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ACMart
Asset Condition Monitoring
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ACMart is a complex Asset Condition Monitoring system to address the needs of Transmission System Operators (TSOs). ACMart increases reliability and safety of the transmission network as well as reducing its maintenance and replacement costs.
ACMart automatically monitors and evaluates the condition of high voltage (HV) TSO equipment. ACMart covers almost all HV equipment in the transmission network. With the exception of power transformers, the system does not require additional installations of hardware sensors on every unit of the equipment.
ACMart works fully in line with the latest trends of smart transmission networks and CIGRE initiatives. The ACMart software package components are shown in the following picture.
ACMart automatically monitors and evaluates the condition of high voltage (HV) TSO equipment. ACMart covers almost all HV equipment in the transmission network. With the exception of power transformers, the system does not require additional installations of hardware sensors on every unit of the equipment.
ACMart works fully in line with the latest trends of smart transmission networks and CIGRE initiatives. The ACMart software package components are shown in the following picture.
Fig. 1 – ACMart Software Package
ACMart Platform
ACMart Platform is the basic user working environment. It provides, for example, an overview of the monitored equipment, its details, its ranking according to indexes – importance, health, and risk and generates many different reports, e.g. specific overhead lines, transformers, and specific substation bays availability evaluation during the year. The risk indexes support decision-making concerning repairs, maintenance, replacements and reconstructions by scoring an assessment of actual individual equipment service conditions.
ACMart Platform also shows the data from network monitoring devices (from substation control systems in the dispatch centre database, from relays - event recorders) and from the ERP system (equipment lists, maintenance planning, and maintenance result inventory database).
Fig. 2 – System Overview
ACMart Extensions
ACMart Records Viewer
Use Records Viewer enables the examination of details of events recorded by fault recorders.
ACMart SAP Connector
Automatic usage of data from SAP ERP (equipment inventory, equipment maintenance planning schedule, and results of performed maintenance and diagnostic measurements, equipment failure reports etc.). This extension may reduce the number of SAP licenses needed for the maintenance department.
ACMart EUCLID Connector
EUCLID Connector obtains evaluation data from the European Cooperation for Lightning Detection (EUCLID) system providing information about the overhead line in whose vicinity a lightning strike was detected and the many details of such a strike. This information is subsequently used to evaluate some of the events recorded by ACMart Plug-ins.
ACMart DGA Connector
Connector to the external IT system evaluating data from dissolved gas analysis in oil samples from transformers.
ACMart Maintenance Economy
The Maintenance Economy extension allows modeling and comparison of different scenarios in order to optimize maintenance plans.
ACMart Plug-ins
Each plug-in focuses on an individual issue in the network and its function is to monitor a specific event or value type.
RESTRIKE
This plug-in identifies non-standard behavior of circuit breakers in the HV network. It decides whether there was a re-strike in the circuit breaker during its opening, and, if so, whether it was a simple or multiple re-strike.
CVTFAIL
Recognizes of changed capacity of Capacitance Voltage Transformer (CVT) - broken capacitors inside CVT.
CBTIME
Recognizes of time delay discrepancy among circuit breaker (CB) poles. Time shifts that are longer than the limit indicate problems in the transmission path, in the signal operating in the drive, or in the breaking chamber of the CB.
SATUR
Recognizes of oversaturated current transformers (CT) cores. For the proper functioning of protections, it is important that the CTs measure short circuit currents accurately. When a CT core is oversaturated, it may result in protection malfunctions.
CBCURRENT
Monitors the number and value of switch-off currents by circuit breaker (CB) – automatic calculation of the cumulative number of CO cycles (ΣCO) and load by switch-off currents (ΣI2t) for triggering major maintenance of circuit breakers. Each manufacturer provides characteristics of its circuit breaker and the limit value of the ΣI2t; if this limit is exceeded, time-consuming and expensive maintenance must be carried out. Therefore, proper monitoring can be highly beneficial.
SHORTCIRC
This plug-in is used to calculate the cumulative load by large currents on all power system elements that come close to the short circuit. During a short circuit, insulating properties of the device may degrade. SHORTCIRC detects not only the through-load short circuit currents, but also closing currents of transformers.
ASYNCHRON
Finding and evaluating records of incorrect phasing, i.e. asynchronous switching to an angle different by more than 18° (1 ms), or with different power plant and network frequencis. Incorrect phasing subjects circuit breakers to high currents, resulting in major stress and accelerated ageing.
OVERVOLT
Reveals overvoltage of various equipment. This can occur due to poor configuration of network elements or due to fault events. Most occurrences of temporary overvoltage were recorded during a partial collapse of the electricity system. Temporary overvoltage may cause irreversible degradation of surge arresters and can cause degradation of insulation of other devices.
FERO
Reveals occurrences of resonance and ferroresonance. These events result in overvoltage stress of instrument transformers and voltage transformers, accelerating the ageing of their insulation. The undamped ferroresonance 50 Hz can even lead to destruction of the transformer and significant damage. Ferroresonance may also disable the control in the case of ferroresonance in a phase whose voltage is used for phasing.
INRUSH
Evaluation of power transformer loadings by inrush currents. Device status can be assessed based on evolution of these parameters. Moreover, it is possible to detect excessive load of the power transformer directly.
IGNI
Recognition of circuit breaker (CB) pre-ignitions during closing. It differentiates between the random early ignition on healthy CBs (the time between the final closing and the early ignitions is no more than about 1 to 2ms) and the more serious cases ( the time is longer than 4 ms, pre-ignitions often come in series, occurring often or at almost every closing, etc.) that indicate a poor state of CB.
Fig. 4 – Circuit Breaker Current
Success Stories
ČEPS (Czech national TSO) is operating 171 pieces of 420 kV and 245 kV single phase capacitive voltage transformers (CVT). They were manufactured between the years 1991 and 2000. So far, the ACMart system (CVTFAIL) has discovered 8 units with broken capacitive layers. The units were replaced before the problem developed into a major failure. Broken capacitors were confirmed when the units were opened. Estimated avoided damages exceed EUR 500,000.
ČEPS is operating 190 pieces of 420 kV and 94 pieces of 245 kV three-phase circuit breakers. The ACMart system (RESTRIKE) has discovered 10 poles having re-strikes during no-load switching operations. The 6 poles in which the re-strikes appeared more than twice were opened and repaired. There were visible traces of arcs, in places where normally no arc should be present, found in open interrupter units. The RESTRIKE plug-in replaced offline measuring, saving more than EUR 100,000 each year.
ČEPS is operating 115 fields in 420 kV substations in which there are circuit breakers installed with grading capacitors and inductive voltage transformers. Under certain conditions, their combination can generate ferroresonance overvoltage. The ACMart system (FERO) has discovered11 fields with the occurrence of sub harmonic (16.67 Hz) ferroresonance with overvoltage exceeding 1.p.u. in some cases. This type of ferroresonance can contribute to ageing of the voltage transformer insulation. The proper measures for changing field configuration or changing the sequence of switching operations were adopted immediately. The avoided damage is estimated to be more than EUR 200,000.
ČEPS is operating 190 pieces of 420 kV and 94 pieces of 245 kV three-phase circuit breakers. The ACMart system (RESTRIKE) has discovered 10 poles having re-strikes during no-load switching operations. The 6 poles in which the re-strikes appeared more than twice were opened and repaired. There were visible traces of arcs, in places where normally no arc should be present, found in open interrupter units. The RESTRIKE plug-in replaced offline measuring, saving more than EUR 100,000 each year.
ČEPS is operating 115 fields in 420 kV substations in which there are circuit breakers installed with grading capacitors and inductive voltage transformers. Under certain conditions, their combination can generate ferroresonance overvoltage. The ACMart system (FERO) has discovered11 fields with the occurrence of sub harmonic (16.67 Hz) ferroresonance with overvoltage exceeding 1.p.u. in some cases. This type of ferroresonance can contribute to ageing of the voltage transformer insulation. The proper measures for changing field configuration or changing the sequence of switching operations were adopted immediately. The avoided damage is estimated to be more than EUR 200,000.
References
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ČEPS, a.s.
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