Technical education
Energy Transition and Power System Operation
The energy transition is changing how power systems are planned, operated and controlled. Traditional synchronous generation is being progressively complemented or displaced by renewable energy, inverter-based resources, battery storage, flexible demand and digital control systems. This creates new opportunities, but also new operational challenges for frequency regulation, voltage control, system strength and stability.
Core idea: The energy transition is not only a change in energy sources. It is also a change in the physical behaviour of the power system. As the share of inverter-based resources increases, the system becomes more dependent on fast controls, accurate forecasting, grid-forming capabilities, storage, flexible demand and advanced operational tools.
1. What is the energy transition?
The energy transition is the transformation of electricity systems from a generation mix dominated by conventional fossil-fuelled synchronous generators toward a mix with higher shares of renewable energy, distributed energy resources, storage, electrified demand and power-electronic interfaces.
In practical terms, the transition includes the integration of:
New energy sources
- • Utility-scale solar PV
- • Distributed rooftop solar PV
- • Wind farms
- • Battery energy storage systems
- • Hybrid renewable energy plants
New system capabilities
- • Fast inverter-based active power control
- • Advanced plant controllers
- • Demand response and flexible loads
- • Forecasting and digital operation tools
- • Grid-forming and system-supporting inverter functions
This transition reduces emissions and can lower energy costs, but it also changes how frequency, voltage and stability are maintained. Services that were historically provided naturally by synchronous machines must now be explicitly specified, measured, procured or enabled through controls and market mechanisms.
2. Characteristics of new generation technologies
Solar PV
- • Variable output depending on solar irradiance
- • Connected through power electronic inverters
- • Very fast active power control capability
- • Can reduce output during over-frequency events
- • Can increase output only if operating below available solar power
- • Does not provide natural mechanical inertia in standard operation
Wind generation
- • Variable output depending on wind resource
- • Modern wind farms are usually converter-interfaced
- • Can provide active power control through turbine and plant controls
- • Can support frequency if headroom or suitable control mode is available
- • Mechanical rotor energy is not naturally coupled to grid frequency in the same way as synchronous machines
Battery energy storage systems
- • Fast bidirectional active power response
- • Can inject power during under-frequency events
- • Can absorb power during over-frequency events
- • Useful for fast frequency response and regulation services
- • Limited by state of charge, converter rating and energy capacity
Distributed energy resources
- • Large number of small devices connected at distribution level
- • Includes rooftop PV, home batteries, EV chargers and controllable loads
- • Can create operational visibility and coordination challenges
- • Can become valuable flexibility resources if properly coordinated
3. New technologies and frequency regulation
Frequency regulation requires continuous balancing between active power generation and active power demand. New technologies can contribute to this balance, but they do so through different physical mechanisms compared with synchronous generation.
Synchronous generation
Mechanical response
Frequency support comes from rotating inertia, turbine governors and dispatchable fuel or water input.
Inverter-based resources
Control response
Frequency support comes from measuring frequency and changing active power through power electronics.
Flexible demand
Demand response
Frequency support can be provided by reducing or increasing controllable load.
For inverter-based resources, a simplified active power frequency response can be represented as:
Where P_cmd is the active power command, P₀ is the initial setpoint, K_f is the frequency response gain, f is the measured frequency, and f₀ is nominal frequency.
BESS is particularly valuable because it can respond in both directions: increasing injection when frequency is low, or absorbing power when frequency is high. Solar and wind can also provide frequency response, but upward response usually requires headroom, meaning the plant must be operating below available power.
4. Frequency regulation challenges during the energy transition
As synchronous generation is displaced by inverter-based resources, several frequency-related challenges become more important.
Reduced inertia
- • Frequency can change faster after a contingency
- • Rate of Change of Frequency can increase
- • Less time is available for primary frequency response
- • Fast frequency response becomes more important
Lower governor response online
- • Fewer synchronous units may be online to provide governor response
- • Frequency response must be provided by BESS, demand response and inverter controls
- • Operational tools must ensure sufficient response is available before a disturbance
Variability and uncertainty
- • Solar and wind output changes with weather conditions
- • Forecast error can increase balancing requirements
- • More flexible reserves and ramping capability are required
Distributed resource coordination
- • Large volumes of rooftop PV can reduce operational demand
- • Minimum demand periods can reduce synchronous generation online
- • Coordinated control of distributed resources becomes increasingly important
AEMO has highlighted that essential system services such as inertia, frequency control ancillary services, system strength, voltage control and operational flexibility can constrain renewable output when these services are required from other resources.
5. Angular stability and voltage stability challenges
Although this portal focuses on frequency, the energy transition also affects angular stability and voltage stability.
Angular stability
- • Traditionally linked to the synchronising torque between synchronous machines
- • Can be affected when fewer large synchronous machines are online
- • Power electronic controls change the dynamic behaviour of the system
- • Weak grids may require careful tuning of controls and protection systems
Voltage stability
- • Depends on reactive power support, voltage control and network strength
- • High inverter penetration can change fault current and voltage recovery characteristics
- • Weak areas may require system strength support, synchronous condensers, STATCOMs or grid-forming capabilities
- • Voltage control must be coordinated across transmission, distribution and plant controllers
6. Technologies and algorithms to address the challenges
Operating a future power system requires a combination of hardware, controls, markets, forecasting and digital tools.
Fast frequency response
- • Fast active power injection or absorption after a frequency event
- • Particularly suitable for BESS and fast inverter-based resources
- • Helps arrest frequency when inertia is lower
- • Implemented through technical requirements or ancillary service markets
Grid-forming inverter controls
- • Inverters that can establish voltage and frequency references
- • Can improve operation in low-inertia or weak-grid conditions
- • Relevant for BESS, hybrid plants and future renewable plants
- • Requires careful system-level integration and performance standards
Advanced plant controllers
- • Coordinate active and reactive power across many inverters
- • Implement frequency-watt and voltage control functions
- • Manage ramp rates and curtailment
- • Enable plant-level compliance with grid requirements
Energy storage optimisation
- • Maintains state of charge for frequency response availability
- • Coordinates energy arbitrage, reserve and network support
- • Optimises charging and discharging under operational constraints
- • Supports both normal operation and contingency response
Forecasting and probabilistic operation
- • Improves solar, wind and demand forecasts
- • Quantifies uncertainty and reserve needs
- • Supports unit commitment and dispatch decisions
- • Reduces risk from rapid renewable variability
Real-time monitoring and analytics
- • Uses high-resolution measurements to track system conditions
- • Detects frequency events, ramping events and abnormal behaviour
- • Supports post-event analysis and operational learning
- • Provides transparency for engineers, operators and stakeholders
Wide-area measurement systems
- • Use PMUs and high-speed measurements
- • Improve visibility of oscillations and dynamic behaviour
- • Support model validation and event analysis
- • Can help identify angular and voltage stability issues
AI and optimisation algorithms
- • Can support forecasting, anomaly detection and dispatch optimisation
- • Can help coordinate distributed energy resources
- • Must be validated carefully for safety-critical operation
- • Should complement, not replace, engineering judgement and power system studies
7. Conceptual operating model
8. Why this matters for Frequency Observatory
Frequency is one of the most visible indicators of the changing behaviour of the power system. As inverter-based resources increase, frequency behaviour becomes a valuable signal for understanding the interaction between demand, renewable generation, storage, reserves and control systems.
Frequency Observatory aims to make this behaviour visible through real measurements, technical education and accessible data. The objective is to support a constructive technical discussion about how modern electricity systems can remain secure, reliable and efficient during the energy transition.
References
- AEMO — Ancillary services and power system security services.
- AEMO — Renewable Integration Study, Stage 1.
- AEMO — Fast Frequency Response and very fast FCAS markets.
- NREL — Grid-Forming Inverters: Enabling the Next Generation Grid.
- NREL — High levels of inverter-based renewable generation and reliability considerations.
- NERC — Reliability guidance for frequency response, inverter integration and bulk power system operation.