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2.13
Forward Active Power Supervision (ANSI 32F)
The machine protection 7UM61 includes an active power supervision which monitors
whether the active power undershoots one set value or overshoots a separate second
set value. Each of these functions can initiate different control functions.
When, for example, with generators operating in parallel, the active power output of
one machine becomes so small that other generators could take over this power, then
it is often appropriate to shut down the lightly loaded machine. The criterion in this
case is that the "forwards" power supplied into the network falls below a certain value.
In many applications it can be desirable to issue a control signal if the active power
output rises above a certain value.
When a fault in a utility network is not cleared within a critical time, the utility network
and should be split or for example, an industrial network decoupled from it. As criteria
for decoupling, in addition to power flow direction, are undervoltage, overcurrent and
frequency. As a result, the 7UM61 can also be used for network decoupling.
2.13.1 Function Description
Active Power Mea-
Depending on the application either slow high-precision measurement (averaging 16
suring
cycles) or high-speed measurement (without averaging) may be selected. High-speed
measurement is particularly suitable for network de-coupling.
The device calculates the active power from the positive sequence systems of the
generator currents and voltages. The computed value is compared with the set values.
Each of the forward active power stages can be blocked individually via binary inputs.
In addition the entire active power monitoring can be blocked per binary input.
The following figure shows the logic diagram for forward active power supervision.
Figure 2-26
7UM61 Manual
C53000-G1176-C127-3
2.13 Forward Active Power Supervision (ANSI 32F)
Logic Diagram of the Forward Active Power Supervision
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