A microgrid controller coordinates a particular combination of generation, storage, loads and other sources. Define the intended grid-connected or islanded modes and the objective of each. The presence of several technologies does not by itself establish a functioning microgrid.
Review transitions and source constraints
Each source has operating limits and interface requirements that affect coordination. Charging, reserve, load changes and transition behaviour need to be assessed using the actual equipment data. Uninterrupted transfer should not be promised without an applicable design and verification basis.
Possible responsibilities
- generator dispatch
- battery SOC management
- renewable curtailment
- load shedding
- grid import/export
- island transition
- resynchronisation
- reserve management
Grid-forming question
During island operation, some source must provide the electrical reference required by the island.
Safety > stability > resilience > economics
The control hierarchy should never sacrifice equipment or system safety for energy optimisation.
Define the control objective
A microgrid controller coordinates sources and demand according to the required operating strategy. Cost, reserve, renewable use and continuity can impose different priorities. Specify the intended modes and interfaces before choosing controller functions.
Treat performance claims as project-specific
Any proposed fuel, cost or continuity outcome depends on the load profile, equipment and control strategy. Record the assumptions and evidence required for validation. This page explains the planning questions; it does not establish current delivery capability or guarantee a particular project result.
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Review Technical Guidance • Request Engineering Review. Share the application, location and information available so the next discussion can address your actual requirement.
Related guidance
Engineering intent
Microgrid Controllers should be evaluated as part of the complete power system rather than as an isolated catalogue item. Operating duty, connected load, interfaces, protection, controls, installation conditions, testing requirements and lifecycle consequences determine whether the arrangement is appropriate.
Control-system requirement
The control architecture must connect sensing, source readiness, permissives, breaker or transfer commands, feedback, alarms, communications and fallback modes. An individual component test does not prove the complete operating sequence.
Engineering considerations
If the BESS interfaces through a transformer, its: UPS systems downstream of the island can continue protecting no-break loads. But they must accept the grid-forming BESS/DG bus as a valid input. UPS bypass architecture must also remain compatible with the island source. Do not assume bypass remains available under every island state. Traditional ATS logic can become more complex because: Source quality and transfer relationships must remain coordinated. A grid-forming hybrid system commonly requires coordinated control of: Microgrid Critical-Power Architecture remains the parent microgrid architecture page in the approved sequence. while a higher-level microgrid controller coordinates the system. Control hierarchy and tuning must be engineered as one system. The architecture should define what remains functional after communications loss.
Selection and design considerations
protection • inverter current control • governor control • AVR control The microgrid controller coordinates the system above them. Terminology varies by implementation, but the separation of timescales is valuable. DG governor/AVR and BESS PCS can respond on timescales much faster than ordinary supervisory optimisation. Do not route every dynamic action through SCADA. An appropriately engineered BESS PCS can potentially become the island’s grid-forming resource. But this capability must be verified for the actual PCS/control system. Synchronous generators can also establish island voltage/frequency. The microgrid controller must know which source/control architecture owns that role. can participate in grid-forming operation, their control relationship must be explicitly engineered.
Integration and protection considerations
Testing, commissioning and verification
When capacity returns, reconnect loads in a controlled sequence. Avoid simultaneous reconnection that creates a second overload event. Hybridisation can introduce additional states involving BESS and microgrid controllers. Determine whether the existing transfer equipment can be retained or needs modification/replacement. phase • frequency • voltage • breaker logic • kW/kVAr sharing. Where inverter sources join the architecture, define their control role separately. short-circuit levels • relay pickup • time grading • directional protection • islanding states. A protection study based solely on the old DG configuration may no longer be valid. The system may have different fault currents in: grid-connected • DG island • BESS island • DG+BESS island.
Operating and lifecycle considerations
then the PLC is a critical architectural dependency. For higher-consequence systems, redundant control architectures can improve availability where justified. Then I/O failure can defeat both control processors. A PMS coordinates electrical generation and load according to the plant architecture. They can integrate tightly but should not be treated as synonyms. EMS can coordinate energy resources such as BESS according to: with responsibilities potentially overlapping according to project architecture. A microgrid controller coordinates multiple distributed resources across: Microgrid Controller Architecture will deepen the control layer while Microgrid Critical-Power Architecture remains the resilience architecture layer. A multi-DG plant can require a master-level control system to determine: which DG starts • when another DG starts • which stops • reserve required • synchronising sequence.
Decision and application considerations
Reconnection after utility restoration depends on the approved interconnection arrangement, acceptable source conditions, synchronisation where required and the defined control sequence. Seamless transfer is not an inherent feature of every microgrid. Generation, storage, distribution, protection and controls must be engineered together for the required operating modes. Storage may support balancing, renewable integration, frequency control or backup where its power, energy and control capability are suitable. Confirm the actual system capability and operating permissions before relying on any particular transition.
Direct answer
A microgrid controller coordinates a particular combination of generation, storage, loads and other sources. Define the intended grid-connected or islanded modes and the objective of each.
The practical decision for Microgrid Controllers should be based on verified load, equipment, interface and site information. Where equipment-specific data, regulatory applicability or a project study is required, this guidance does not replace that verification.