from Wofford College in 1985.
Juergen H. Holbach, PhD, is Senior Director, Automation & Testing at Quanta Technology. He has more than 17 years of experience in design and application of protective relaying. He led the development project for the second generation of numerical line differential relays for a German relay manufacturer. As an application expert for transmission protection, he was responsible for approval test of transmission relays with utility customers around the world. Since 2000, he has worked in the U.S. as a product manager for protection relays. Juergen was one of the lead engineers on the first IEC 61850-based protection and control, multi-vendor projects in the U.S. (500KV Bradley Station-TVA). Juergen contributed to several working groups in CIGRE as well as in IEEE-PSRC and is the chairman of the "H5 Common format for IED configuration data" working group. He is also member of the IEEE-PSRC subcommittees "Relay Practices" and "Relay Communication". He published over a dozen papers at the major relay conferences in North America and is a member of the Georgia Tech Protective Relaying Conference Planning Committee. Juergen holds several patents in the area of protection relaying.
Saman Alaeddini is an advisor for protection, automation and control at Quanta Technology. He is a specialist in protection system modeling, energy storage technology, database management and analysis, design of autonomous systems, robotics and industrial processes. Prior to joining the company, Saman was engaged in real-world automation system implementation and maintenance through various programs at Honda of Canada Mfg., continuing education .NET programming at Ryerson University, and advanced machining program at George Brown College. Saman also has direct experience with several pilot demonstrations of energy storage technology applications assessment, and system impact studies of high level of renewable energy penetration in utility grids. Project experiences include, but are not limited to, various technologies, including solar PV, wind turbine, hydro power generation, as well as diesel and/or biogas engines .
Ashok Gopalakrishnan is Principal Advisor with Quanta Technology. He has over 17 years of industry experience, working in India and the U.S. He is highly experienced in the computer-aided analysis of electrical power systems. He has developed advanced automation techniques to help analyze complex protection coordination issues and is an expert in the usage/application of the CAPE software, having been intimately involved in its development for over a decade .