Introduction
Power flow (or load flow) analysis is a fundamental element in electrical engineering, especially when it comes to grid-connected infrastructure projects. At Nettlefold Projects, our engineers frequently undertake power flow studies to support the safe, reliable, and efficient connection of new infrastructure, generators, and large industrial loads to the network.
This case study provides a real-world example of how power flow analysis plays a critical role in grid connection design and infrastructure upgrades. It also serves as a CPD learning resource for engineers seeking to expand their understanding of grid behavior under varying load and generation conditions.
Project Background: Grid Connection for Industrial Load Expansion
In 2024, Nettlefold Projects was engaged by a large steel manufacturing client in New South Wales to assess the feasibility of expanding their 11kV distribution network. The expansion involved connecting a new high-demand production line to the existing network, which already supplied several critical loads.
The key engineering challenge was to determine whether the existing network could accommodate the additional load without compromising voltage stability, thermal limits, or power quality.
Objectives of the Power Flow Study
The scope of the power flow analysis included:
- Evaluating steady-state voltage profiles across all feeders under different load scenarios.
- Assessing thermal loading on all upstream and downstream network components, including transformers, cables, and protection devices.
- Determining fault level impacts at key nodes within the system.
- Identifying reactive power requirements and opportunities for power factor correction.
- Recommending network reinforcement options, if required.
Methodology and Tools
Our engineers used industry-standard power system analysis software (such as ETAP and PowerFactory) to model the client’s existing network and simulate different operating conditions.
Key data inputs included:
- Existing single line diagrams
- Load profiles
- Transformer and cable ratings
- Utility supply constraints (based on Endeavour Energy’s network limits)
Analysis Scenarios Modeled:
- Peak production with all loads online
- Minimum load during off-peak production
- Worst-case voltage drop scenarios
- Fault and contingency scenarios (N-1 conditions)
Key Findings
- Voltage Drop: Without mitigation, the new load would cause voltage drops exceeding 6% at certain downstream nodes, breaching Australian Standard AS/NZS 61000.3.100 requirements for voltage quality.
- Thermal Limits: Two of the 11kV feeders were found to be operating close to thermal limits under peak conditions, indicating the need for load balancing or network reinforcement.
- Power Factor: The site’s aggregate power factor would fall below 0.9, increasing exposure to utility reactive power penalties.
Engineering Solutions Recommended
- Installation of a new 11kV feeder from the upstream substation to balance load distribution.
- Upgrade of selected transformer capacity to handle future demand growth.
- Implementation of a power factor correction system to maintain a site-wide PF above 0.95 lagging.
- Real-time power monitoring and control upgrades, enabling dynamic load management.
Outcome
Following Nettlefold Projects’ recommendations, the client implemented a staged upgrade of their internal network. This ensured compliance with grid connection standards, maintained power quality, and minimized operational risk during production ramp-up.
Our power flow study provided the technical assurance required by both the client and Endeavour Energy, enabling timely approval of the network connection application.
CPD Learning Points
For engineers undertaking similar grid-connected projects:
- Understand Load Diversity: Always consider varying operating conditions when modeling power flow.
- Factor in Power Quality Standards: Ensure compliance with AS/NZS voltage quality and harmonic distortion limits.
- Collaborate with Network Service Providers (NSPs): Early engagement with utilities like Endeavour Energy or Ausgrid is essential for grid connection approval.
- Plan for Future Expansion: Design solutions that allow for scalable growth, not just today’s load.
- Invest in Accurate Modelling: Reliable data and validated models underpin effective power system analysis.
Further Support
Nettlefold Projects offers specialist services in:
- Grid connection studies
- Power flow and load flow modelling
- Harmonic analysis
- Protection coordination
- Generator and industrial load connection
If you’d like to discuss your project or arrange a CPD training session for your team, Contact us here.
