What Frequency Ride-Through Is
Frequency ride-through is the ability of electrical equipment (especially inverter-based devices like PV inverters, battery inverters, and sometimes EV charging systems) to remain connected and operate safely during short-term grid frequency deviations outside the nominal value (50 Hz or 60 Hz), within defined limits.
Instead of disconnecting immediately when frequency shifts, the device “rides through” the event to support grid stability and avoid unnecessary outages.
Why Frequency Ride-Through Matters
If many devices disconnect at once during a frequency disturbance, it can make the disturbance worse. Ride-through requirements help:
– Prevent cascading disconnections that destabilize the grid
– Maintain service continuity for critical loads and infrastructure
– Improve resilience in weak or stressed networks
– Meet grid-code requirements for distributed energy resources
– Avoid nuisance shutdowns during temporary frequency events
Where Frequency Ride-Through Is Used
Frequency ride-through is most commonly specified for:
– DER inverters (PV, BESS, wind)
– Microgrids and grid-forming/grid-following inverter systems
– Industrial sites with sensitive power electronics
– In some cases, EV charging infrastructure as part of broader site power quality requirements
How It Works
A device monitors grid frequency and follows programmed rules:
– If frequency deviates but remains within a defined ride-through window, the device stays connected
– If frequency exceeds the permitted range for too long, it disconnects for safety
– Some devices reduce or adjust output (or charging power) as frequency moves, depending on control settings and grid code
Ride-Through vs Trip Settings
– Trip settings: thresholds where the device disconnects
– Ride-through settings: allowed frequency deviation range and duration before disconnection
Ride-through is designed to avoid “hair-trigger” trips while still protecting equipment and people.
Relevance to EV Charging
EV chargers are primarily loads, but ride-through considerations can still matter:
– Depots and hubs benefit from chargers not dropping out during minor grid events
– Sites with DER and an EMS may coordinate behavior during frequency events
– Some markets may require specific ride-through behavior for connected power electronics, depending on how chargers are classified locally
Key Design Considerations
– Local grid codes and DNO/DSO requirements (frequency limits and time curves)
– Interaction with voltage ride-through and protection devices
– Safe fallback behavior after ride-through (restart logic, ramp limits)
– Logging of events for diagnostics and compliance evidence
– Coordination with site EMS controls (avoid oscillations or conflicting responses)
Common Pitfalls
– Overly sensitive frequency thresholds causing nuisance trips
– Ride-through settings that conflict with safety protection design
– No controlled restart/ramp after an event → inrush peaks or instability
– Not documenting settings → hard to prove compliance during audits
Related Terms for Internal Linking
– Voltage ride-through
– Power quality
– Frequency response
– Grid congestion management
– Energy management system (EMS)
– Distributed energy resources (DER)