Here, Philippe Aretz, Channel Sales Director from Ovarro, looks at how RTUs overcome the challenge of collecting field data from a more diversified power generation sector.
Diversification of the energy sector creates both opportunities and challenges. It helps prevent disruption of supply and maintains security, giving the network additional resilience as well as creating new investment platforms, particularly smaller renewable projects.
The challenges are centred around additional generation sources requiring more management input, which places increased demand on the grid’s operational systems.
One way of maintaining efficiency in these situations is to deploy Remote Telemetry Units, which collect, analyse and interpret data from a vast array of assets.
Wind, solar, hydro, biomass and wave solutions have all grown in prominence in recent years to such an extent that in most developed countries around the world they now produce a growing proportion of the total energy output. This recently exceeding 20% for the first time in the UK.
Crucially, the power industry has always used RTUs to manage the power grid, however, these are designed to suit large interconnection points. An example would be a 1-Gigawatt(1GW) power station and here the RTU used to monitor and control these full-scale power distribution assets is very different to that required for a renewable source.
Compared to large coal, gas and nuclear plants where a single point of entry to the system carries the bulk of supply, operators in the ‘new’ sectors need to manage a much wider portfolio of assets with much smaller demands at each location.
Smaller, smarter RTU’s are needed
Solar, biomass and wind suppliers measure their supply in Kilowatts, rather than Gigawatts. At these relatively smaller sized power connections to the network, the asset monitoring and control RTUs used for a full-scale power distribution from a 1GW or greater station would be overkill.
As a result, there has been growing demand for smaller, smarter RTUs which can be cost effectively deployed on a wider range of assets, but still provide operators with the data they need to manage their networks.
For instance, the TBox RTU has been used for decades to monitor power consumption at critical assets. One of the earliest examples of its use was to monitor power consumption and battery backup at telecommunications towers.
In the event of a grid failure, the RTU would allow operators to continue monitoring their assets to help them decide what actions needed to be taken to ensure continued operations of the network.
These kinds of RTUs, even with a small footprint, have enough capacity to manage the limited number of I/O points that are required at each power generation tower.
Demand for RTU’s in the power sector continues to grow. For instance, they have been used for some time now on 30MW solar power plants in France and on grid connected Solar Arrays in Australia, producing as little as 250kW. These interconnects are much smaller than the Gigawatt connections of a large power plant, hence the need for a smaller RTU.
Conversely, smaller power plants can have a more complex set of communications demands, so the RTU’s needs to be ‘smarter’. For example. small sites are often independently owned and managed and must share data to numerous “masters”, like asset owners and investors, and contracted maintenance crews, in addition to the grid operator.
When it comes to smaller sites, TBox RTU’s are both the site controller and the site communications gateway. The RTU collects data directly, or provides a secure VPN, to PLCs used for solar panel tilt and azimuth control, to weather stations and to digitally networked power relays.
The collected data is then made available to the grid operators who can issue commands back to the RTU to regulate the station. In parallel, the RTU relays key information to the asset owner or investor and to maintenance crews.
With its ability to report alarms and historical data via email, SMS and FTP, it is the ideal choice for small power plants that need to manage both physical assets and wider communications demands.
Another area of application for smaller, smarter RTU’s are far-flung communities around the world that rely on small diesel generator sets for their power and using manual and often irregular monitoring schemes.
With a growing focus on the environment, RTUs are now being added to monitor not only genset status, but also emissions. In Asia, our RTU technology monitors diesel generator systems 24/7, providing emissions data to a central reporting system.
The centralised data can be accessed by the wider community through an Air Quality Index app on smart devices as a means of keeping their energy providers in check.
In addition, for the benefit of the owner, the RTU’s monitor the generator health, by tracking exhaust temperatures, heater exchange throughput and oil quality as part of proactive maintenance measures. Monitoring fuel use also benefits efficiency management and deters fuel theft.
Management of smaller power networks
Power distribution is not limited to the main power grid. Any facility where power is provided to must reticulate that power. Large, geographically dispersed facilities, like hospitals, universities, airports and railway lines have their own internal power network that needs management.
They have the same control and communications requirements as the main grid, at marginally less complexity. These facilities are typically critical assets that must always remain operational, so reliability and resilience to faults are key requirements of any equipment.
A specific example is an electrified railway network that source their main supply from the grid and then distribute that power throughout the estate. The rail network is almost as geographically dispersed as the power grid, covering the same territory, but following only the railway lines rather than every street and laneway.
The demands on RTUs used in this Railway Network has similarities to a Power Network RTU. They are exposed to remote environments, risk faults that expose them to high voltage spikes, must be able to store, manage and report large volumes of data and above all else, control the local switchgear.
Kingfisher RTU’s are meeting the geographic challenges presented in Australia by monitoring and controlling railway facilities. They are also used for railway power track applications where they operate in environments from -40°C to +85°C, with up to 5,000V isolation on external connections, meaning they will survive anything that the Railway Grid throws at them.
Even when a fault occurs, the RTU can be deployed with dual CPU’s, dual power supplies, an integrated UPS and multiple communications links on a mixture of media. This ensures that no single failure will take down the RTU and that monitoring and control of power on critical railway lines can continue all day, every day.
The physical environment is not the only threat against RTUs. Equipment that monitors and controls critical infrastructure must also be cyber secure and able to resist attack vectors in the digital sphere.
This is of greater importance for remote units where communication links leave the physical security of the plant and often utilise or share bandwidth on public networks. In order to overcome this, RTUs must be certified to Achilles Level 1, whilst we are also currently working towards IEC 62443 certification.
Monitoring and control at The Edge
A trending theme in modern information management is to push some of the data management back out to the field. Centralised data collection and analysis is vital for long term trend identification and planning, but a localised response is required for low latency control.
If you need a field hardened PC, or “edge computer” for monitoring electrical current, temperature, emissions, power and asset health, then you need an RTU.
RTUs are specifically designed to gather and relay information to SCADA or the cloud where it can be analysed and trended, providing operators with a high degree of predictive maintenance capabilities.
RTUs are also autonomous and can enact local control algorithms under the supervision of central operators. In remote locations, or during emergencies when communications systems are under pressure, fail or limited by a denial of service assault, RTUs can maintain local control and historical data storage.
Centralised control is helpless when remote locations are isolated due to a communications outage. RTUs add resilience to the control network by moving the real time control locally where it cannot be impacted by threats to the remote communications links.
RTUs are particularly suited for deployment across a diversified energy sector because they have the capacity for remote monitoring and autonomous control, are resilient to the site environment and can communicate to all interested parties.
As the energy sector grows and increases in complexity through more connected assets, managing them will require smarter solutions.
Latest RTUs are ideal for new entrants who are demanding ‘smarter’ information in order to achieve uninterrupted supply and maximise returns.
Traditional RTUs used in the primary electricity grid are often overly feature rich and therefore not suitable for a more diversified energy sector. Increasingly, operators are looking for smaller, smarter RTU solutions.
This article was featured on Process Industry Informer.