System Protection Schemes: Limitations, Risks, and Management

(PSERC) is a multi-university Center conducting research on challenges facing the electric power industry and educating the next generation of power engineers. More information about PSERC can be found at the Center's website: Notice Concerning Copyright Material PSERC members are given permission to copy without fee all or part of this publication for internal use if appropriate attribution is given to this document as the source material. This report is available for downloading from the PSERC website. We very gratefully acknowledge the inputs received from the industry experts, (MISO), for their insightful comments, which were very helpful in shaping this work. Special protection schemes (SPS), known also as remedial action schemes, are designed to detect abnormal system conditions and take predetermined, corrective action (other than the isolation of faulted elements) to preserve system integrity and provide acceptable system performance. Today, in many parts of the world, SPS represents a viable planning alternative to extending transmission system capability. Although SPS deployment usually represents a less costly alternative than building new infrastructure, it carries with it unique operational elements among which are: (1) risks of failure on demand and of inadvertent activation; (2) risk of interacting with other SPS in unintended ways; (3) increased management, maintenance, coordination requirements, and analysis complexity. Additionally, there is a dearth of simulation and assessment tools for performing reliability studies of SPS and enable planners to evaluate the operational complexity that SPS brings into the system along with its various economic and operational advantages. So the objective of the proposed work is to provide a structured framework for identifying limitations of SPS deployment within a system, and assessing SPS risks and develop proper standards and practices for maintaining SPS reliability over its lifetime. One of the highlights of the report is the unique assessment framework proposed based on both a process view and a systems view to identify risks and associated consequences for SPS. The process view based framework will view SPS in terms of a process which considers all the building blocks starting with the actuating signals, the equipment and logic used to operate on those signals, communication equipments and so on till the final action. The system view framework will view SPS in terms of its position in and impact on the power system in which it exists. This framework proposed is one of the significant contributions of this report, as even though a particular …