Solarna Systems Demo Pack 02

Demo Pack 02

Hybrid mini-grid controls

An illustrative controls concept for a PV, battery, generator, and load mini-grid. It demonstrates operating states, permissives, interlocks, fail-safe responses, alarm logic, HMI structure, and test planning.

Representative controls example - not a completed installation. Topology, thresholds, interfaces, and protections require project and OEM validation.

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Operating states

Define system behaviour before writing control logic.

Mini-grid controls fail when the operating philosophy is vague. This state model gives the site team a shared view of normal operation, generator support, battery protection, and fault handling.

Standby PV priority Battery support Generator-supported Fault lockout

State conditions

StateEntryExit
PV priorityPV available and SOC healthyPV low or SOC limit reached
Battery supportLoad exceeds PV while SOC and PCS limits permit dischargePV recovers, discharge floor is reached, or generator support begins
Generator-supportedValidated low SOC, load support request, or scheduled exerciseStop criteria met after minimum run; unload and cool down before stop
Fault lockoutProtection trip or unsafe telemetryManual reset after investigation

Control philosophy

  • Prioritize available PV while bus conditions, equipment limits, and battery constraints remain healthy.
  • Request generator start only from validated SOC, power, schedule, or fault criteria with hysteresis.
  • Prevent unsynchronized closure, unintended backfeed, and generator/BESS paralleling unless the approved design permits it.
  • Log every automatic state change for commissioning review.

Automation logic

Interlocks, alarms, and I/O mapping in a reviewable format.

Interlock

Generator start permissive

  1. 01Validated SOC below the start threshold for 180 seconds
  2. 02No active emergency stop or protection trip
  3. 03Generator available, in remote mode, and breaker proven open before crank
  4. 04Speed, voltage, and frequency valid; warm-up complete before the approved transfer sequence
Inputs

I/O map snapshot

TagTypeUse
BAT_SOCAnalogGenerator start/stop logic
GEN_READYDigitalStart permissive
INV_FAULTDigitalFault lockout
LOAD_KWAnalogPeak load support
Alarms

Alarm matrix

AlarmSeverityAction
Low SOCHighStart generator sequence
Communications lossHighInhibit affected transitions and enter the defined fail-safe response
Breaker mismatchHighBlock transfer
OverloadCriticalLoad shed request

Operator screens

HMI structure built for fast troubleshooting.

A clean HMI helps the operator understand which source is serving the load, why a transition happened, and what needs attention before reset.

Mini-grid dashboard concept

82 kWSite load
67%Battery SOC
PV priorityActive state
0Critical alarms

Conceptual AC-coupled topology only. The grid-forming source, neutral and earthing arrangement, breaker logic, and permitted paralleling mode must be defined for the project.

Screen list

  • Overview screen with source status, load, SOC, generator state, and alarms.
  • Energy screen with PV, battery, generator, load, and daily totals.
  • Alarm screen with severity, timestamp, acknowledgement, and operator note.
  • Settings screen with protected thresholds and commissioning records.

Commissioning handover

Make controls testable before the site goes live.

Factory test plan

Simulate SOC, PV availability, breaker status, generator readiness, and communication loss.

Site acceptance test

Verify state transitions, interlocks, alarms, HMI values, manual reset, and event logging.

Operator handover

Provide alarm response notes, reset rules, operating limits, and support escalation path.

Next step

Discuss a comparable controls scope.

A project controls package is developed from the approved operating philosophy, equipment interfaces, protection scheme, and test plan.

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