An alternative approach to Grid Impact Assessment

Victoria's grid regulator VicGrid is settling on a new assessment method to approve renewable energy projects outside designated Renewable Energy Zones. The approach uses PSS/E power flow modelling across representative scenarios (high wind, high demand) to test whether new projects cause excessive network curtailment of existing REZ generators. This replaces an earlier two-test framework and aims to give applicants a clearer pathway to demonstrate their projects will not harm REZ buildout. The methodology remains incomplete: the article notes an unresolved question about what happens when a test shows additional congestion under certain operating conditions.

Where this fits

This is a reliability and cost story. Grid Impact Assessment rules are a workaround for a structural problem: the grid now has so much weather-dependent generation that congestion management has become the planning bottleneck. VicGrid is trying to route more renewables into designated zones where transmission is pre-built, but this creates a two-class system and leaves the real problem unaddressed: a grid firmed by gas dispatch burns more fuel under high-wind/high-solar conditions because inverter output and storage ramp rates cannot substitute for dispatchable power. The effort to assess "no harm" projects is an attempt to manage congestion without building the firm capacity or transmission spine that would eliminate it.

What it means

Victoria is optimising the renewable build-out process, not the grid's ability to deliver firm power reliably and cheaply. Clearer GIA rules do not resolve the underlying mismatch: weather-dependent capacity cannot be firmed at cost-effective scale by batteries alone, and transmission overbuild is the alternative. Australia's energy security depends on grid resilience. A system constrained by renewable curtailment and dependent on gas dispatch under peak-wind conditions is less resilient and more exposed to fuel-price volatility than a grid anchored in firm, low-material generation.