Global Electricity Grids are Changing
The Duck Curve
As renewable energy generation increases grid loading becomes much less predictable. High penetration of solar energy results in a"duck curve" where loading on the energy grid varies dramatically through the day and have rapid load changes. This can result in dangerous grid instability and potential blackouts.
Inverter Dominated
Renewable Energy Generation is dominated by inverter sources (where AC power is generated from DC wind and solar by inverters) as opposed to spinning generators. This makes the grid more vulnerable to load swings as there is no large spinning inertial mass to smooth out load change. Inverter technology and energy storage will need to advance to ensure a stable grid.
Distributed Energy Generation
With rooftop solar, local batteries, and wind farms generation is far more distributed among different, smaller generator rather than single large generators. The grid was not designed with this architecture in mind and can bottleneck different energy distribution interconnects.
Energy Storage Is Required
Without proper energy storage these changes make the grid far less stable, reliable and robust.
Grid scale (MW) batteries will be required to properly operate a clean energy grid and ensure energy security.
Virtual Power Plants (VPP)
Supplying the Grid with Energy when it Needs it Most
As the gird changes monolithic, centralized generation is being replaced by decentralized distributed generation. These many distributed sources are often networked together to operate as a single Virtual Power Plant (VPP).
Many smaller solar and battery energy storage systems are often networked together to behave as a competitive VPP which can actively participate in the energy wholesale market and provide power when the grid needs it most and prices are highest.
Frequency Stability and Ancillary Markets
Frequency Control Ancillary Services (FCAS)
In an electrical grid the Generated Power and the Load Power must always be equal. As you switch on a light bulb the grid has to respond in real-time. This is primarily controlled by the grid frequency. When loading increases the frequency of the grid slightly droops and when loads are turned off the frequency slightly rises.
Grid operators are constantly adjusting generator power output to control this frequency. In an inverter based renewable energy grid this becomes challenging.
To help stabilize frequency energy market operators pay market participants to provide Frequency Control support by rapidly increasing power availability in the grid or rapidly increasing load to help control frequency and hence grid reliability. This service is known as FCAS.