Quality information

The data attribute q that is a mandatory attribute for nearly all common data classes and therefore can be expected to be there for most information exchange via IEC 61850 is a bit string of 11 bits.

Each of the bit has a meaning and purpose. This set of articles shall explain some of the bits.


Table 10 – Quality components attribute definition (IEC 61850-7-1:2011/A1:2020)

Name

Type

Description

Presents condition

validity

ValidityKind

Validity of the value, as condensed information for the client. In case this value is not 'good', some reasons may be found in the 'detailQual'.

M

detailQual

DetailQual

Describes some reasons in case 'validity' is not 'good'.

M

source

SourceKind

(default=process) Defines the source of a value. NOTE 1 Substitution may be done locally or via the communication services. In the second case, specific attributes with a FC=SV are used. NOTE 2 There are various means to clear a substitution. As an example, a substitution that was done following an invalid condition may be cleared automatically if the invalid condition is cleared. However, this is a local issue and therefore not within the scope of this standard.

M

test

BOOLEAN

(default=FALSE) If TRUE, the value is a test value. The processing of the test quality in the client shall be as described in IEC 61850-7-4. This bit shall be completely independent from the other bits within the quality descriptor.

M

operatorBlocked

BOOLEAN

(default=FALSE) If TRUE, further update of the value has been blocked by an operator. The value shall be the information that was acquired before blocking. If this flag is set, then the 'detailQual.oldData' shall also be set. The operator shall use the data attribute 'CDC.blkEna' to block the update of the value. NOTE Both an operator as well as an automatic function may freeze communication updating as well as input updating. In both cases, 'detailQual.oldData' will be set. If the blocking is done by an operator, then this flag is set additionally, and an operator activity is required to clear the condition. EXAMPLE An operator may freeze the update of an input, to save the old value before the auxiliary supply is switched off.

M

overflow

BOOLEAN

(default=FALSE) If TRUE, the value of the attribute to which the quality has been associated is beyond the capability of being represented properly (used for measurand information only). EXAMPLE A measured value may exceed the range that may be represented by the selected data type, for example the data type is a 16- bit unsigned integer and the value exceeds 65 535.

M

outOfRange

BOOLEAN

(default=FALSE) If TRUE, the attribute to which the quality has been associated is beyond a predefined range of values. The server shall decide if validity shall be set to invalid or questionable (used for measurand information only). EXAMPLE A measured value may exceed a predefined range, however the selected data type can still represent the value, for example the data type is a 16-bit unsigned integer, the predefined range is 0 to 40 000, if the value is between 40 001 and 65 535 it is considered to be out of range.

M

badReference

BOOLEAN

(default=FALSE) If TRUE, the value may not be a correct value due to a reference being out of calibration. The server shall decide if validity shall be set to invalid or questionable (used for measurand information and binary counter information only).

M

oscillatory

BOOLEAN

(default=FALSE) To prevent overloading of event driven communication channels, it is desirable to detect and suppress oscillating (fast changing) binary inputs. If a signal changes in a defined time twice in the same direction (from 0 to 1 or from 1 to 0), then it shall be defined as an oscillation and this attribute shall be set to TRUE. If a configured number of transient changes is detected, they shall be suppressed. In this time, the 'Quality.validity' shall be set to 'questionable'. If the signal is still in the oscillating state after the defined number of changes, the value shall be left in the state it was in when this flag was set. In this case, the 'Quality.validity' shall be changed from 'questionable' to 'invalid' and kept so as long as the signal is oscillating. If the configuration is such that all transient changes should be suppressed, the 'Quality.validity' shall be set immediately to 'invalid' and this flag to TRUE (used for status information only).

M

failure

BOOLEAN

(default=FALSE) If TRUE, a supervision function has detected an internal or external failure.

M

oldData

BOOLEAN

(default=FALSE) If TRUE, an update is not made during a specific time interval. The value may be an old value that may have changed in the meantime. This specific time interval may be defined by an allowed-age attribute. NOTE "Fail silent" errors, where the equipment stops sending data, will cause setting this flag to TRUE. In this case, the last received information was correct.

M

inconsistent

BOOLEAN

(default=FALSE) If TRUE, an evaluation function has detected an inconsistency.

M

inaccurate

BOOLEAN

(default=FALSE) If TRUE, the value does not meet the stated accuracy of the source. EXAMPLE The measured value of power factor may be noisy (inaccurate) when the current is very small.

M