What it is and when you need it
BESS (battery energy storage system) commissioning is the set of tests that proves the electrical side of the system is correctly built, correctly set and ready to connect to the grid. It covers everything from the power conversion system (PCS) outward: transformer, medium voltage switchgear, cables, interconnection protection, control and communications with the control center.
You need it for storage systems connected to a substation, for those installed next to a solar plant, and for those that industry uses for backup or to cut peak demand. The AC side is tested like any substation; the difference is that a BESS charges and discharges, so power changes direction several times a day and the protection and metering must be right in both directions.
What is included
Transformer and switchgear
- BESS transformer: ratio, vector group, winding resistance, insulation and short-circuit impedance.
- MV switchgear or ring main units (RMU): insulation, on-site dielectric test, contact resistance, timing and interlocks.
- MV cables and their terminations.
Protection
- Protection of the transformer, the switchgear and the point of interconnection, by secondary injection with the approved settings.
- Directionality and reverse power (32) in both directions of flow.
- Real trips of each circuit breaker, and transfer trip when the scheme uses it.
Batteries
- Battery tests: capacity or discharge, impedance or conductance, cell or monobloc voltage and inspection. The BMS itself is handled by the manufacturer.
PCS on the grid
- Verification of the PCS AC side: phase sequence, connection to the transformer, and trip and block signals between the PCS and the protection.
- Grid synchronization and response to active and reactive power setpoints, in coordination with the manufacturer.
Control and communications
- Consistency of measurements between BMS, PCS, relays and meters.
- Signals from the EMS and the plant controller to SCADA and the control center.
- Time synchronization of relays, recorders and gateway.
How we work
- Planning. We review the single-line diagram, protection study, settings, signal list and the manufacturer’s procedure. With you and the manufacturer we define which tests belong to each party and in what order.
- Safety first. Before the batteries are energized, the fire detection and suppression systems, ventilation and emergency stops must be tested. Those tests belong to the manufacturer and the contractor; we require them as a condition of the plan.
- De-energized tests. AC-side primary equipment and protection, with calibrated test equipment from recognized manufacturers (OMICRON, Doble, Baur, among others).
- Energization from the grid. First the busbar, then the transformer and switchgear, and finally the PCS, which synchronizes following the manufacturer’s procedure.
- Tests under power. Charge and discharge, power flow directions, protection directionality and response to setpoints, with the system exporting and importing.
- Interconnection tests. Those the grid operator requires for entry into operation, with their documentation.
Criteria and standards in BESS commissioning
The IEC 62933 series is the reference for electrical energy storage systems: IEC 62933-2-1 covers unit parameters and test methods, and IEC 62933-5-2 covers the safety of grid-integrated electrochemical storage systems. NFPA 855, the installation standard for stationary energy storage systems, often appears in project specifications. AC-side equipment is judged against its product standards and factory values, for example IEC 60076-1 for the transformer.
Interconnection protection, settings and tests are set by the project’s protection study and the grid operator, and monitoring by the system operator (SCADA and, where required, synchrophasor measurement) follows local code and utility requirements. The full path, with the stages and the risks specific to storage, is in the guide to BESS commissioning.
What you receive
- Test reports for the transformer, switchgear, cables and batteries.
- Reports for each relay and a backup of the loaded settings.
- Functional tests of the interconnection scheme, with trip times.
- Signal list verified with the control center.
- Energization report and report of the tests under power in both directions.
Why Tiza Group
- Substation judgment applied to the electrical side of the BESS, from the transformer to the control center.
- Experience in medium, high and extra-high voltage, in substations, industry and solar plants.
- Test equipment from recognized manufacturers (OMICRON, Doble, Baur, among others) for primary and secondary tests.
- One team for the solar plant and its storage, when they share the connection.
Field work is done in Colombia, or elsewhere on request. If the BESS sits next to a solar plant, see solar plant commissioning, or contact us to plan your project.