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What are Microgrids?

Microgrids are small-scale, low-voltage power systems that incorporate various distributed energy sources, storage devices, and controllable loads. They can operate while connected to the main power network or independently as an "islanded" system, all in a controlled and coordinated manner. Essentially, a microgrid is a self-sufficient energy system that serves a specific geographic area, such as a college campus, hospital complex, business centre, or neighbourhood.

 

Within a microgrid, you'll find one or more types of distributed energy sources, such as solar panels, wind turbines, combined heat and power systems, or generators, which produce the power needed. Additionally, many modern microgrids are equipped with energy storage capabilities, often in the form of batteries. Some microgrids also feature electric vehicle charging stations.

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It's important to note that a microgrid differs from a conventional minigrid commonly used for village electrification projects, as it allows for controlled management of energy sources and loads. It represents a comprehensive solution that combines both the generation and utilization of solar electricity.

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Microgrids consist of multiple energy resources, some independent and others controllable. These include solar and wind generators, which are mainly independent and intermittent, as well as fossil fuel generators (such as diesel or gas), battery storage, thermal storage, hydrogen generators, controllable loads (both short-term and long-term), and other miscellaneous loads.

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In the case of a rural microgrid, the following loads can be combined:

  • Mini cold storage

  • Ice plants

  • Milk chillers

  • Water purifiers

  • Water pumping for small-scale irrigation

  • Battery charging for electric farm machinery and transportation

  • Communication systems

Most of these loads are flexible and can be controlled as needed.

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When connected to the main grid or embedded within it, a microgrid appears as a single, steady load or source to the overall network. Any fluctuations or disturbances that occur are typically contained within the microgrid itself. In the event of a disruption in the main grid, a microgrid has the ability to isolate and operate autonomously. Microgrid designs generally prioritize the maximization of local generation from renewable sources.

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In summary, microgrids are sophisticated energy systems that provide localized power and enhance resilience by utilizing distributed energy sources, storage, and controllable loads. They can operate connected to the main grid or independently, ensuring reliable and sustainable energy supply for specific areas or communities.

For more information about Microgrids please refer to this article: What is a Microgrid?

Oztron Energy offers specialized services for Microgrids. These include:

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  • Feasibility

  • System Design, Detailed Design and Optimization

  • Steady-state and Dynamic modelling

  • Control System Design

  • Approvals and certifications

  • Supply of critical components like battery storage, controllers, electrical switchgear, communication systems

  • Construction, as required

  • Commissioning

  • On-going Maintenance and Management

Case Study 1

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100kW Microgrid in a Waste Processing plant

 

This Microgrid powers the workshop in a waste processing plant near Perth. There is a provision to connect nearby building to this existing network. It is about 1.5km away from the nearest grid connection and it is unviable to extend the grid to cover this load. Earlier the site was entirely powered by a 100kVA diesel generator operating during the working hours and would be shut down for the night.

 

Loads

  • Workshop lighting, air-conditioning, tools, computers etc.

  • Compressor, intermittent use.

  • Hoist, electric welding – as required

 

Continuous load is around 10kW but occasionally it would go up, with a large surge when the hoist or welding are operated. The generator was rated to handle the surge loads. But most times it would operate at 8% to 10% capacity. This is inefficient and increases the maintenance requirements.

 

Present Configuration

  • 100kWp roof-top PV

  • 100kW Hybrid Inverter, with MPPT

  • 22 nos Lithium Ferrous Phosphate batteries, total 125kWh, 422V

  • Oztron EMS and PV Distribution Board

  • 100kW diesel generator, existing

 

The Oztron EMS monitors and controls the Inverter, Batteries, PV and the generator so all the resources are coordinated and managed efficiently from remote. If any component is not performing properly, it can be isolated and the site can keep operating. Detailed logs are maintained which can be utilized for warranty purposes. Any deviation from normal operating conditions, like high internal temperature, is notified remotely for manual intervention, if required. The EMS manages the diesel generator to operate if the battery level falls low and the solar is not sufficient to charge. The generator would then operate at its optimum load of about 80% and supply the load and charge the battery.

 

Current Operations

  • The inverter has sufficient capacity to operate the high surge loads

  • At present load the generator does not need to come on at all, even during the winter months

  • The EMS forces the generator ON for about 15 minutes every day to ensure that it is kept in running order

  • The generator is never operated in an underloaded condition. This, together with the reduced operational hours, has reduced the maintenance requirements greatly

  • Security lighting and other essential loads can operate through the night

  • Some more load from a nearby shed is proposed to be connected, but the total will still stay below the capacity of the microgrid generating system.

 

Project Scope of Work

Perdaman Advanced Energy: 

  • Project management, execution 

  • Installation

Oztron Energy: 

  • Concept and detailed design

  • Supply of batteries, inverters and switchboards

  • Design, supply and commissioning of the control systems

  • Ongoing monitoring and remote management

Case Study 2

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100kW Irrigation Microgrid

 

This microgrid provides electricity to an off-grid rural property about 2 hours from Perth. Normally the site is unattended.

 

Loads

 

Four Irrigation Pumps 5kW, 2 x 30kW and 75kW. The 75kW pump is currently not in operation. In season time the pumps are operated continuously, night and day. Provision to connect the workshop and the Manager’s accommodation.

 

Present Configuration

  • 100kWp ground mounted solar array

  • 100kW PV Inverter

  • 100kW Hybrid Inverter

  • 230kWh Lithium Ferrous Phosphate batteries, Inverter and battery in a single cabinet

  • Oztron EMS and PV Distribution Board

  • 270kW diesel generator, existing

 

EMS & Monitoring

  • The Oztron EMS monitors and controls the Inverter, Batteries, Solar and the generator

  • Full remote monitoring, operation and troubleshooting

  • Any defective component can be isolated, while the site keeps operating.

  • Detailed logs are maintained

  • Alarms and abnormal conditions are notified remotely

  • Full remote visibility of the entire microgrid

  • Multiple redundant power supply for continuous operation even with prolonged power outage

 

Operation with EMS

  • Generator comes ON if the battery level falls low and the solar is not sufficient.

  • The generator operates at its optimum load of about 60%, supplies the load and charge the battery.

  • Meets generator minimum loading requirement.

  • The pumps are controlled remotely via EMS.

 

Current Status

  • The Microgrid is in continuous operation.

  • The pumps are operated as required.

  • The owner is considering increasing the capacity to accommodate the larger (75kW) pump.

 

Project Scope of Work

Owner:

  • Installation

  • Execution

 

Oztron Energy:

  • Concept and detailed design

  • Supply of batteries, inverters and switchboards

  • Design, supply and commissioning of the control systems

  • Ongoing monitoring and remote management

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