About the project
MetaPV is a major industrial-scale demonstrator project showcasing how photovoltaics can provide active grid support in historically grown distribution networks . It shows that intelligent control of photovoltaic inverters can increase the capacity of a network for hosting distributed generation by 50%. This is possible at less than 10% of the costs of classical grid reinforcement. The report provides caveats, guidelines and recommendations on how this can be done in practice. See www.metapv.eu for more information.
- Integration of a 60 kWh LiOn battery into the grid for buffering PV fluctuations and cost-of-energy optimization
- Three-phase active grid frontend that can be reconfigured as a 270 kW 3-wire system or a 180 kW 4-wire system
- Implementation of ancillary services including power factor correction, power balancing and harmonic filtering
The figure below outlines the MetaPV test setup which is installed at a warehouse in Sint-Truiden, Belgium. The setup connects a 60 kWh LiOn battery to the main grid thereby buffering the fluctuations from a PV installation. At the heart of the setup is a Triphase PM90 multi-converter system. It consists of three 90 kW sections that can be configured both as a 270 kW 3-phase, 3-wire grid frontend or as a 180 kW, 3-phase, 4-wire frontend. The PM90 sections facilitate a bidirectional exchange of energy between the battery and the grid.
This flexible and reconfigurable grid interface enables researchers to explore strategies for short-term buffering of fluctuations due to PV installations as well as cost-of-energy optimizations. As such, they want to identify viable business cases. Moreover, researchers can program the installation to provide ancillary services including power factor correction, power balancing and harmonic filtering. Acillary services like this help to reduce the burden on the distribution grid thereby optimizing grid usage.
The setup also allows researchers to compare different storage technologies and their fitness for these kind of grid-tie applications. This includes the evaluation of battery life time as a function of power profiles. This kind of research facilitates cost-effective battery technology selection.
The setup consists of:
- A 180 kW active front-end with active controlled neutral wire
- A PV array on the roof, connected to the main grid through commercial PV inverters
- A 750V, 60 kWh kWh battery pack, connected to the Triphase Power Module's DC bus
- Several balanced and unbalanced loads connected to the main grid
- A voltage and current measurement device installed at the main grid connection
Scope of delivery and customer developments
- CAN Interface with BMS
- SOC-dependent power setpoint limiting
- Power flow management: Managing the power flows between grid, PV array and battery
- Energy buffering: Strategies to decide when to store PV energy into the battery and when to release energy to the grid. This includes grid-capacity and cost-of-energy optimizations.
- Grid support: The active power is controlled as to assist the grid in maintain a stable voltage frequency and amplitude.
- Power factor correction: The power factor a the main grid interface is controlled at 1 by using the converter system to inject reactive power.
- Grid phase-balancing: At the main grid interface, the power distribution is balanced over the three phases by using the converter system for power transfers in between phases.