Simon Richards

Protection of Double Circuit Transmission Lines

This paper describes different cases of parallel transmission lines and analyzes some well known application problems associated with their protection. Distance protection performance problems are in the focus due to the fact that they are the most commonly used protection type for parallel transmission lines. The behavior of ground overcurrent protection on double circuit applications is also discussed in the paper. Finally, some advanced features of communications assisted schemes, non-communications protection schemes and fault location for double circuit lines are discussed

Integrated scheme for high impedance fault detection in MV distribution system

High impedance fault (HIF) in MV distribution with restricted fault current cannot be detected and cleared by conventional overcurrent relays. HIF exposes great hazard for personal safety and property security. In this paper, an integrated scheme utilizing different features of HIF is presented. Various documented field data has been investigated and summarized to get the most distinctive features of HIF. Based on these features, a simulation model using arc thermal equation and random factor has been developed. The integrated scheme investigates into different scopes of the fault features ranging from transient high frequency, harmonic distortion to fundamental intermittent. EMTP (Electromagnetic Transients Program) simulation results show that the integrated scheme can detect most HIFs, and discriminate HIF from other interference scenarios such as CT saturation, load nonlinearity and capacity transients. Therefore, this scheme achieves a better result with reliability and security.

Advanced distance protection applications fot dynamic loading and out-of step condition

Distance relays have been successfully used for many years as the most common type of protection of transmission lines. The development of electromechanical and solid state relays with mho characteristics can be considered as an important factor in the wide spread acceptance of this type of protection at different voltage levels all over the world. Zone 1 of distance relays is used to provide primary highspeed protection of a significant portion of the transmission line. Zone 2 is used to cover the rest of the protected line and provide some backup for the remote end bus. Zone 3 is the backup protection for all the lines connected to the remote end bus. The experience from the North American blackout in August 2003, as well as the recent European disturbance in November 2006 demonstrated the importance that the behavior of many distance relays had during the dynamic loading at different stages of the disturbance and the out-of-step conditions that followed in some areas The implementation of distance relays requires understanding of its operating principles, as well as the factors that affect the performance of the device under different abnormal conditions. The paper analyzes different methods for resolving the load encroachment of the apparent impedance into the distance characteristic as a result of dynamic loading and the detection of faults at that time. Another important issue is the operation of distance relays during stable or unstable out-of-step conditions. Depending on the location of the distance relays in the system and the type of event the relays may use blocking of the selected distance elements or tripping if separation is required.

Simplifying the configuration of multifunctional protection relays

The paper analyzes the functionality of state-of-the-art protection relays and presents solutions that simplify their configuration. Visibility control and graphical user interface are some of the tools that can help reduce engineering time and probability for costly errors. Some features that automatically calculate relay settings are also described in the paper. IEC 61850 related configuration settings are also discussed.

Smart substation for the French power grid

The paper describes a smart substation project launched two years ago, as part of the French governments plan “investments for the future”. This project is named “Poste Intelligent” within RTE (Smart Substation, in English), and aims to test in real conditions the latest technological developments for both primary and secondary equipment using the second edition of the IEC 61850 standard and new information and communication technologies in a fully interoperable solution. For the first time in France, the substation is designed like an autonomous entity, with adaptive solutions using horizontal inter-substation communications, in addition to the traditional hierarchical concept of “substation to SCADA”.

High-speed directional comparison protection of transmission lines

Improvements of system stability and reduction in the effects of shunt type faults in transmission and bulk systems on sensitive industrial loads can be achieved through the development of protection relays with sub-cycle operating times for faults anywhere on the transmission line. State-of-the-art communications methods and advanced algorithms allow the implementation of such solutions. The paper discusses in detail a directional comparison protection system based on superimposed components directional detection. A new relay-to-relay communications protocol meets the requirements of different schemes and at the same time ensures fast operating times over different communications channels.