Protection and Control System Impacts from The Digital World

Gone are the days of the easy electro-mechanical relay with out firmware and conversation interfaces. The reality exists that protection and manage systems have changed significantly within the past decade and will hold to change with generation advancements. The virtual global has impacted the protection machine from the introduction of microprocessor based totally relays within the 1980s to safety relays with conversation interfaces inside the 1990s. Today’s superior virtual defensive relays utilize high speed verbal exchange to replace copper wires for inter-bay manipulate, protection interlocking and even breaker journey and closing. Modern sensor technology additionally allows World for the digitization and analog acquisition in the switchyard replacing unsafe inductive CT and PT circuits with manner bus communications. The Digital World has introduced many benefits but additionally introduces challenges. This paper will cognizance on the effect of the safety and control system as a result of microprocessor relay creation inside the 1990s. It will speak key troubles the protection and manage engineer has encountered inside the beyond and could face with the deployment of the advanced defensive relay. Key regions discussed could be overall performance and blessings along with the digitization and transfer characteristic of Nonconventional Instrument Transformers, security threats and best practices for the protection machine, fleet management in the age of NERC PRC/CIP policies and overall performance consideration to achieve high availability of the safety and manipulate system. As nicely the paper will cope with some safety troubles such as; when you consider that fiber optic current sensor structures haven’t any iron, and no CT saturation, the differential relay want not have multiple World slopes to account for CT overall performance, only a minimum select up for that reason World growing the sensitivity numerous fold. The educational benefits to understanding these impacts is paramount inside the adoption and embracing of modern-day tracking and control structures. Understanding the requirements to enhance the overall performance of the substation automation safety and manage systems is the intention to create the knowledgeable selection maker embracing these improvements in new technology which from a reliability attitude can significantly improve the overall power system overall performance.

The Digital Systems

In the virtual system, sampled analog values are communicated according IEC 61850-9-2 from merging devices or non-conventional device transformers (NCITs) to the protection World and manipulate IEDs and ride commands are sent as IEC 61850 GOOSE messages to the circuit breaker interfaces. By this, the communique gadget becomes a vital part within the fault clearance chain affecting the entire fault clearance time of the safety system.


Fault Clearance times of Digital Systems

When approaching to apply NCITs and Ethernet conversation to switch mission crucial analog and binary information for safety functions, the tripping speed does now not depend anymore most effective on the protection IED and tripping relays. In virtual systems, the fault clearance time is relying at the overall performance of all concerned electronic components like NCITs, merging units, safety IEDs and breaker IEDs, as well as on the layout of the method bus verbal exchange machine. The expectation at the virtual system is that they fulfill today’s specifications and regulations concerning fault clearance time and they perform at the least as right as today’s safety systems. A normal figure for fault clearance times under normal conditions (with out failures in safety machine or circuit breaker) is 4 electricity cycles. Two cycles are considered for the circuit breaker commencing with extinguishing of the arc and cycles are assumed for the protection system. These figures can be observed in international trendy like IEC 60834 and national regulations like NERC’s technical paper on protection system reliability or National Grid UK’s grid code. Figure Overview at the time finances from fault inception to fault clearance with normal operating instances of the safety gadget in a traditional gadget without NCITs and method bus communication.

Overall operating time for a teleprotection
Overall operating time for a teleprotection

Moving to the digital world, Figure depicts the fault clearance chain from NCIT through protection relay to breaker IED and circuit breaker.

protection IED
protection IED

Two of the times inside the above determine are described and categorized by means of international requirements. The “processing delay time“ of NCITs and merging units is defined in IEC 60044-eight as rated put off time, which shall not exceed 3ms for safety applications. The “Transfer time” definition is part of IEC 61850-5. For both, sampled values and ride commands sent thru GOOSE, the best switch time overall performance magnificence applies, which shall be 3ms or less. The switch time is the sum of the times required with the aid of the stack of the sending tool, the stack of the receiving tool and the communique gadget. According to IEC 61850-10 and IEC 61850-90-4, the 3ms are assumed to be split 80% to the processing instances within the IED stacks (2.4ms) and the last 20% (0.6ms) for the communication network.

The Digital World Opens up Cyber Threats

Cyber security creates fear in our enterprise as citing NERC/CIP compliance can lead to the incorrect behavior. The statistics available in our utility systems is essential for advancing machine performance, proactive manage and advanced operations and maintenance. Cyber safety requirements offer the framework and requirements either toward compliance or technical solutions. The educational benefits to understanding these requirements is paramount inside the adoption and embracing cyber safety as a key enabler to our contemporary tracking and manipulate systems. The reality exists that substation automation, protection and manipulate systems have modified significantly within the beyond decade and will continue to alternate with generation advancements. Systems have grow to be extra interconnected and provide stop customers with much greater data to allow for better reliability and more degrees of manage. Interoperability between distinct vendor merchandise and systems has been completed with the aid of growing products and solutions primarily based on open standards and through leveraging commercial era like fashionable Ethernet technology. This alternate in technology has now not handiest brought big benefits from an operational point of view as discussed within the previous sections, it also permits substation automation, safety and control structures to deal with cyber security troubles just like different traditional, business enterprise structures which have been facing the same industry challenges for years.

Tightly integrating the control gadget components and allowing inter-linked manage systems with the external structures no longer simplest lets in for extra and faster facts exchange, but, it additionally gives entry points for hackers and will increase the need to defend towards cyber-attacks. Using Ethernet and TCP/IP primarily based communications not simplest make systems extra interoperable, however additionally opened the door for trojans, worms, viruses and Internet based totally attacks, etc. The need for secure substation automation protection and control structures as well as the entire software Information Technology infrastructure is being pushed in many markets through regulations to make certain country wide safety because of the potential effect that a coordinated cyber-assault on the electric application control device ought to have on extensive scale outages. The key to any successful safety gadget is deploying Defense-in-depth approach as proven in above figure.

Threat fashions are constantly changing, the terrible guys are getting smarter and the tracking and control of the overall IT structures is paramount to keep the electricity system manipulate equipment safe and secure. In addition to government pushed efforts the multiplied importance of cyber protection for strength systems has additionally lead to numerous standard bodies and working organizations taking up the challenging topic. The focus, level of element and maturity of these efforts are quite broad. At the moment 5 initiatives appear to be maximum advanced, which we will talk in the following paragraphs and should be covered for your application common cyber protection coverage and practices.

Benefits of Digital Substation

A fully digital substation is smaller, greater reliable, has a reduced life-cycle cost and is simpler to hold and expand than an analog one. It gives accelerated protection and is extra green than its analog equivalent. Not each substation needs to be catapulted into a wholesale virtual global – it depends at the substation size and type, and whether it is a new station or a retrofit of the secondary machine. Different techniques and answers are required. Flexible answers allow utilities to set their own tempo on their manner towards the virtual substation.

• Increased device availability by means of replacing of electromechanical, static or old fashioned digital secondary system with cutting-edge numerical gadgets bundled to a real-time verbal exchange community and connected to a better stage system along with a substation automation system or SCADA, lets in continuous tracking of all connected secondary equipment.

• Increased gadget and personnel safety making use of remote manipulate blended with authority and rulebased access and faraway testing, lets in elevated device protection and security. Personnel safety is increased since extra tests may be executed with out placing the test employees close to number one gadget or with out the threat of inadvertently opening current transformer (CT) circuits.

• Increased capability with a fully allotted architecture coupled with un-restricted verbal exchange and system capability permits the gadget to feature new functions easily with zero or minimal outage time, giving the consumer additional benefit with admire to secure and secure machine.

• Interoperability via deployment of IEC 61850 compliant answers, interoperability with reference to communications with other manufacturer’s device can be achieved. The advantage is IEDs from exceptional suppliers can be mixed on the same bus with out situation for verbal exchange incompatibilities.

Technology has changed appreciably from over the past 30 years and could hold increase enabling greater advantages from The Digital World. The early adoption of microprocessor relays started out the generation into The Digital World. Along with their large advantages, they additionally added our global to software and communicating devices to the area of Cyber Threats in our converting surroundings. The advent of the IEC 61850 station and technique bus standards for substations has provided a platform that each one manufactures can develop upon to achieve the general intention of interoperability. John Burger’s visionary ideas are being found out with the technology to be had today. In addition to the interoperability benefits, footprint of primary switchgear discount the use of sensors (NCIT) replacing traditional measuring transformers and breaker controls lets in a far more secure work environment and a large discount of cabling via going from quite a few copper cables to 3 fiber optic verbal exchange cables. As for the challenges presented by the cyber threats, the industry need to embrace present day device competencies to deter, postpone and come across the terrible guys. Let us now not forget about that the multifunction relay is these days the source of information that could enable better degree systems to be proactive within the basic energy machine stability. Most importantly, the “R” in NERC way reliability so while CIP standards would possibly drive companies to shutdown conversation access to the substation records, it is so crucial that the substation facts be handy to better level structures.


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