Cambodia Battery Completes Black-Start Test Across 240 Km Network
Cambodia's 108.4 MW / 215.6 MWh Kandal Stueng battery has completed acceptance testing that Sungrow says included black start, islanded operation and restoration of a 240 km transmission network.
Published · 4 min read
Sungrow says a 108.4 MW / 215.6 MWh Cambodia grid-forming battery has completed grid connection and full acceptance testing at the EDC Kandal Stueng station in Kandal Province, including a black-start demonstration that energized transmission infrastructure and helped restart conventional generation. The company announced the milestone on September 29.
The project is significant because the tests went beyond ordinary battery charging and discharging. According to Sungrow, 516 grid-forming power-conversion units established voltage and frequency from a de-energized condition, supported restoration of roughly 240 kilometers of transmission lines and five substations, and operated the restored network with hydropower, thermal generation, storage and loads.
Cambodia grid-forming battery completes acceptance testing
Sungrow’s September 29 project announcement identifies the facility as the Cambodia EDC Kandal Stueng station, or GS79, in Takmao. The company reports a rated capacity of 108.4 MW / 215.6 MWh, equivalent to roughly two hours of storage at maximum rated output.
Sungrow says the plant completed full acceptance testing after grid connection. The company has not published the complete independent test report or identified a third-party verification body in the announcement, so detailed performance figures should remain attributed to Sungrow.
The underlying grid location is credible in broader system records: Kandal Steung appears as a major high-voltage substation in Cambodia’s transmission network. The new disclosure adds a large storage resource and grid-forming controls at that part of the system.
The black-start test rebuilt voltage from zero
The most technically important claim is the black-start sequence. Sungrow says 516 grid-forming PCS units energized the plant from zero voltage, establishing the voltage and frequency reference required to begin restoring the surrounding electrical system.
That is different from a conventional grid-following battery. Grid-following inverters normally synchronize to an existing electrical reference, while grid-forming controls can establish or regulate that reference when the system is weak or de-energized.
Microgrid Media’s evergreen guide to microgrid black start explains the same restoration principle: a suitable resource must first establish an energized electrical reference before additional generation and loads can be brought back in a controlled sequence.
The test included transmission lines, substations and generation
Sungrow reports that the restored system included approximately 240 kilometers of transmission lines and five substations. During the sequence, the battery supported startup and synchronization of the 60 MW Kamchay Hydropower Plant before the islanded network was operated with the 135 MW CIIDG coal-fired plant, energy storage and loads.
The company also says the system remained stable through five transformer-energization events, including a transformer rated up to 100 MVA. Transformer energization can create substantial inrush currents, making it a meaningful stress test for a newly established electrical island.
Sungrow further reports 3.5 hours of independent islanded operation and three transitions between grid-connected and islanded modes. During grid separation, the company says voltage deviation remained below 2% and transient frequency fluctuation remained within 0.15 Hz.
Those are unusually specific test results, but they remain vendor-reported until supported by an independently available acceptance report or system-operator document.
Grid-forming storage is moving from feature lists into system tests
Battery suppliers increasingly market grid-forming capability, but the distinction between having a capable inverter and demonstrating system-level restoration matters. A black-start sequence requires controls, protection, auxiliary power, switching and adequate stored energy to work together, not simply a software setting on individual power-conversion units.
Microgrid Media has examined the same engineering distinction in its coverage of Queensland’s Supernode Stage 3 project, where grid-forming technology is part of a much larger battery expansion designed to support the transmission system.
The project also illustrates why commissioning is central to storage reliability. Microgrid Media’s guide to microgrid design and black-start planning notes that restoration capability depends on sequencing, protection, control logic and testing under realistic operating conditions.
The next step is independent operating evidence
Sungrow says the Kandal Stueng project completed a compressed commissioning and test program, including three rounds of performance testing. The company also says the plant’s grid-forming controls are intended to support voltage and frequency stability at a key point in Cambodia’s central grid.
What is not yet publicly available is equally important: the complete acceptance criteria, state of charge during each restoration test, third-party validation, long-term availability data and details of how the battery will be dispatched under normal grid conditions.
The Cambodia grid-forming battery therefore clears a meaningful technical milestone without proving every broader performance claim. If the reported black-start and islanding results are confirmed through continued operation, the project would provide a useful real-world case of a utility-scale battery acting not only as an energy-shifting resource but as an active grid-restoration asset.
