Evaluating the provision of regulatory aggregator services under irregularities after network disruptions or errors in forecast/measurement
ID | 18.02 |
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Reference to Test Case | TC18 Evaluation of various service definitions and activation patterns |
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Title of Test | Evaluating the provision of regulatory aggregator services under irregularities after network disruptions or errors in forecast/measurement |
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Test Rationale | This test investigates aggregator services that are involved in regulating the grid properties towards desired values in case of emerging deviations: - Coordinated voltage control
- Fast frequency response
- Virtual inertia provision
In the process, the individual activation patterns of the services undergo assessment. Simulation software provides the various auxiliary services required for their functionality: - Collection of updated capabilities from DERs
- Evaluation of automatic restoration reserve provision by DERs, storage units and controllable loads
- Computation of optimal and feasible P/Q set-point
- Verification of actual P/Q produced and possible recalculation
ICT-related effects are abstracted as activation delays, making this an “idealized” case. |
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Specific Test System | This Test Specification requires a simulator of a grid (MV/LV distribution network or single LV distribution feeder) with several connected DERs / storage units. |
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Target measures | - Safe and robust voltage for all nodes: Direct voltage operating regions not violated
- Frequency restoration time: <120sec
- Steady-state deviation: <0.1Hz
- Reserves availability (power/energy): >20%
- DERs curtailment: <30%
- Loads curtailment: <5%
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Input and output parameters | Uncontrollable input parameters: - Grid topology
- Generation and load profiles
- DER controllers parameters
- Tie-line exchange specifications
Controllable input parameters: - Voltage set-point
- Frequency set-point
- Load value
Output parameters: - Node voltages
- Power losses
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Test Design | The test considers several consecutive imbalances and voltage/frequency deviations in order to sufficiently evaluate the capability of the voltage/frequency control system to cope with such incidents. The following border cases are defined: - Maximally decrease input voltage/frequency, use constant voltage/frequency set-point
- Maximally increase input voltage/frequency, use constant voltage/frequency set-point
- Decrease voltage/frequency set-point from maximal to minimal value, do not artificially vary input voltage/frequency
- Increase voltage/frequency set-point from minimal to maximal value, do not artificially vary input voltage/frequency
- The operating set-points are determined.
- The output stabilizes.
- The input voltage/frequency and/or the set-points are varied according to the current border case.
- The test criteria are assessed.
- Steps 2-4 are repeated until the testing of each predefined border case was concluded.
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Initial system state | Initial power flow conditions: - The voltage/frequency value (output) matches the voltage/frequency set-point.
- The combination of the RES units should provide at least 20% of their nominal power.
- The consumption of the loads should be at least 20% of the maximum consumption.
- The imbalance should be under 5%.
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Evolution of system state and test signals | - At first, the system is sufficiently balanced with only a small amount of reserves (ideally zero) implemented and the voltage/frequency nominal.
- An imbalance emerges which leads to a significant voltage/frequency deviation and the consequent activation of a large part of reserves after a simulated communication delay.
- Consumption or production changes in order to reduce the variation.
- Subsequent disturbances emerge either before or after the restoration of voltage/frequency to its nominal value.
- Having started at Inp0, the voltage/frequency changes up to Val1, then down to Val2 etc. with varying step sizes (St1, St2, ...). For example, changes to the frequency could occur with a fixed ramp rate and amplitude.
- The test is successful if load voltage/frequency is always regulated within its operating interval [TOL-, TOL+].
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Other parameters | N/A |
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Temporal resolution | The simulation is continuous, with time step sizes depending on the software experiment: - Time constants inside SuT in-between 50 μs and 5 s
- Monitoring quantities with a maximum sampling time of 0.1 sec.
- Internal time resolution of communication simulation
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Source of uncertainty | - Grid parameters variability (i.e., resistance/inductance ratio)
- Timing deviations, communication delays
- Consumers’ demand
- Environmental conditions
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Suspension criteria / Stopping criteria | - Restoration and stabilization of regular network behavior and properties (according to power quality standard EN50160)
- Passage of predetermined critical amount of time
- Violation of quality attributes
- Deviation from initial conditions during start
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