Reliability Overview
The reliability module provides the ability to induce events on a system and evaluate their impacts. The reliability module collects and outputs module-appropriate metrics to a log file for user evaluation. reliability is only an event-inducing and metrics-recording module and requires specific interfaces to different modules of interest. At this time, the only module interface that exists is with the powerflow module (see the Power Flow User Guide).
Overall settings
The reliability module has two module-level settings that a user can specify. These two settings influence all reliability-related items in the system, regardless of the module. The two parameters are maximum_event_length and report_event_log, which would be implemented as
module reliability {
maximum_event_length 300 s;
report_event_log TRUE;
}
The maximum_event_length specifies the maximum duration any object may be in a fault condition on the system. If a randomly-generated fault exceeds this time limit, it will be thresholded to the value of maximum_event_length. However, manual faulting scenarios do not check this limit, and can produce longer fault condition.
The report_event_log property defines whether the metrics object will include a list of induced events, or just the output statistics. If enabled, the output file will include when an event started, when it ended, the desired fault, the implemented fault, and some customer information.
Reliability Objects
There are two object within the reliability module. These two objects will interact with specific module classes to generate the events and record module-appropriate metrics.
Metrics
The metrics object collects and outputs any of the measurements associated with reliability in a specific module. The actual metrics are computed by module-specific objects, such as the power_metrics object in the powerflow module. The output file containing the event information and reliability calculations is output by the metrics object.
A minimal metrics object would be implemented as
object metrics {
name test_metrics;
module_metrics_object powermetrics;
metrics_of_interest "SAIFI,SAIDI";
customer_group "groupid=METEROBJS";
}
with an equivalent implementation of
object metrics {
name test_metrics;
module_metrics_object powermetrics;
metrics_of_interest "SAIFI,SAIDI";
customer_group "groupid=METEROBJS";
metric_interval 0 s;
report_interval 1 yr;
}
Metrics Parameters
| Property Name | Type | Unit | Description |
|---|---|---|---|
| report_file | char1024 | N/A | File name where the event log (if desired) and metric calculations are written. |
| customer_group | char1024 | N/A | Defines the criterion for an object to be considered a customer. Uses specifications similar to collector objects with class= and groupid= being valid keywords. |
| module_metrics_object | object | N/A | Link to the module-specific metrics device to compute reliability indices related to that module. An example would be the power_metrics object in the powerflow module. |
| metrics_of_interest | char1024 | N/A | Comma-separated list of metrics to output into the report_file. Values desired must be published by the module-specific metrics object. |
| metric_interval | double | seconds | Intermediate interval over which to calculate reliability indices. Interval metrics will be reset every metric_interval seconds. Simulation-long metric calculations are unaffected by this value. Defaults to 0 seconds, so intermediate values are not output. |
| report_interval | double | seconds | Time period between writes to the report_file, unless prompted to do so earlier by metric_interval. Drives the output of overall simulation-long metric calculations. Defaults to 1 year. |
Eventgen
The eventgen object creates events on objects in the GLM file to test the reliability of the system. Such induced events often produce a relevant result in the metrics object, or in some output of the system. The eventgen object allows both manually specified, deterministic events, or randomly-generated, stochastic events.
eventgen objects must be parented to an appropriate metrics object to function. This allows the reliability indices to be calculated appropriately when an event is induced.
The minimal setup required for a randomly-induced event would be
object eventgen {
name RandEvent;
parent MetricsObj;
target_group "class=line AND groupid=FAULTY";
fault_type "DLG-X";
}
which is equivalent to a fully specified version of
object eventgen {
name RandEvent;
parent MetricsObj;
target_group "class=line AND groupid=FAULTY";
fault_type "DLG-X";
failure_dist EXPONENTIAL;
restoration_dist PARETO;
failure_dist_param_1 3.858e-7;
failure_dist_param_2 0.0;
restoration_dist_param_1 1.0;
restoration_dist_param_2 1.0002778;
max_outage_length 432000 s;
max_simultaneous_faults -1;
}
A deterministic eventgen object can be specified as
object eventgen {
name DeterEvent;
parent MetricsObj;
fault_type "DLG-X";
manual_outages "nodeB,2000-01-01 5:00:00,2000-01-02 6:00:00";
}
Note that a deterministic evengen object ignores the limits specified in the module-level maximum_event_length parameter, as well as the max_outage_length and max_simultaneous_faults properties.
Eventgen external event mode
eventgen also has an "external event" mode where an event can be sent via JSON string, via something like HELICS. To support this approach, a typical eventgen object would look like:
object eventgen {
name ExternalSupported;
use_external_faults TRUE;
}
External events are sent to the external_fault_event field, and have a JSON syntax of:
"{
\"name\": \"fault1\",
\"type\": \"TLL\",
\"fault_object\": \"line12\"
}"
where the name field is a unique identifier for the fault event, type is the same as the powerflow types listed at the end of this wiki page, and fault_object is the GridLAB-D object to induce the event on. Note that the name is utilized as a unique identifier of this fault, so to turn the fault off, simply sending that name will be sufficnent. e.g.,:
"{\"name\":\fault1\"}"
Eventgen Parameters
| Property Name | Type | Unit | Description |
|---|---|---|---|
| target_group | char1024 | N/A | Defines the criterion for the objects to induce faults upon. Uses specifications similar to collector objects with class= and groupid= being valid keywords. Note that stochastically specified eventgen objects will induce faults on all objects in the target_group field independently, with only consideration for the max_simultaneous_faults field. This field must be empty for manual_outages to work. |
| fault_type | char1024 | N/A | Describes the type of faults/events to induce on the specified objects. This is specific to the module the faults/events are being induced upon, or the reliability metrics are measuring. |
| failure_dist | enumeration | N/A | Distribution type used to generate times to random "failure" event on the system. Valid distributions are UNIFORM, NORMAL, LOGNORMAL, BERNOULLI, PARETO, EXPONENTIAL, RAYLEIGH, WEIBULL, GAMMA, BETA, and TRIANGLE. |
| restoration_dist | enumeration | N/A | Distribution type used to determine time to restoration on faulted/evented objects. Valid distributions are UNIFORM, NORMAL, LOGNORMAL, BERNOULLI, PARETO, EXPONENTIAL, RAYLEIGH, WEIBULL, GAMMA, BETA, and TRIANGLE. |
| failure_dist_param_1 | double | Varies | Parameter 1 for the distribution selected in failure_dist. Specifies the following for the distributions listed:
|
| failure_dist_param_2 | double | Varies | Parameter 2 for the distribution selected in failure_dist. If a distribution is not listed below, it does not need the second parameter. Specifies the following for the distributions listed:
|
| restoration_dist_param_1 | double | Varies | Parameter 1 for the distribution selected in restoration_dist. Specifies the following for the distributions listed:
|
| restoration_dist_param_2 | double | Varies | Parameter 2 for the distribution selected in restoration_dist. If a distribution is not listed below, it does not need the second parameter. Specifies the following for the distributions listed:
|
| manual_outages | char1024 | N/A | Manual input describing which object to fault, when to fault it, and when to restore it. In the syntax above, nodeB,2000-01-01 5:00:00,2000-01-01 6:00:00 would fault the object nodeB from 5 AM on January 1, 2000 to 6 AM on January 2, 2000. All times must follow the yyyy-mm-dd HH:MM:SS format. The fault induced is determined by the fault_type field. target_group must be empty for this field and implementation type to be considered. Subsequent faults may be specified in the same format (name, time start, time end). |
| max_outage_length | double | seconds | Defines the maximum time an object is allowed be out of service after faulted/evented. Serves as an upper limit to the value produced by the restoration_dist function. This parameter is ignored when a fault is specifed by the manual_outages field. |
| max_simultaneous_faults | double | N/A | Defines the maximum number of faults a particular eventgen object can create at once. If more faults are requested by the fault_dist property, they will be ignored. This parameter is ignored when a fault is specified by the manual_outages field. |
| use_external_faults | bool | N/A | If set to true, expects externally-defined events to come through the external_fault_event field in the JSON syntax noted above. |
| external_fault_event | char1024 | N/A | Input field for externally-defined/populated events. Must be in the JSON format described in Eventgen external event mode |
Powerflow implementation
At this time, the reliability module only interfaces with the powerflow module. Faults can currently only be induced on link objects within the powerflow module. Faults available are:
- SLG-A, SLG-B, SLG-C, SLG-X -> single-line-ground A, B, C, or random
- DLG-AB, DLG-BC, DLG-CA, DLG-X -> double-line-ground AB, BC, CA, or random
- LL-AB, LL-BC, LL-CA, LL-X -> line-line AB, BC, CA, or random
- TLG -> triple-line-ground - ABC
- OC-A, OC1-A, OC-B, OC1-B, OC-C, OC1-C, OC-X, OC1-X -> single open conductor A, A, B, B, C, C, random, or random (OC and OC1 are the same)
- OC2-AB, OC2-BC, OC2-CA, OC2-X -> double open conductor AB, BC, CA, or random
- OC3 -> triple open circuit - ABC
The following fault types are valid events in reliability calls, but should not be explicitly induced. These events are induced by switch or fuse objects when specific actions occur. They may show up in the output log of powerflow reliability calls, but should not be explicitly specified as a fault.
- SW-A, SW-B, SW-C -> open switch phase A, B, or C
- SW-AB, SW-BC, SW-CA -> open switch phases AB, BC, or CA
- SW-ABC -> open switch phases ABC
- FUS-A, FUS-B, FUS-C, FUS-X -> fuse tripping (forced) A, B, C, or random
- FUS-AB, FUS-BC, FUS-CA, FUS-X -> fuse tripping (forced) AB, BC, CA, or random
- FUS-ABC -> fuse tripping (forced) - ABC