Measurements - ABB Relion Technical Manual

1MRK 502 048-UUS A
Section 14
14.1
14.1.1
Technical manual
Monitoring

Measurements

Functionality
Measurement functions is used for power system measurement, supervision and reporting
to the local HMI, monitoring tool within PCM600 or to station level for example, via IEC
61850. The possibility to continuously monitor measured values of active power, reactive
power, currents, voltages, frequency, power factor etc. is vital for efficient production,
transmission and distribution of electrical energy. It provides to the system operator fast
and easy overview of the present status of the power system. Additionally, it can be used
during testing and commissioning of protection and control IEDs in order to verify proper
operation and connection of instrument transformers (CTs and VTs). During normal
service by periodic comparison of the measured value from the IED with other
independent meters the proper operation of the IED analog measurement chain can be
verified. Finally, it can be used to verify proper direction orientation for distance or
directional overcurrent protection function.
The available measured values of an IED are depending on the actual
hardware (TRM) and the logic configuration made in PCM600.
All measured values can be supervised with four settable limits that is, low-low limit, low
limit, high limit and high-high limit. A zero clamping reduction is also supported, that is,
the measured value below a settable limit is forced to zero which reduces the impact of
noise in the inputs. There are no interconnections regarding any settings or parameters,
neither between functions nor between signals within each function.
Zero clampings are handled by ZeroDb for each signal separately for each of the
functions. For example, the zero clamping of U12 is handled by VLZeroDB in VMMXU,
zero clamping of I1 is handled by ILZeroDb in CMMXU.
Dead-band supervision can be used to report measured signal value to station level when
change in measured value is above set threshold limit or time integral of all changes since
the last time value updating exceeds the threshold limit. Measure value can also be based
on periodic reporting.
The measurement function, CVMMXN, provides the following power system quantities:
Section 14
Monitoring
507