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Power Systems AnalysisCompleted Technical Study

Ofosu Islanded Solar Mini-Grid - ETAP Power-System & Protection Study

Independent ETAP reconstruction and technical assessment of the Ofosu standalone mini-grid, covering 24-hour PV-BESS operation, islanded short-circuit behaviour, generator and inverter-based fault contribution, device-duty screening, and representative feeder protection coordination.

Ofosu Islanded Solar Mini-Grid - ETAP Power-System & Protection Study project visual

Project Visual

Location

Ofosu, Nigeria

Period

2026

01 / Engineering Scope

Technical work and responsibilities.

  1. 01

    Develop and review the Ofosu standalone mini-grid model in ETAP with PV generation, BESS/PCS, diesel generation, transformers and the 11 kV distribution feeder.

  2. 02

    Assess 24-hour islanded PV-BESS power sharing and network voltage performance.

  3. 03

    Evaluate generator-only islanded short-circuit performance.

  4. 04

    Screen protective-device duty under the generator-only fault condition.

  5. 05

    Assess islanded PV-BESS short-circuit behaviour and device duty.

  6. 06

    Evaluate representative downstream feeder selectivity using an LV breaker and upstream 11 kV overcurrent protection.

02 / Delivery Outcomes

Measured project results.

  1. 01

    Completed a 24-hour islanded operating assessment showing daytime PV support, surplus-energy absorption by the DC/BESS side and overnight BESS supply.

  2. 02

    Observed solar generation reaching approximately 400 kW in the modelled daily profile while supplying the community load and network losses.

  3. 03

    Evaluated generator-only short-circuit behaviour using the modelled 0.556 MVA diesel generator.

  4. 04

    Identified materially lower islanded fault levels on the 11 kV feeder than on the LV buses, highlighting the importance of protection sensitivity in islanded operation.

  5. 05

    Completed PV-BESS islanded short-circuit and device-duty assessment using the configured ETAP inverter-based resource models.

  6. 06

    Demonstrated selective operation for a representative three-phase fault at the Load 1 bus: downstream CB12 cleared at 60 ms, Relay1 operated at 298 ms, and upstream CB11 opened at 358 ms.

Technical Areas

Methods, tools and disciplines.

01

ETAP 24

02

Time-Domain Load Flow

03

Islanded Operation Assessment

04

PV-BESS Power Flow Analysis

05

IEC 60909 Short-Circuit Analysis

06

Device Duty Screening

07

Protection Coordination

08

ETAP Star / TCC

09

Sequence of Operation

Related Disciplines

Mini-GridETAPSolar PVBESSDiesel GenerationIslanded OperationTime-Domain Load FlowShort CircuitIEC 60909Device DutyProtection CoordinationSelective Coordination

Project Evidence

Selected engineering evidence.

Field photographs, drawings, GIS outputs, commissioning records and technical reports approved for public portfolio use.

01

Engineering Drawings

1 item

02

Reports / PDFs

6 items

PDF

Reports / PDFs

ETAP Single-Line Diagram - Full Resolution

Full-resolution PDF export of the ETAP single-line model used for the Ofosu mini-grid assessment.

Sep 2026

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PDF

Reports / PDFs

Case 1 - 24-Hour Islanded PV-BESS Operational Assessment

Time-domain assessment of 24-hour PV-BESS power sharing, network voltage performance, equipment loading and system losses under standalone operation.

Sep 2026

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PDF

Reports / PDFs

Case 2A - Generator-Only Islanded Short-Circuit Assessment

IEC short-circuit assessment of the islanded network with the modelled diesel generator acting as the principal rotating fault-current source.

Jul 2026

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PDF

Reports / PDFs

Case 2B - Generator-Only Device-Duty Assessment

Protective-device duty screening under the generator-only islanded short-circuit condition.

Jul 2026

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PDF

Reports / PDFs

Case 3 - Islanded PV-BESS Short-Circuit & Device-Duty Assessment

Islanded short-circuit and device-duty assessment evaluating the configured PV and BESS inverter-based fault-current contributions.

Jul 2026

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PDF

Reports / PDFs

Case 4 - Islanded Hybrid Feeder Protection Coordination

Representative feeder protection study demonstrating selective operation between downstream CB12 and the upstream Relay1/CB11 protection combination for a three-phase fault at the Load 1 bus.

Sep 2026

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