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What is a power conversion system (PCS) and what does it do?

A bidirectional power electronics device that converts DC power from a battery into AC power for injection into the grid, and AC power from the grid into DC power for battery charging. In a utility-scale BESS, the PCS is the critical interface between the battery bank and the grid connection point. It controls charge and discharge rates, manages voltage and frequency response, and ensures grid code compliance.

What is the difference between PCS and PVI?

Both are built on Hitachi Energy’s common liquid-cooled platform but serve different plant configurations. PCS is for standalone BESS. PVI is a complete photovoltaic inverter station for standalone utility-scale solar PV. They can also be used for AC or DC-coupled hybrid solutions integrating both solar PV and battery storage into a single grid connection point. All controlled by the Power Plant Controller (PPC).

What is DC coupling in a solar-plus-storage plant and why does it matter?

In a DC-coupled plant, the solar panels and battery share a single DC bus and a single power conversion stage to the AC grid. This avoids the additional energy loss of an AC-DC-AC conversion step in AC-coupled designs.

What grid services can Hitachi Energy’s power conversion systems provide?

Primary and secondary frequency response, synthetic inertia, voltage regulation, reactive power support, ramp rate control and energy shifting.

What is the Power Plant Controller (PPC) and how does it integrate with a BESS?

PPC is Hitachi Energy’s supervisory control platform for renewable and storage power plants. It sits between the operator’s SCADA system and the power conversion devices, managing dispatch, grid code compliance, state-of-charge optimisation and fault management. PPC integrates directly with the battery management system (BMS) from leading battery manufacturers, reducing project complexity and commissioning time.