Template: AEMO Dynamic Model Acceptance tests (DMAT)

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Last updated: 2 Oct 2024

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PSS®E

PSCAD™

Source: AEMO | Dynamic Model Acceptance Test Guideline | Version 3 | 3 June 2024

Background

The number and complexity of user models have increased during the energy transition. In an effort to ensure models are "usable..., numerically robust, and represents the installed plant...", AEMO requires proponents to meet a collection of requirements and complete a series of Dynamic Model Acceptance Tests - collectively referred to as "DMAT".

Importantly, DMAT does "...not assess compliance of any given plant with performance or access standards at its connection point". Although DMAT can often reveal potential plant performance issues, it is not an assessment of those performance issues. Instead, it is an assessment of the models themselves.

"Table 22 DMAT" refers to a subset of DMAT and represents a "list of minimum mandatory tests". "Full DMAT" refers to completing all of DMAT. The gridmo template can be configured to run either "Table 22 DMAT" or "Full DMAT" by enabling/disabling loops - noting that the loop variable l_is_full_or_t22 has been created to distinguish Table 22 (T22) tests easily.

Configuration

To use this template:

Configure your Global Variables and Scenario Variables using gridmo's Model setup template.
Add this template into your project in the web app.
The template is configured to run "Table 22 DMAT" by default. To quickly enable all tests to run "Full DMAT", complete the following:
- Right click on any Loop Start Node in the flow, click on Select all Loop Start Nodes, then right click again on the same Loop Start Node and click Enable all loops.
- Enable the following Nodes:
  - Start Node 1501 - Table 3 (Tests 1 - 36): Balanced faults
  - Loop Start Node 1513 - Table 12B (Test 192): 2 deg phase oscil
By default, the template assumes "lowest SCR value of 3. If the SCR values are expected to be lower than 3 at the generating system’s or integrated resource system’s connection point, then the expected SCR values for system normal and the most severe credible contingency should be used". Therefore, choose the correct SCR and X/R values for your project, namely:
- [Default] If your project's minimum SCR ≥ 3, then you may use the default SCR and X/R ratio values provided (i.e. SCR_min=3, X/R_min=3, SCR_max=10, X/R_max=14).
- If your project's minimum SCR < 3, then you should replace the SCR and X/R operations conditions with your project specific min and max values.
Follow the below setup steps.

Source energy helper

Some tests in this template require the generator under test's source energy to be varied (where source energy is solar irradiance, wind speed etc.) Specifically, this template requires the source energy to be varied such that available active power can be limited to values such as 100%, 80%, 70%, 60%, 50%, 40%, 30% and 5%. The relationship between source energy and terminal active power [MW] of a generating unit is typically non-linear and may be specific to particular OEM models, especially for PSCAD™ wind turbine models (i.e. wind speed v.s. active power).

Helper 1: Source energy (Node 1175) has been provided in the template to help you understand the relationship between source energy and terminal active power [MW] of a generating unit. We recommend running the source energy helper Run, which loops over different source energy values using the loop variable l_se_step. You need to update the values of l_se_step depending on the PSCAD™ model source energy requirements and units. Some common options may be:

l_se_step [p.u.] (Default in template): Source energy is expressed in per unit on machine base. Loop over values from 0 to 1.
l_se_step [W/m²]: Source energy is irradiance and expressed in W/m². Loop over values from 0 to 1000.
l_se_step [m/s]: Source energy is wind speed and expressed in m/s. Loop over values from 0 to 40.

The output of the source energy helper Run is a scatter plot and spreadsheet which provides the relationship between terminal active power [MW] of the generating unit and source energy. Once you understand the relationship between source energy and terminal active power [MW], update the relevant Loop Variables in the following Loop: Start Nodes:

Loop: Start Node 1387
Loop: Start Node 1392
Loop: Start Node 1450

Table 2 (Tests 0.1 - 0.3): Flat run, snapshot and initialisation

The purpose of Table 2 is to demonstrate your model's ability to run a long flat run in a robust manner, initialize in < 3 seconds accommodate the snapshot functionality.

note

Tests 0.4 and 0.5 (snapshot and initialisation tests) have not been included in our template as providing a plot as evidence of a successful snapshot is likely insufficient.
We recommend running a broader range of operating conditions to confirm initialization in < 3 seconds (e.g. P_min/P_max, Q_min/Q₀/Q_max, SCR_min/SCR_max+X/R_min/X/R_max). For such tests, see our Model setup template.
The default simulation time for the PSCAD™ Nodes has been reduced to 30 seconds to reduce initial run time. Prior to completing and submitting this DMAT as part of a package, you need to increase the simulation time for all PSCAD™ Nodes connected to Start Node 1291 from 30 seconds to 300.

Table 3 (Tests 1 - 36): Balanced faults

The purpose of Table 3 is to demonstrate your model's robustness across a range of operating conditions and balanced faults.

Table 4 (Tests 37 - 120): Unbalanced faults

The purpose of Table 4 is to demonstrate your model's robustness across a range of operating conditions and unbalanced faults.

Table 5 (Tests 121 - 125): Unbalanced MFRT

The purpose of Table 5 is to demonstrate your model's robustness across different balanced and unbalanced MFRT sequences.

note

Sequence S1 is fixed. In accordance with the AEMO requirements, we generated sequences S2 to S5. These sequences are deterministic and are detailed in the MULTIFAULT Command.

Table 6 (Tests 126 - 130): Balanced MFRT

The purpose of Table 6 is to demonstrate your model's robustness across different balanced MFRT sequences. As the faults are balanced, the plots are benchmarked with PSS®E and PSCAD™ by default.

note

In accordance with the AEMO requirements, we generated sequences P1 to P5. These sequences are deterministic and are detailed in the MULTIFAULT Command.
3.2.8: If protection tripping is not captured by the MFRT sequences and explicit confirmation of protection is required, use the part of S5.2.5.4 of the AEMO Generator Performance Standards (GPS) template which causes UV and OV trips.

Table 7 (Tests 131 - 148): TOV

The purpose of Table 7 is to demonstrate your model's robustness across different temporary over voltage (TOV) tests.

Step 1 - Choose TOV methodology

Some engineers prefer to use a voltage source playback model rather than a capacitor switch-in for TOV tests. Both options have been provided in the template and you can choose which methodology to use.

Table 8 (Tests 149 - 166): Vref, Vgrid, Qref and PFref steps

The purpose of Table 8 is to demonstrate your model's ability to operate in different reactive power control modes.

note

Figure 3 is assumed to refer to Thévenin equivalent voltage source steps (i.e. Vgrid).
Figure 4 y-axis, "Reactive Power Reference [pu]" is assumed to have a base unit of the generating system rated active power [MW].
Tests 161 - 166 are conducted for both fixed reactive power control mode and power factor control mode.
Tests 155 - 166: We assume that the initial connection point voltage is 1.0 p.u. rather than default connection point voltage. The note, "Voltage Reference is applied as a relative change (whereas the figure indicates an absolute change from 1.0 pu) from the starting voltage reference of the plant or production unit controller, taking into account system strength, reactive power flow and the droop functionality" is ambiguous since it only refers to the Vref test and not the Vgrid/Qref/PFref tests.

Table 9 (Tests 167 - 169): Pref steps

The purpose of Table 9 is to demonstrate your model's ability to operate in active power control mode.

Step 1 - Choose time between Pref steps

Choose the time between Pref steps such that "the timing is expected to be of sufficient duration to allow reduction to occur". This simulation time will depend on your active power control mode gains as well as your ramp up and ramp down control limits (e.g. expressed in MW/sec). If required, edit the simulation time of the relevant PSS®E Dynamic, PSCAD™ and Plot Nodes.

Table 10 (Tests 170 - 177): Frequency ramps

The purpose of Table 10 is to demonstrate your model's ability to operate in frequency control mode.

note

Tests 170 - 173: Figure 7 contains 4 grid frequency ramp profiles which are designated with the following test number suffixes:
- A: 4 Hz/s ramp to 52Hz.
- B: 4 Hz/s ramp to 51.75Hz.
- C: 4 Hz/s ramp to 51.5Hz.
- R: 2/3 Hz/s ramp to 52Hz (i.e. "...frequency reaching 52 Hz over 3 seconds").
We assume that tests A and R are required as part of Table 22.
Tests 174 - 177: Figure 8 contains 2 grid frequency ramp profiles which are designated with the following test number suffixes:
- A: 4 Hz/s ramp to 47Hz.
- R: 1 Hz/s ramp to 47Hz (i.e. "...frequency change of 1 Hz/second over 3 seconds").
We assume that tests A and R are required as part of Table 22.

Table 11 (Tests 178 - 179): Grid voltage changes

The purpose of Table 11 is to demonstrate your model's ability to respond to grid voltage changes.

note

Figure 10: The figure shows three different test methodologies and we have included each methodology (e.g. Test 186A-10 is Test 186 with the first X/R configuration and 10% extended dip grid voltage recovery).
Tests 186 - 189: The extended dip grid voltage recovery is created through a combination of two events. This methodology helps to avoid using a Thévenin equivalent voltage source playback for very low voltage dips (e.g. 10%) which has been known to cause unrealistic and undesirable generating systems responses. The two events are:
- A fault impedance applied at 5 seconds for a duration of 500ms.
- A Thévenin equivalent voltage source playback ramp at 5.5 seconds for a duration of 1 second.

Table 12 (Tests 190 - 192): Grid oscillation rejection

The purpose of Table 12 is to demonstrate your model's ability to reject grid voltage amplitude and phase oscillations.

note

Test 192: Note 26 outlines that "The upper frequency at which tests would be conducted will depend on the control system bandwidth and may need to cover up to and including nominal frequency. At least tests up to 20Hz shall be performed as a minimum in all circumstances". The minimum requirement of tests up to 20Hz has been selected by default.

Table 13 (Tests 193 - 198): Grid voltage angle changes

The purpose of Table 13 is to demonstrate your model's ability to respond to grid voltage angle changes.

note

In accordance with Note 29, we have split each test event "Grid voltage angle change equal to ±40° and ±60°" into four different dynamic simulations, rather than having a single dynamic simulation with multiple subsequent angle changes (i.e. the tests are "treated as standalone steps"). This helps users isolate and resolve issues as well as decrease simulation time due to better simulation parallelization capability. The four tests are designated by the following:
- P40: Positive 40 degrees (+40°)
- P60: Positive 60 degrees (+60°)
- N40: Negative 40 degrees (-40°)
- N60: Negative 60 degrees (-60°)
For SMIB studies, we set the Thevenin equivalent voltage source angle as the 0° reference. Therefore, the initial angle at the POC will not be 0° for initial conditions where there is significant active and reactive power flow across the Thevenin equivalent impedance (e.g. Ppoc = 1 pu).

Table 14 (Test 199): Pref steps - SCR=1

The purpose of Table 14 is to demonstrate your model's ability to output active power under very low grid SCR conditions. For many generating system technologies "it is expected that the plant is unable to maintain stable operation at 100% output level". Table 14 investigates at which point this instability may occur.

Step 1 - Choose time between Pref steps

Choose the time between Pref steps such that the timing is expected to be of sufficient duration to allow reduction to occur. This simulation time will depend on your active power control mode gains as well as your ramp up and ramp down control limits (e.g. expressed in MW/sec). If required, edit the simulation time of the relevant PSS®E Dynamic, PSCAD™ and Plot Nodes.

note

DMAT outlines the requirement to overlay the simulation results for both PSS®E and PSCAD™ overlay, however PSS®E may not converge at such low system strengths. In the template, PSS®E is disabled by default, but can be enabled if desired.

Table 15 (Tests 200 - 205): Balanced faults - SCR=1

The purpose of Table 15 is to demonstrate your model's fault ride through capability under very low grid SCR conditions. For many generating system technologies "It is expected that the plant/model performance would not be able to sustain operation at SCR = 1".

note

The requirement methodology is unclear. The test description requires "pre-disturbance SCR conditions are lowered to SCR=1" but the contents of Table 15 outlines pre-fault and post-fault SCR, implying post-disturbance SCR conditions are lowered to SCR=1. We have assumed the latter.
DMAT outlines the requirement to overlay the simulation results for both PSS®E and PSCAD™ overlay, however PSS®E may not converge at such low system strengths. In the template, PSS®E is disabled by default, but can be enabled if desired.

Table 16 (Tests 206 - 225): Balanced faults

The purpose of Table 16 is to demonstrate your model's robustness across a range of operating conditions and balanced faults.

note

We assumed that Q = 0 MVAr operating condition tests are required for Table 22 DMAT and Qmax/Qmin operating condition tests are only required for Full DMAT. Additionally, we have assumed Q = ±0.3 MVAr for Qmax/Qmin in accordance with the comment, "In absence of specific levels, +0.3pu and -0.3pu could be used".

Table 17 (Tests 226 - 229): Source energy changes

The purpose of Table 17 is to demonstrate your model's ability to consider source energy changes.

Step 1 - Choose source energy change methodology

Choose a source energy change test methodology.

The requirement methodology is unclear for Tests 228 and 229 where the description requires a change in source energy "from reduced output levels". Two common methodologies have been provided below. Update Loop: Start Node 1450 in accordance with the desired methodology. Methodology 2 is simpler and may be required for some OEM PSS®E models which are not capable of initializing at a source energy which is different from the associated Pref value.

Methodology 1 [Default]
Methodology 2

Test 228: The initial source energy chosen to represent "from reduced output levels" is 40% with a +20% step to 60%. This methodology tests both that Ppoc is initially being limited to ≈0.4 p.u. even though Pref is 0.5 p.u. and that the Ppoc only rises to 0.5 p.u. even though the source energy available rises above the Pref value.

Test 229: The initial source energy chosen to represent "from reduced output levels" is 60% with a -20% step to 40%. This methodology tests both that Ppoc is only 0.5 p.u. despite source energy available beyond the Pref value of 0.5 p.u. and that Ppoc is being limited to ≈0.4 p.u. even though Pref is 0.5 p.u.

Section 3.3: IBR - LVRT/HVRT studies

Vgrid steps showing LVRT/HVRT transition bands isn't currently in this template. If required, use the S5.2.5.5 LVRT/HVRT transition band tests from the NER Chapter 5 Typical Generator Performance Standards (GPS) template.

Section 3.4: IBR - Grid voltage changes at reduced source energy

Figure 3 (Vgrid steps) at reduced source energy isn't currently in this template. If required, duplicate 'Table 8 (Tests 155 - 160): Vgrid steps' in this template and modify the Loop Variables as required.

Section 3.5: IBR - Minimum SCR verification

Verification of minimum declared SCR isn't in this template. We have assumed this has been superseded by SSIAG requirements. See the System Strength Impact Assessment Guidelines (SSIAG) template.

Section 3.6: Synchronous machines

The purpose of Section 3.6 is to demonstrate your model's excitation limiters. In the absence of explicit test numbers for this section, we have created the following test numbers:

Step 1 - Choose initial Qpoc values for Case study 1 and Case study 2

Choose initial Qpoc values for Case study 1 which correspond to the following operating conditions:

Qpoc "starting from within the generator’s capability curve...[where] the final settling value [from a -5% Vref step] should be just within the UEL and should not enter into any limiter, including the UEL". The default value is -0.05 [p.u.].
Qpoc "starting from within the generator’s capability curve...[where] the final settling value [from a +5% Vref step] should be just within the OEL and should not enter into any limiter, including the OEL". The default value is +0.05 [p.u.].

The values should be chosen based on the generating system capability curve and excitation limiter configuration. These values should be inserted into column l_qcmd in Loop: Start Node 1792.

Choose initial Qpoc values for Case study 2 which correspond to the following operating conditions:

Qpoc starting from within the UEL where a -/+5% Vref step "engages and disengages the limiter action". The default value is -0.2 [p.u.].
Qpoc starting from within the OEL where a +/-5% Vref step "engages and disengages the limiter action". The default value is +0.2 [p.u.].

The values should be chosen based on the generating system capability curve and excitation limiter configuration. These values should be inserted into column l_qcmd in Loop: Start Node 1781.

Step 2 - Choose Pmin values for Case study 1 and Case study 2

Choose Pmin values corresponding to the generating system minimum operating limit. These values should be inserted into column l_pcmd in Loop: Start Node 1792 and Loop: Start Node 1781. The default value is 0.05 [p.u.] to be consistent with the remainder of the template even though this is most likely incorrect for synchronous machines.

note

Case study 1: By assuming that the Qpoc values for "5% step in Vref starting from within the Under-excitation limiter (UEL)" and "The final settling value should be just within the UEL and should not enter into any limiter" are the same, we can complete a ±5% Vref step in a single dynamic simulation and reduce the Loop: Start Node configuration requirements. This methodology choice also maintains consistency with the methodology in Case study 2.