With the new system, Safari Lodge meets most of its energy demand with the solar power system, which produces a total of 300 kWp. 260 kWp rooftop systems have been installed on the carports and the employees' accommodation (image 1). On top of this, 40 kWp is produced by three dual-axis trackers (image 2). They feed the lithium-ion storage with a capacity of 1,027 kWh (image 3), which in turn supplies the grid-forming, bidirectional battery inverter. With a peak output of 250 kW at stable output voltage and frequency, it provides ample reserves for a 3-phase power supply. Even larger consumers, such as cooling systems, engines or the charging stations for the Land Cruisers, can be reliably operated using this system. The inverter and batteries are housed in a 20-foot energy container. It has been equipped with air-conditioning and an extinguishing gas system and was delivered fully wired.
A 150 kVA diesel generator is used for emergency power supply. The generator was upgraded from a stand-by generator to a generator that can be controlled remotely and is suitable for parallel operation. However, it is only used in exceptional cases. The system runs on almost 100% renewable energy. In addition, the regional energy supplier's single-phase line can also be connected.
Electricity does not come "from the socket", from the grid, everywhere in the world. And it isn’t only in settlements in the middle of nowhere or raw material extraction far from civilization. Remote holiday resorts need electricity too. Until now, this was provided by diesel generators - noisy, polluting and increasingly expensive. But there are hybrid solutions that use renewable energy to drastically reduce or even completely replace diesel consumption. It is made possible by a combination of energy management and measurement technology.
Luxury resort is an incomplete description of Cheetah Plains Lodge in South Africa. Guests who book a safari here stay in villas with their own wine gallery, curated art collection and, of course, a private chef. The tour goes off-road under expert guidance with electric Land Cruisers; a quiet and emission-free form of transport that almost guarantees Big Five sightings.
However, a unique safari experience is not the only thing that the house management and the discerning guests value. Environmental management and sustainability are also a must. This includes grey water recycling and using construction materials such as energy-saving glass, which reduces heat transfer through the windows.
One problem still had to be solved: obtaining a sustainable and secure power supply. Although there was a single phase connection from the local energy supplier, the capacity was limited and there were considerable voltage fluctuations. This type of supply was unable to cope with the increasing energy demand from cooling systems and charging stations for the e-vehicles. Therefore, the owners commissioned the South African solar power expert Blockpower and the German microgrid integrator Dhybrid to install a three-phase energy system with a photovoltaic plant and a microgrid energy storage system based on lithium-ion batteries. A diesel generator only needs to cover possible supply shortfalls in case of an emergency.
In the past, the power supply in microgrids was almost exclusively supplied by robust and easy-to-maintain diesel generators. However, these no longer satisfy the demands of the operating conditions in modern systems. This is partly due to environmental pollution and rising fuel costs, and partly due to the power quality requirements, and this not only in luxury resorts. Energy-hungry incandescent lamps have also been replaced by LED panels in the staff quarters at remote production sites. And of course there are flat-screen televisions, notebooks, smartphones and machines with embedded PC controllers. Photovoltaic systems with battery storage and possibly a diesel as a backup are increasingly in demand here. Dhybrid Power Systems GmbH from Gauting specializes in hybrid smart grid solutions of just this kind. The product range includes a customized energy management system (EMS) - the Dhybrid Universal Power Platform (Dhybrid UPP) - which can combine a wide variety of technologies, such as battery storage, photovoltaic systems and wind power plants, no matter the manufacturer. Dhybrid also offers turnkey battery energy storage systems (Bess). To monitor and optimize the power supply quality, Dhybrid uses Janitza electronics GmbH's energy measurement technology and active power filters. Monitoring power quality is essential, especially in microgrids with high grid impedance.
Energy sources are plentiful at the lodge: Sun, the local grid, the battery, diesel as a buffer... There is no risk of the guests suddenly sitting in the dark or the Land Cruisers not running - provided the energy flows in the right directions. This is taken care of by UPP, short for Universal Power Platform. This energy management system was developed by Dhybrid specifically for smart grid control. The intelligent control platform provides full transparency and control over the whole energy system. It monitors all the network parameters as well as the power generators' active and reactive power reference values. This means that the system can be operated automatically.
Unlike many conventional microgrids, where either the diesel or the photovoltaic system runs at any one time, the Dhybrid UPP can control different generators simultaneously and in coordination with each other. This means that the diesel generator only needs to be switched on during periods of exceptionally high energy consumption or during bad weather. Tom Fricke, who manages the energy storage and sales division at Dhybrid, pointed out another advantage: "Our system is open to all technologies, which means we can connect equipment from a wide range of manufacturers. Since we can use all components, we can act very proactively. This is true, for example, for the service life of batteries. Different operating conditions cause them to age faster or slower. Because we know how the load or photovoltaic generation evolves throughout the day, we can optimize the operating strategy to make the battery last longer.”
Realtime monitoring and remote maintenance of the network are carried out by VPN using a SCADA system from Dhybrid. Additionally, the UPP offers access to historical data, reports and dashboards through a web portal.
Having a quick overview of the essential functions and the operating status of the system at all times is indispensable for the crew on site. On the other hand, the specialists at Dhybrid need more detailed information for remote maintenance. With the measurement devices from Janitza, both are possible. Alexander Wagenhuber from Janitza explained: "Unlike many other devices on the market, we offer four ports, sometimes even more. This makes communication with several systems easier. This way, Dhybrid's SCADA and our GridVis software can even access a meter at the same time." Tom Fricke added: "GridVis is a good tool, especially for initial commissioning. You can quickly see whether the measured values fit and can log them as well. The larger devices even have a dedicated webpage, which we use to generate power quality reports in addition to event logging." As a result, Janitza's hardware and software have made it possible to implement two independent measuring systems. Technicians on site receive all the necessary information for operations and servicing. In addition, the specialists at headquarters in Gauting can connect remotely and give guidance on tricky work. The combination of the UMG measurement devices from Janitza and the corresponding GridVis software allows a much higher data transmission rate than a SCADA system.
The total solution offers Cheetah Plains a whole range of advantages, including the integration of 3-phase consumers, increased peak power supply and a stable system voltage and frequency. Independence from the grid does not come at the expense of nature. Guests and hosts can enjoy the fact that the power supply provided for their comfort and to allow them to travel around is generated directly on site using solar energy.
Precise measurements are required for the elaborate energy management system. These are carried out using the measurement technology specialist Janitza’s devices. Tom Fricke explained why: "Janitza is high-quality measurement technology from Germany. We have been using it in a wide variety of projects practically since we were founded. Their portfolio ranges from very economical devices up to A-class equipment. This means we have a solution for every requirement. Also, the service is always very quick to respond."
In the first few projects, standard devices such as the UMG 96RM-EL were installed. But these may no longer be sufficient for systems with particularly high energy efficiency, because they predominantly use non-resistive loads. Since microgrids naturally have a comparatively high impedance, the effect of harmonics and comparable phenomena is much stronger than in large, public networks. High-quality measurement technology is especially important here. For this purpose, Dhybrid uses multifunctional UMG 509 and UMG 512 network analyzers (image 4). "We were able to detect harmonics with it, but also unbalances on the load side, which can lead to voltage deviations," Tom Fricke explained. This can lead to problems in unfavourable cases. For example, when the vehicles are charged in the evening, LED panels go into operation, and at the same time the guests want to view the photographs they took that day on their own cameras and tablets without interference. High harmonic content can significantly shorten the service life of these electronic consumers. To avoid any interference from the outset, Tom Fricke supplemented the lodge's energy supply with an active filter from Janitza: "With the active filter, we can once again improve the power quality and at the same time compensate for load imbalances," he explained. No additional maintenance is required. Once the active filter has been configured, the system runs automatically.