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LINE SECTIONALIZING USING A PLC AND ABB PROTECTIVE RELAY
•
Real Time Switching is based on instantaneous decisions made by the
microprocessor based IEDs.
As illustrated in Figure 1, the feeder and substation 2 are located a great distance away from the main
PLC. Inexpensive radio scatter modems are used to allow communication between the PLC which has
the RTU based functionality and logic imbedded within it and the remote IEDs.
Line Sectionalizing Explained
This application note is intended to illustrate the method of obtaining information from the IED's through
the Modbus and Modbus Plus interfaces. Each one of the nodes, PLC, IED and HMI operate in concert
as follows:
1. The PLC reads/writes/calculates information obtained from the TPU2000R via the Modbus
Plus network. Data gathered from the TPU2000R is:
•
Breaker Status (52a, 52b) is read
•
Cumulative Watts, Vars, 3 Phase Power, Amps, Volts, Watts, Var values are read.
•
Calculation of the combined loading is performed when the Substation Location 1 is
feeding the lines at Location 3 (PCD2000).
2. The PLC reads/writes information between itself and the DPU2000R. Data gathered by the
PLC is:
•
Breaker Status (52a, 52b) is read.
•
Cumulative Watts (per phase and 3 phase), Vars (per phase and 3 phase), Amps,
Volts, frequency values are read.
•
Calculation of the combined loading is performed when the Substation Location 2 is
feeding the lines at Location 3 (PCD2000).
•
Control Operation capabilities such as breaker trip and breaker close can be
completed automatically (via logical decisions made by the PLC) or manually (via an
operator at the HMI station).
3. The PLC reads/ writes information between itself and the PCD2000. Data gathered by the
PLC is:
•
Breaker Status (52a, 52b) is read.
•
Cumulative Watts (per phase and 3 phase), Vars (per phase and 3 phase), Amps,
Volts, frequency values are read.
•
Control Operation capabilities such as breaker trip and breaker close can be
completed automatically (via logical decisions made by the PLC) or manually (via an
operator at the HMI station).
4. The MAGELIS HMI displays the data values held in the PLC. In this installation, the PLC
acts as a data concentrator and arbitrator for the logic operations. The MAGELIS HMI can
disable the automatic restoration functions preprogrammed in the PLC. With the PLC placed
in manual control mode, the operator viewing the data on the MAGELIS screen can perform
manual restoration since visualization of each breaker and all feeder metering values are
displayed on the screen.
There are two modes of operation, MANUAL and AUTOMATIC restoration.
AUTOMATIC mode, line restoration is performed by the PLC without any operator intervention.
AUTOMATIC MODE operation occurs as such:
1. The breakers at Substation Location 1 and Feeder Location 3 are closed. The breaker at
Substation Location 2 is open. In this example, the feed from the TPU2000R is providing
supply to the feeder at location 3.
calculating the average load required by Feeder Location 3.
2. On the event of a fault, the TPU2000R trips the breaker.
immediately (under 10 mS in this case) and immediately determines if sufficient reserve is
available at Substation Location 2 to supply Feeder Location 3.
The PLC is constantly reading metering values and
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With the system in
The PLC recognizes the trip
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