Ilia Voloh

Reviewing smart grid standards for protection, control, and monitoring applications

Two-way seamless communication is the key aspect of realizing the vision of smart grid. Currently, several smart grid standardization efforts are underway in US and Europe. National Institute of Standard and Technology (NIST) has prioritized several process of standardization and harmonization of existing standards with the new developments. Power system protection, control and monitoring (PCM) are one of the most time critical applications for power utilities in the smart grid environment. This paper present review of available standards for PCM and discusses their applications and current developments. Moreover, the paper also highlights the challenges related to smart grid standardization in brief.

Rebirth of the phase comparison line protection principle

This paper presents a standard pilot phase comparison protective relaying scheme for transmission lines. It offers excellent sensitivity, very fast tripping, immunity to power swings, effective protection for long or short lines, and reduced need for setting calculations and settings maintenance. The performance is superior to that of pilot distance or directional comparison schemes. The proposed scheme meets the technical and management demands for protective relaying satisfying more stringent system security requirements.

Fault location, isolation, and service restoration (FLISR) technique using IEC 61850 GOOSE

Electric distribution utilities are paying more and more attention towards enhancement of end-user supply reliability and power quality. “Self-heal” nature of distribution network is gaining interest in the industry. With deployment of distribution automation applications, they can not only achieve these performance goals but also improve situational awareness, and reduce the financial penalties they incur due to system outages. Fault Location, Isolation and Service Restoration (FLISR) is one of the key distribution automation application, which can significantly reduce outage time to the end customers. At the same time, standardized automation system based on IEC 61850 is proliferating in the market. This paper proposes a fast FLISR algorithm using IEC 61850 based Generic Object Oriented Substation Event (GOOSE) technology. The challenges and possible solutions while commercially deploying such smart applications are discussed in further detail.

Detection of Incipient Faults in Underground Medium Voltage Cables

This paper presents an operational experience with incipient faults: it has been observed that 10 to 15% of cable faults are preceded by incipient faults. Practically all incipient faults become permanent faults in the period between a few seconds to few weeks. Incipient faults occurring in fast successions create considerable over-voltages and induce faults on other feeders. A method has been presented to detect incipient faults in a secure and reliable way. The method is secure by checking consistency of the load before and after the event, checking if the event is a single phase event, and checking for duration and consistency between the superimposed fault component and the ground current. The presented method has been implemented and tested using recorded field cases and on a digital simulator. Simplified variants of the method can be implemented by using programmability and flexibility of modern microprocessor based relays. Recommendations are given as to the trip vs alarm applications of the incipient cable fault detection functions. In many cases tripping on the first incipient fault is a prudent application.

The Power of IEC 61850: Bus-Transfer and Load-Shedding Applications

The new communications technology and the newly developed IEC61850[1] standard for generic object oriented substation events (GOOSE) bring many advantages to the industrial protection and control applications. Some of the applications benefiting the most are the ones associated with the bus transfer and the load shedding schemes, together with more beneficial communication-assisted schemes, like zone-interlocking, fast bus trip, arc-flash reduction, etc. Some Intelligent electronic devices (IEDs) are equipped with more than one high-speed Ethernet channel to transmit/receive hundreds of discrete and analog values. This offers two very big advantages over the copper wired IEDs: the first - a single pair of network cable either copper of fiber, can substitute a big number of standard copper wires, and the second - using two or more network channels provide very good data exchange redundancy and hence higher reliability. The savings on substituting a big number of copper wires by a communication media like Ethernet copper twisted pair cable, or a pair of fiber optic, can be easily calculated.

A review of smart grid standards for protection, control, and monitoring applications

Two-way seamless communication is the key aspect of realizing the vision of smart grid. Currently, several smart grid standardization efforts are underway in US and Europe. National Institute of Standard and Technology (NIST) has prioritized several process of standardization and harmonization of existing standards with the new developments. Power system protection, control and monitoring (PCM) are one of the most time critical applications for power utilities in the smart grid environment. This paper present review of available standards for PCM and discusses their applications and current developments. Moreover, the paper also highlights the challenges related to smart grid standardization in brief.

An adaptive HV transmission lines reclosing based on voltage pattern in the complex plane

Transient single-phase short circuits are the most common transmission line faults. The short circuit arc of a transient fault is usually self-extinguishing after opening the line circuit breakers. High-speed single-phase reclosing of transmission line can help to improve system stability. Employing a pre-set reclosing interval may pose problem if the time interval is not sufficient to fully deionize the fault arc. It is desirable to have adaptive reclosing interval and fast detection of arc extinction, which could facilitate successful high-speed reclosing of transmission line and bring benefit to the system stability. A new adaptive reclosing algorithm is proposed in this paper. It uses the pattern of the faulted phase voltage in the complex plane to distinguish between transient and permanent faults and is also able to detect the time when the arc is extinguished. Theoretical analysis is provided to support the technique. In addition, the performance of the proposed technique is verified using a recorded field data from 765 kV transmission line and several cases simulated in EMTP including detailed arc and CVT modeling.

An innovative timestamp-based convolution integral method in synchrophasor estimation within digital relays

In recent years, phasor measurement units (PMU) and wide-area monitoring systems (WAMS) techniques have been widely used in power systems to perform various monitoring, control and protection functions. It is a growing requirement for digital protective relays to include synchrophasor measurement functionalities for the apparent economical benefits. Modern digital protective relays typically use variable sampling rate (frequency tracking) so as to reduce measurement errors and avoid undesired trips during system frequency variations. However, frequency estimation may experience some inaccuracies during various power system dynamics, and in turn, it will result in sampling time interval errors because of the frequency tracking mechanism in the relay, and then result in synchrophasor estimation errors. An innovative timestamp-based convolution integral method has been developed to accurately estimate synchrophasors within digital relays, in which tracking frequency errors virtually do not have impacts to the phasor estimations. This method can be used for either variable sampling rate (frequency tracking) or fixed sampling rate. It can accurately estimate synchrophasors even with artificial extreme inaccuracies in tracking frequency estimations. In this paper, the theoretical derivations of the said method, the impact of the tracking frequency errors to phasor estimations, digital filtering and various tests to meet IEEE C37.118 steady state and dynamic performance requirements are discussed.

CT saturation tolerance for 87L applications

This paper is exploring requirements for the line current differential function (87L) with regards to the tolerance to current transformer (CT) saturation. Typically, requirements provided by the manufacturers or standards are to eliminate CT saturation completely by proper sizing of CTs, which is not always practical.

Justifying pilot protection on transmission lines

This paper concerns the justification of the use of pilot protection on transmission lines.