Summary Paper For Ieee C37.109-2023 Guide For Protection of Shunt Reactors
IEEE Power System Relaying and Control (PSRC) Committee Working Group K26 revised the Guide for Protection of Shunt Reactors. This summary paper introduces the revised guide IEEE C37.109-2023 to the industry. The WG members included Kamal Garg-SEL, Pratap Mysore-Ultieg, Ilia Voloh-GE, Gary Kobet-TVA, Bill Cook-Retired, Mukesh Nagpal-Burns&McDonald, Steve Conrad-Retired, David Caverly-Trench, Robin Byun-BPA.
Two basic shunt reactor applications considered in the paper for the protection are line or bus connected reactors and tertiary connected reactors. Line connected reactor types and configurations considered include dry-type, oil immersed, wye-connected, directly grounded, or grounded through a neutral reactor. Tertiary connected reactors are dry-type ungrounded Wye connected to the tertiary winding of a power transformer. The paper discusses various construction arrangements and its implications on protection designs. In addition, Variable Shunt reactors with tap changers and oil immersed, gapped Iron-core shunt reactors with auxiliary windings to provide station service in remote areas are introduced in the guide.
Paper highlights system considerations and switching issues, focusing on when to trip the reactor breaker only or the line breaker for faults on the line or in the reactor. It also discusses issues with delayed current zero crossing on shunt compensated lines with a higher degree of compensation. The presence of the series capacitor on a line and the line shunt capacitance generates subsynchronous oscillations with a shunt reactors which has an impact on the sensitive protection functions. These sensitive functions relying on the sequence parameters based on system nominal frequency and the paper points out to the methods to prevent overtripping. Paper discusses conventional protection schemes such as overcurrent, differential, directional overcurrent, overvoltage protection, focusing on the specific design features provided in various modern relay designs and typical ranges for setting these functions considering these design features. In addition to the protection itself, paper discusses peculiarities of the CT performance due to high X/R of shunt reactors.
Paper also highlights latest protection techniques for turn-to-turn faults and provide setting examples with discussions as well discusses few utility events, covered in the guide.