The Canadian north is an expansive region with a low population density, which poses some unusual challenges to providing modern conveniences like on-demand electricity. The remoteness of many communities in the north makes it necessary to generate power locally. For most communities, this is accomplished with diesel generators. There are 55 diesel-powered communities among the three territories, with many more in the provinces. In an effort to reduce greenhouse gas emissions, many communities are looking to add renewable energy sources. However, this process is not as easy as plugging in some solar panels and turning off the diesel generators. This article will discuss the challenges of integrating renewable energy into remote communities.

Challenges of Microgrids

The small size of microgrids pose challenges to their stable operation that larger grids like the North American interconnected power grid do not need to consider. For example, in a large power grid with a load of 100 MW, using a 1.5 kW electric heater contributes 0.15% of the total load. However, the same heater used in a microgrid with a load of 100 kW would make up 1.5% of the load, a significantly larger difference.

Power producers must maintain a delicate balance where power generated equals power demanded, and this balance is even more important in remote communities. Due to the isolation of these communities, the minor inconvenience of a power outage can quickly turn into a serious situation. Additionally, the utilities may need to send personnel and equipment to resolve the issue, which can take significant time. This makes it critical that any changes to the system do not create reliability problems.

Renewable energy sources, like wind turbines and solar panels, must be carefully integrated into microgrids because of their intermittency, or in other words, their unpredictable power production. Unlike controllable diesel generators, intermittent renewable energy sources may produce electricity exceeding demand, fall short of meeting it, or, in the worst case, generate nothing at all, such as during periods of no wind or at night for photovoltaic systems.

Limitations of Diesel Generators

The properties of diesel generators are a significant consideration when determining the amount of intermittent renewable energy that can be integrated into a community. Efficiency and spinning reserve are the two main limiting properties.

Efficiency refers to the fact that diesel generators operate best between 50% and 90% of their rated capacity (maximum power output); however, operators typically restrict the operating range to between 50% and 80% for an added safety margin. Normally, the system controller needs to switch to a smaller diesel generator when the power demand on a generator drops below 50% in order to meet the decreased demand while maintaining optimal efficiency. The unpredictability of renewables can force diesel generators to operate below their optimal efficiency window, wasting fuel and reducing their lifetime.

Spinning reserve refers to the fact that generators must be able to meet an increase or decrease in demand within their operating range.

The operating generators must have the capacity to increase or decrease power output to adapt to changes in demand. If the generator runs out of reserve (room to increase or decrease power), the utility may need to add spinning reserve and share the load with a smaller or larger generator. This spinning reserve generator still consumes fuel and incurs wear and tear on the equipment, but doesn’t contribute to the power supply. If the renewable energy sources power production suddenly drops, the reduction in power could be enough to drop the diesel generators out of their efficiency window or require additional spinning reserve, thus increasing the total fuel consumption and operating costs. This is counterproductive to the overall goal of increasing energy reliability and decreasing emissions.

The solution to these problems is to limit the size of the renewable resource or to add an energy storage system to the project. The most common energy storage system is a battery energy storage system (BESS). BESSs are ideally suited for integration into renewable energy projects, as they can be utilized for both up and down reserve purposes by storing excess energy when renewable generation exceeds demand or supplying energy to mitigate spinning reserves. An appropriately sized BESS improves the usage of renewable energy and avoids the issues that intermittent resources like wind and solar can cause.

Project Success

An important part of a successful project is understanding what exactly success means. Every community has unique needs, so understanding how the project aligns with those needs helps tailor it effectively. Various aspects of the project can be changed to align with community goals, such as diesel plant relocation, diesel reduction, renewable energy sales, or turning the diesel generators off completely. Working to align the project with the community’s vision within the boundaries of the utility’s capability improves the chance of success.

Evaluation

To get a better idea of a project’s impact, a technical evaluation is required. This involves the making of a detailed computer model of the microgrid power system to run simulations that test the safety and performance of the grid with the renewable energy project integrated. Here at Northern Energy Innovation, we run four types of simulations, each of which assesses an aspect of the behaviour of the system. These simulations are comprised of Power Flow analysis, Time Series Power Flow analysis, Electro-magnetic Transients study, and Short Circuit analysis.

Power Flow: This simulation tests the extremes of normal operating conditions to ensure the infrastructure can handle all possible situations that could occur during regular operation. This shows us how adding a renewable energy source could impact voltages throughout the grid, which impacts households throughout the community.

Time Series Power Flow: This simulation runs a power flow simulation for each minute of a year. Unlike the previous simulation, this uses recorded real-world profiles for power demand, renewable generation, etc., and allows the general performance characteristics to be evaluated. These include metrics like diesel savings, renewable power generated, and the amount of time the diesel generator is turned off.

Electro-magnetic Transience: This simulation tests the effects of rapid electrical fluctuations from sudden events, like re-energizing the system or sudden faults. If these rapid electrical fluctuations are not managed, they can cause equipment damage or power outages.

Short Circuit: This simulation evaluates the system’s ability to isolate faults, such as branches falling on the lines or the lines hitting the ground, and prevent these faults from causing widespread damage or blackouts. This is very important for the utility since it tells them how to configure the fuses and reclosers in the system to avoid faults.

All these simulations are used in conjunction to meet the community’s project goals within the safety and regulatory boundaries placed on the utility.

Commissioning

The final step of integrating renewables is the commissioning process. After the construction has finished and the renewable is ready to be connected to the microgrid, the utilities will run a series of tests at limited power to evaluate the real-world performance and interaction with other systems. This is the opportunity to iron out problems with control logic, defective parts, or bad equipment interactions. Once the utility is happy with the performance, they will connect the renewable under continued observation until they are confident it will work and not jeopardize the system.

Integrating renewable energy into remote communities offers challenges and opportunities. Traditionally reliant on diesel generators, microgrids require a strategic approach to renewables. Overcoming diesel limitations is vital for reliable energy. Solutions like energy storage can help balance the variability of renewables with demand. Through careful planning, remote communities can achieve a sustainable, resilient energy future, cutting emissions and improving energy stability.

Author: MacKenzie Smith
Reviewed By: Trent Gardiner and Simon Geoffroy-Gagnon