By Daniel Watson, Automation Solutions Innovator, Yokogawa
Distributed energy resources such as solar and wind are pivotal for reaching net zero energy goals, however, the intermittent nature of these renewables can cause an influx of many un-coordinated distributed energy resources that can threaten the reliability of a power grid. However, the solution lies in intelligent and advanced control platforms that take a renewable-first approach.
Arguably the largest issue currently garnering attention in the utility and process control space is that of energy. Oil shortages, fuel and electricity price spikes and the unprecedented halt of the electricity trading market on the east coast of Australia last year have jolted us from our COVID-19 haze drawing focus once again to the topic of renewables and what role they can play. For so long just seen as an environmental saviour, now there is wider appeal in lowering the cost of energy, improving the quality of power and meeting carbon neutrality.
The latest Integrated System Plan (ISP) from AEMO highlights looming step changes, the most promising of which is the forecast of total renewables generation at 83 per cent by 2030. However, to achieve this some major investment in the grid is required. Investment that needs to be focused on latest technology use for more intelligent control.
There are three key areas that need to be addressed as part of the energy transition: management and increased penetration of distributed energy resources (DERs); increasing independence from the grid; and reliable dispatchable power. The Yokogawa PXiSE controller is designed to solve all these challenges in a logical and renewable first manner. Other controllers are often aimed at making renewables fit into the existing grid, whereas the PXiSE vision is focused on 100 per cent renewables, 100 per cent of the time, taking a more advanced controls approach.
Distributed energy resources
Part of the AEMO plan is to address increased penetration of DERs. Projects like Edge and Symphony help to give a commercial mechanism for leveraging household resources, but we also need platforms to maximise their potential and control their impact on the grid, for many this is a utility problem, and utilities are looking for DER Management Systems (DERMS), like PXiSE, to solve this challenge.
DERs are at the stage where they are creating issues during peak periods by supplying more power than the grid requires, potentially more than the power network can handle, and causing stability issues where the voltage is pushed high, even leading to restricting the amount of rooftop solar. The concept of Dynamic Operating Envelopes (DoEs) through DERMS was introduced to give a safe maximum operating window to individual resources.
Taking a renewable first approach will aim to focus on maximising the power supplied by these DERs, in the case of Horizon Power the household DERs can supply 100 per cent of the renewable energy on the grid. This control is possible by integrating the grid generation/despatch controls with the DERMS controls, and by ingesting weather forecasts it is possible to shut down all hydrocarbon generators and leverage only the DERs with a battery for stability – no need for load banks or synchronous condensers.
Grid independence
To help the energy transition one key step that can be taken is to cut the level of dependency on the grid and traditional generation. This is particularly important for commercial and industrial facilities, remote towns and communities, however, is equally applicable to residential use.
The Victorian Government has already announced the development of islanding remote community microgrids to combat the impact of natural disasters. Independence relates to the amount of power demanded from the grid and the level of reliance on it, especially during peak periods.
With the increased DER penetration, the daytime energy supply is high, thus being a consumer during this period can be advantageous, and being a supplier during the evening demand peaks can be financially beneficial. It is possible to actively control the power at your point of grid connection so that users can decrease demand without physically needing to cut the cord.
For example, at Santa Rosa Junior College in California the PXiSE Microgrid controller is designed to maximise the potential of behind the meter renewable generation and storage as well as control HVAC to manage the power across the point of interconnection netting them $330,000USD in annual energy savings and $170,000USD in demand charges.
There are additional positives to increasing independence, in the case of the Santa Rosa college they are now able to island the site from the grid, meaning the college can continue to function in the event of a power outage as the campus is supplied completely by renewables.
Combining DER control gives the ability to perform demand response and load enabling to ensure that operations can continue for days while disconnected.
Reliable dispatchable power
The grid runs on a fine balance of supply and demand. This balance has been achieved through a network of power generation assets that have a continual fuel source, such as coal or gas. When looking to run a renewable-first grid this level of dispatch needs to be achieved through storage such as a battery and pumped hydro.
Wind and solar have a capacity factor of approximately 30 per cent meaning that a significant oversupply of these resources is needed to meet the average demand. The storage is used to compensate when there is a drop in the renewable output, and smart deployment of storage can be used to pick up the intermittency, and act as long duration supply either overnight or during longer periods of cloud cover.
In the case of a microgrid, or a facility looking to have grid independence, the variability in the renewable resources can result in ten to 15 per cent more fuel usage if no storage is used and this can also cause greater power instability. In some of the Pacific Island projects PXiSE found it was normal to have frequency fluctuations of +/-1Hz, mostly due to renewable variability and diesel not being able to ramp quickly enough.
The solution to this is a co-located battery with very high speed, and forward planning controls. The battery can be used as a shock absorber for the system as well as a safety net. High speed controls of an appropriate battery can keep frequency variations to less than +/-0.01Hz and with automated planning and forecasting the battery state of charge can be optimised and maximised to ensure that the most renewable energy is used before we fall back to hydrocarbon-based resources.
The Australian energy transition has been spurred on by a few drivers, with frequent bushfires and floods highlighting a need for change, as is rising energy costs and aging infrastructure. The cost of doing nothing is now outweighing the cost of the change.
Anyone exposed to the spot price market during 2022 would be very aware of the volatility in the market currently, and in many cases the cost of renewables would have been offset by the power prices. Through a few simple planned steps and approaches to redesigning the grid, a renewable-first grid can be setup, hopefully halting the rising electricity prices.
This sponsored editorial is brought to you by Yokogawa. For more information, please visit www.yokogawa.com/au.
