Protection Coordination,
Arc Flashand Disturbance Analysis

Overview

APS provides specialist engineering studies for protection coordination, relay setting verification and disturbance analysis across transmission, distribution, renewable generation, BESS, industrial, data centre and private network installations.Protection systems are required to operate correctly under a wide range of credible network conditions, including changing fault levels, weak-grid operation, inverter-based generation, transformer energisation, large motor starting, parallel feeders, cable-dominated networks, embedded generation and complex industrial load behaviour.In these networks, protection settings should not be treated as a simple relay configuration exercise. A structured engineering assessment is required to confirm that each protection device operates with suitable sensitivity, selectivity, speed, security, dependability and stability under the expected fault and operating conditions.APS supports protection studies from early design and protection philosophy review through to detailed relay setting preparation, independent setting review, commissioning support, protection audit and post-event investigation. The study may include short-circuit assessment, relay grading, time-current coordination, overcurrent and earth-fault protection, directional protection, distance protection, transformer protection, generator protection, motor protection, feeder protection, busbar protection, breaker failure protection and interface protection for grid-connected installations.
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Studies can be carried out using industry-recognised tools such as DIgSILENT PowerFactory, ETAP, EMTP®, PSCAD™/EMTDC™ and manufacturer relay configuration software. This allows protection performance to be assessed not only using conventional short-circuit studies, but also under dynamic and transient conditions where CT saturation, CVT response, DC offset, transformer inrush, harmonics, converter control response, fault resistance, weak infeed conditions, power swings and protection logic may influence relay operation.APS also provides disturbance and event analysis services based on relay disturbance records, COMTRADE files, event logs, fault records, breaker operation records and relay setting files. This service is particularly useful after unexpected tripping, delayed clearance, nuisance operation, breaker failure, unexplained outages or suspected protection maloperation.By combining recorded waveforms, relay event reports, protection settings, network modelling and engineering judgement, APS can help identify the likely sequence of events, assess whether the protection system operated correctly and recommend practical corrective actions.

Disturbance and Event Analysis

Disturbance and event analysis is required when the actual behaviour of the power system or protection scheme needs to be understood after a fault, trip, outage or abnormal operating condition.APS reviews relay disturbance records, COMTRADE files, event logs, setting files, breaker operation records and recorded voltage/current waveforms to identify the likely sequence of events and determine whether the protection system operated as expected.Where required, events can be reconstructed using DIgSILENT PowerFactory, EMTP® or PSCAD™/EMTDC™ to support root-cause analysis, relay performance verification and corrective action planning

• Analysis of COMTRADE files recorded by protection relays More info
• Fault and event investigation using SIGRA and similar tools More info
• Review of relay event reports and disturbance records More info
• Analysis of voltage and current waveforms during faults and trips More info
• Identification of fault type, fault location and likely fault inception sequence More info
• Assessment of relay pickup, trip timing and protection element operation More info
• Review of breaker opening time and fault-clearing sequence More info
• Investigation of unwanted tripping, delayed tripping and failure to trip More info
• Assessment of protection maloperation, miscoordination and nuisance operation More info
• Comparison of recorded events against relay settings and expected behaviour More info
• Reconstruction of events using PowerFactory, EMTP® or PSCAD™/EMTDC™ where required More info
• EMT-based analysis of complex protection events in converter-rich networks More info
• Investigation of CT saturation, DC offset, inrush, harmonics and transient effects More info
• Root-cause analysis and recommendation of corrective actions More info
• Preparation of technical event investigation reports for asset owners, EPCs, developers, utilities and insurers More info

Typical Applications

These studies are suitable for projects where protection performance, relay coordination, fault clearance time, backup operation, grid-code compliance or post-event behaviour must be technically justified.

• High-voltage substations
• Transmission and distribution networks
• Solar farms and wind farms
• Battery energy storage systems
• Generator connections
• Data centres and mission-critical facilities
• Industrial plants and manufacturing sites
• Oil and gas facilities
• Mining and heavy-load facilities
• Water treatment and pumping stations
• Large private MV networks
• Grid-connected generation projects
• Sites affected by nuisance tripping or unexplained outages
• Projects requiring independent protection setting review
• Existing installations requiring protection audit or selectivity review

Technical Value

The objective of the study is to provide a technically justified assessment of protection performance before incorrect settings, weak coordination or protection maloperation become safety, compliance or operational issues.APS combines short-circuit studies, relay setting calculations, protection coordination review, manufacturer relay documentation, disturbance record analysis and advanced simulation to help clients understand how the protection system will operate under credible fault and network conditions.The assessment supports early design decisions, relay setting preparation, protection philosophy development, commissioning verification, grid-code compliance, fault investigation, protection audit and corrective action planning.By combining RMS and EMT-based simulation, relay setting review, COMTRADE analysis, event reconstruction and practical protection engineering judgement, APS helps clients improve system reliability, reduce outage risk, avoid unnecessary disconnection, support safe fault clearance and demonstrate that protection coordination requirements have been properly considered.