Dale Finney

JEC 61850 - A Practical Application Primer for Protection Engineers

This paper reviews concepts proposed by the IEC 61850 standard; protection and control (P&C) aspect in particular. The standard describes building blocks meant to facilitate the general idea of migrating traditionally hard-wired P&C connections and configurations into the realm of software, while opening considerable opportunities for engineering and labor savings. The underlying principle is that the newly introduced complexity resides in software, and therefore, new software tools will reduce or eliminate some of it, simplifying both the engineering and deployment, thus resulting in a substantial net gain. IEC 61850 has received considerable attention in recent years, but vast majority of publications are written around the theme of the intelligent electronic device (IED), and rest at introducing the concept, reviewing selected details of IED implementations, and focusing on anticipated advantages. This paper is written for a traditional P&C engineer and reviews important practical questions that need to be answered, solutions worked out, and tools developed before the IEC 61850 concept could see its all-inclusive implementation

Distance Protection in Distribution Systems: How It Assists With Integrating Distributed Resources

The integration of distributed generation (DG) or distributed resources in the distribution system poses technical constraints for the electrical power system owner or manager. The addition of relatively large amounts of generation to the distribution system can potentially challenge the historical setting principles and design assumptions made in developing protection and control strategies based on overcurrent protection. The necessity and complexity of additional protection and control measures increase as the aggregate DG capacity within a potential island approaches or offsets the load within that island. In addition, the varying nature of DG availability and fault current capability must also be considered. The key issues discussed and associated with DG on the distribution feeder include anti-islanding, temporary overvoltages during fault conditions, and loss of sensitivity of feeder overcurrent protection for long feeders. As the distribution system evolves to accommodate more DG, the design and implementation of the feeder protection must also evolve. This paper presents the use of distance relays for distribution protection to solve some of the DG integration problems. This paper provides real-world event report data to further demonstrate the performance of distance protection on the distribution system. A relative cost comparison between various feeder protection solutions is presented along with a discussion on options for education of distribution companies challenged with implementing distance protection for the first time.

Generator protection and ct saturation problems and solutions

This paper presents a new generator relay design, stator differential function in particular, coping with extreme cases of current transformer (CT) saturation: both ac saturation under large currents and/or residual flux; and dc saturation under low currents but large and long-lasting dc components. The algorithm is a subcycle algorithm with fastest times reaching half a cycle including overall response of the relay hardware. Analysis of the response of a traditional differential function under CT saturation is included to provide setting guidelines for legacy relays.

Generator protection and CT saturation problems and solutions

This paper presents a new generator relay design, stator differential function in particular, coping with extreme cases of current transformer (CT) saturation: both ac saturation under large currents and/or residual flux; and dc saturation under low currents but large and long-lasting dc components. The algorithm is a subcycle algorithm with fastest times reaching half a cycle including overall response of the relay hardware. Analysis of the response of a traditional differential function under CT saturation is included to provide setting guidelines for legacy relays.

Fast and Secure Numerical Breaker Failure Protection

This paper presented two algorithms for enhanced numerical BF protection. The fast reset algorithm for current-based BF detector is based on differentiating between the rotating pattern of a fault current and the decaying pattern of a subsidence current. The algorithm is simple, yet very fast and robust. It uses few factory constants, but they have well defined meanings and can be easily fine tuned in any particular implementation that follows our approach. The algorithm can be further enhanced by recognizing that when the current vector stops rotating and starts decaying due to subsidence, it actually rotates at a significantly lower rate, but in the opposite direction compared with an alternating current. This reversal of the angular speed can be used to strengthen and speed up the algorithm