Test Case TC16

Version management

Author

Evangelos Rikos, Julia Merino, Andres Cortes

Version

1.0

Project

ERIGrid 2.0-NA4

Date

22/02/2021

Narrative

The focus of this TC is on MV distribution grid where one central controller can perform the following actions: isolate/disconnect/ reconnect lines and/or resources and initiate grid-forming DGs. The DGs that provide the BS service should have resilience in significant frequency/voltage variations to cope with large imbalances during re-energization and for a typical duration of at least 1 hour. The scope of the TC is to verify the system’s ability to achieve a smooth re-energization within the prescribed duration.

Function(s) under Investigation (FuI)

• Black-start control
• Primary voltage control
• Primary frequency control
• Secondary frequency control
• Secondary voltage control

Object under Investigation (OuI)

• Distribution Management System (as the provider of the BS and secondary control functionalities)
• Inverter-based DGs (as providers of the power/energy needed for system re-energization and as primary control resources)

Domain under Investigation (DuI)

• Electrical Power
• ICT (time-delays)
• Electrochemical
• Environmental

Purpose of Investigation (PoI)

• Validation of Black-Start capability

System under Test (SuT)

The main components and subsystems that are of interest for this TC are depicted in the above diagram and summarized below:

• Distribution Management System (DMS)
• Circuit breakers
• Battery energy storage system (BESS)
• Distribution Grid

Functions under Test (FuT)

• Battery Management System
• MPPT
• Load control
• SCADA
• Energy Management System

Test criteria (TCR)

• Frequency response
• Voltage response
• Battery capacity

Target Metrics (TM)

• Maximum Voltage deviations (±5%)
• Maximum frequency deviations (47.5 Hz–52 Hz)
• Maximum ROCOF
• Response/stabilization time
• Maximum Energy Availability
• Number of sequential start-ups (at least three)

Variability Attributes (VA)

Fully Controllable attributes:

• Circuit breakers’ state
• Primary and secondary control parameters
• Inverter control functionalities

Partly Controllable attributes:

• Loads’ active/reactive power
• Generators’ active/reactive power

Uncontrollable attributes:

• Solar irradiation
• Wind speed
• Ambient temperature
• ICT and control delays

Quality Attributes (QA)

• Sampling time of signals (frequency, voltages, Power/energy flows): <1sec
• Resolution:
  • frequency 0.05 Hz,
  • voltage 0.005 pu
  • Power 0.01pu
• Points of measurement:
  • Frequency: at least 1
  • Voltage: 1 point for each resource connected at their electrical output
  • Battery power/energy flow: 1 point at the output of the BESS

Qualification Strategy

In order to meet the specific PoI, which is the evaluation of the distribution system’s Black Start capability, three separate test specifications are required: -One test is related to the partitioning of the system. That is how the centralized BS controller manages to disconnect and reconnect components of the grid, either resources (loads, generators) or lines. The test validates the correctness of the disconnection order of components, as well as the ability of the controller to reconnect them at times when voltage and frequency are well within specific boundaries and more or less stable. -The second test verifies the ability of the system to maintain voltage and frequency within specific boundaries after the BS generator is started up by the BS central controller. The specific operating limits for this test are more relaxed as opposed to the ones that apply in normal operation. -The third test is a sort of endurance test which validates the BS generator’s ability to provide the service for a minimum time duration (e.g., 1 hour). In other words, this test comes down to verifying the energy reserve of the BS generator.