System security and reliabilityProject Stability Enhancing Measures for Weak Grids Study
This first Performance Report presents findings related to weak grid classification and grid strengthening solutions. It focuses on the methodologies and data that will be employed in measuring a number of project outcomes.
Australia’s electricity network roadmap is to replace the critical role of synchronous generator-based plants such as coal-fired power plants with renewable, power-electronic-converter (PEC-)connected energy resources. The generation mix from PEC connected generators creates a power system with low levels of native inertia leading to a weak electricity network with low system strength. Additionally, with the majority of optimal sites for renewable energy generation (with access to high wind speed, high solar irradiance and high capacity transmission lines) already utilised, future developments need to focus on less favourable locations leading to the connection of newly developed solar/wind farms into weaker parts of the grid with lower system strength.
With an increasing number of PEC-connected generators, grid locations that are distant from the synchronous generators and close to PEC-connected ones experience low fault currents and low system strength. This results in a number of issues for wind/solar farms, including but not limited to post-fault instability, failure to feed in full power stably under steady-state conditions, startup and re-synchronisation issues, control interactions and instability, failure to ride-through disturbances, electromechanical oscillatory instability and islanding issues.