Test Specification 16.01

16.01

TC16

Black Start algorithm verification

This test verifies the ability of the centralized BS controller to disconnect/reconnect parts of the grid and resources in the right order and at the right timing. The order of actions is fixed and predefined through the programming parameters of the control system, whereas the reconnection timing should happen automatically at times when voltage and frequency are within specific boundaries.

The test setup depicted above comprises one BS controller (as part of the DMS), three loads with controllable switches, three transducers for the voltage measurement at each load (on the breaker’s side), one transducer for the measurement of frequency and one controllable source which provides the voltage/frequency controllability required for validating the controller behavior.

• Power outage time
• Reconnection times
• Voltage/frequency values

Input parameters

• Frequency
• Voltage

Output parameters

• Breaker state
• Load voltage
• Controllable source activation

The specific test makes use of the controllable MV source to emulate the blackout condition as well as the BS generation provider. Therefore, the source’s output can be deactivated manually and reactivated through a communication signal from the BS controller. In the real system, the specific signal is the start-up command from the BS controller to the BS generator. The voltages at each load should be monitored on either end of the breaker in order to verify:

• Disconnection/reconnection time
• If the voltage conditions for reconnection are suitable

Moreover, by monitoring the frequency at the source’s output it is possible to:

• Verify that the controller reconnects the loads within the proper frequency conditions and in the right order
• Verify that the start-up command to the BS generator is communicated correctly and in the right order

Even though some voltage/frequency stability is presumed for the test, the limits for these values, especially frequency should be not considered as tight as in normal operation. Therefore, the frequency limits for this test are considered from 47.5 to 52 Hz with a ROCOF <2 Hz/s. The corresponding voltage limits are considered as +5% and -5% of the nominal voltage.

• The controllable source supplies the system with constant voltage at frequency at nominal values (fsource=50 Hz, Vsource=1 p.u.)
• The three breakers are closed, and the loads are supplied
• The BS controller is reset to its initial state (normal operation)
• The BS controller continuously monitors frequency and voltages in order to detect a possible blackout

• At a predetermined moment, the source’s output is deactivated and the voltage and frequency become zero emulating the blackout conditions
• This time is recorded as reference for calculating the response times of the various components
• The BS controller detects the loss of voltage and initiates the BS procedure
• Initially, the BS controller disconnects all three loads from the grid
• After a specific interval (<1 min), the BS controller dispatches the start-up signal to the controllable source
• The output of the source is monitored in order to calculate the time required for this step until re-energization is restored
• The BS controller continuously monitors the voltages and frequency in order to detect when the conditions are proper for reconnecting the loads
• The load voltages are recorded to measure the reconnection order as well as the proper voltage/frequency conditions during reconnection

N/A

A sampling time of <1 s is enough for this test to provide the necessary information since the responses of the controller signals range in the order of several seconds to minutes.

Uncertainties that may appear in this test are due to the precision of the various instruments used to measure the voltage/frequency responses. Additional uncertainties may be introduced by the communication channel delays between the BS controller and the various controllable components.

The test should be suspended and restarted if one of the quality attributes described in the TC is not met or if the algorithmic procedure of the BS controller does not perform as should be expected.