Breaker and internal busbar faults are generally accompanied by high-level short circuit currents and thereafter create very dangerous conditions for power system stability. That is why very fast tripping is absolutely required for busbar protection as well as its selectivity for detection of internal and external faults.
The TOR 300 DPB devices provide reliable busbar differential protection for HV, EHV and UHV substations. The IED provides three (single-phase) differential zones and operates as low impedance centralized differential protection. Each differential zone within TOR 300 DPB consists of main differential protection function, sensitive current unit and differential current function for CT circuit supervision. Fine numerical equalization of the bay CTs rated currents is implemented. Differential protection follows automatically the connections of different bays to a certain busbar section and this way ensures dynamic bay selection within a certain differential zone. Sensitive current units are designed to automatically increase the sensitivity of busbar protection during busbar autoreclosing cycle, and for consecutive tripping of bays with smaller fault current. Sensitive current units may also be used for tripping the bay at switch-onto fault conditions. CT circuit supervision prevents unnecessary operation of busbar protection for different faults in CT secondary circuits.
Differential protection for busbars with more than 8 bays is implemented on per phase basis in each TOR 300 DPB device Each IED provides selective this way protection of one phase within sectionalized (two) busbar systems. It comprises for this purpose three single-phase differential zones: one check-zone and selective zones for the 1st and the second busbar section:
One TOR 300 DPB device can provide three-phase restrained busbar differential protection and protect all three phases of small busbar up to 4 bays (TOR 300 DPB in 1/2 of 19” case) or busbar with up to 8 bays (TOR 300 DPB in 3/4 of 19” case).
Development of the centralized PAC technologies for substations is one of the most prospective directions for their further improvement. The centralized structure of PAC functionality provides high flexibility of their structure and amount of the real time signals, which can be processed in different algorithms. In addition to this, centralized PAC systems within substations allow obtaining high economic effects on capital investments and reduction of operating costs.
Relematika can provide two solutions for the centralized PAC system for down-up HV /MV substations:
Main functions (within one TOR 300 IED)
Examples of centralized PAC implementation
Substations should be provided with a full interlocking scheme to ensure that all disconnectors, fixed earthing switches (or other interlocked earthing devices) and, where required, circuit-breakers are operated in the correct sequence so that personnel do not endanger themselves and/or the integrity transmission against incorrect or inadvertent operation of equipment. Where necessary, such interlocking shall also be extended to cover limitation of access to areas where there is a risk that normal safety clearances may be infringed.
Interlocking schemes shall cover the following conditions:
Relematika has different solutions to ensure reliable interlocking systems.
Local interlocking scheme is designed by using TOR 300 bay controller for a single bay unit. Position of disconnectors, earthing switches and breakers are transferred to the IED by their auxiliary contacts over copper cables. Two contacts are used within each primary unit - an open and a close contact to ensure the true position of switches. Interlocking logic is created by using the PCAP software and loaded into the bay controller. Data exchange between IEDs within substation (if necessary) is performed by using UniSCADA communication networks and EC 61850 standard (GOOSE) messages.
Distributed interlocking scheme use separate bay controllers as a DMU (acquisition system) thereafter present information transferred to central unit (controller) or to SCADA by fiber optic or cooper cables. Interlocking logic is performed into the central controller or as one of applications of UniSCADA.Centralized interlocking scheme is