PV Curves Setup: Injection Group Ramping Options

 

These options are found at the top of Setup tab found on the PV Curves dialog and the Injection Group Ramping Options tab of the same dialog. The remainder of the setup options are found on sub-tabs for Common Options and Advanced Options.

 

 

The Setup tab contains the options for defining the source and sink for the PV study transfer. The PV tool expects the source and the sink to be injection groups defined by the user.

Source

Use this drop-down box to identify the source injection group. To model an increase in transfer, generator points in the source injection group will increase their output, and load points will decrease their magnitude in amounts proportional to their participation factors.

If the injection group to use for the source has not already been created, click the View/Define Groups button in order to create it. After the injection group has been created, it will show up in this drop-down box and can then be selected.

Sink

Use this drop-down box to identify the sink injection group. To model an increase in transfer, generator points in the sink injection group will decrease their output, and load points will increase their magnitude in amounts proportional to their participation factors.

If the injection group to use for the sink has not already been created, click the View/Define Groups button in order to create it. After the injection group has been created, it will show up in this drop-down box and can then be selected.

View/Define Groups

If injection groups have not been previously defined in the current case, they can be created by clicking on this button. To create a new injection group, right-click on the resulting injection group case information display and choose Insert from the popup menu.

Alternatively, if a list of injection groups has been previously saved in an auxiliary file, they can be loaded into the current case by right-clicking on the resulting injection group case information display and choosing Load > Auxiliary File from the popup menu.

 

Island-Based AGC Tolerance

When implementing the transfer, island-based AGC is used. Injection changes for the transfer are first made to the source injection group, and when the power flow is solved, the sink injection group is adjusted for any injection changes due to the source injection group changes and any changes in losses due to the transfer. Because the process to determine required injection changes during the power flow solution MW control loop is an iterative process, a tolerance value must be specified to determine when the changes to the sink injection group are acceptable. This tolerance is NOT the same value that is set with the power flow solution options for specifying island-based AGC.

As a general rule of thumb, the Minimum Step Size should be at least 2 times larger than this tolerance. If not, all changes due to an incremental transfer that is smaller than this tolerance will actually occur between the source and the system slack instead of the source and the sink.

See the Tolerances in PV Tool topic for more information about how the AGC tolerance interacts with the Minimum Step Size and power flow MVA Convergence Tolerance.

Allow only AGC units to vary

Individual generating units are distinguished according to whether they do or do not participate in the automatic generation control (AGC) effort. Each generator has a field that determines whether or not that particular generator is AGC-able. By checking this option, only those generators whose AGC field is set to YES will contribute to the power transfer being studied. Otherwise, all units in the injection groups will be allowed to participate regardless of their AGC status.

Enforce unit MW limits

If this option is checked, the output of any participating generating unit will be kept within its designed operating range of MinMW < Output < MaxMW. When a unit is pegged at one of its limits, participation factors of the other points in the limited generator's injection group will be adjusted to pick up the difference.

If this option is checked and during the ramping all units in either the source or sink hit their limits, the scenario for which the ramping is being done will be considered critical. The Critical Reason for the scenario will reflect whether the source or sink ran out of resources.

Do not allow negative loads

This is the analog of the previous option for loads. If a load is used as a source point (or sink point when choosing to apply the reverse transfer), it will be decreased to make power available for the transfer. Checking this option will instruct the PV process to keep loads from falling below 0 MW. If a particular load is capped at 0 MW, participation factors for the remaining points in its injection group will be recalculated to make up the difference. If there are not enough resources in the injection group to continue with the transfer, the scenario for which the ramping is being done will be considered critical. The Critical Reason for the scenario will reflect whether the source or sink ran out of resources.

Ramping Method Modified in version 19, build on Aug. 4, 2016

Several different injection group ramping methods are available. These can be selected separately for either the Source or Sink.

Proportional

The MW output for generators and loads in the injection group will be adjusted in proportion to their specified participation factors. These factors will be normalized for all generators and loads participating in the dispatch. Mvar load will be adjusted according to the options found on the Advanced Options tab.

Merit Order

Injection group generators and loads will be dispatched by moving individual generators and loads to their maximum/minimum MW limits as appropriate in succession based on their relative participation factors ordered from highest to lowest. Generator MW limits will be enforced for those units participating in the merit order dispatch regardless of how the Enforce unit MW limits option is set. Loads that have both their minimum and maximum MW limits set to zero will not be allowed to increase. They can only decrease to 0 MW. Mvar load will be adjusted by keeping a constant power factor.

Economic Merit Order

This method involves dispatching generators so that they are dispatched within an economic range. Details about how economic merit order dispatch is performed can be found under the Generator Economic Merit Order Dispatch topic.

If using this option and an injection group contains ONLY loads, the loads will be adjusted in proportion to their participation factors and economic merit order dispatch will not be used.

Merit Order Close Added in version 19, build on Aug. 4, 2016

This method will dispatch generators in a merit order determined by their specified participation factors. Economic generator limits will be enforced during this process regardless of how the Enforce unit MW limits option is set. Details about this method can be found under the Generator Merit Order Close Dispatch topic.

If using this option and an injection group contains ONLY loads, the loads will be adjusted in proportion to their participation factors and merit order close dispatch will not be used.

 

Injection groups have their own set of options that can override the options on this dialog if they are in use. See the Injection Group Specific Scaling Options topic for more information.