This July on our blog we talk about the power control systems. We have interviewed Adolfo Ausín, Head of Power Electronics at Norvento. We have been talking about microgrids, their management and aspects to take into account in their assembly.
What is a microgrid and what are its components?
A microgrid is an electric grid that includes elements of energy generation and consumption and that is also isolated from any other electric grid. CIne is a good example of it: the building’s electric grid is isolated from the Spanish electric grid and includes energy generation (wind, solar) and consumption (lighting, kitchen, cooling and heating systems, etcetera).
In general terms, the most interesting thing about micro-grids are the elements capable of generating energy. The consumptions are easy to imagine. There are two types of devices capable of producing energy: those that work using renewable sources (photovoltaic panels and wind turbines, for example), and those that use fossil fuels (such as generators powered by diesel engines). The problem that microgrids have to solve is that they must adjust the generation to the consumption under the restriction that the renewable energy´s availability is variable and unpredictable. At times of high renewable production, it is possible that the generated energy exceeds the consumed energy. And vice versa, it may happen that at certain times more energy is consumed than what is being generated. The first case could be solved by limiting the generation. The second case can only be solved either by connecting the generator set or by storing energy when there is excess of production and reusing it later. To avoid such polluting fossil fuels, batteries are used because they can efficiently store the surplus of electrical energy. There are other methods (such as those related to hydrogen), but today none is as profitable as batteries.
How is it managed?
The system must be provided with an “intelligence” able to govern the logic of all possible transitions. This logic is often called the Power Management System (PMS). Normally an industrial computer or similar receives data on the state of the different elements and the measurements of electrical quantities of the installation. According to how it was programmed or the indications it would receive from a higher entity, it must execute the orders that optimize the operation of the system. For example, it has to keep the battery between certain safe charge levels, decide when to start, stop or limit renewable production, select whether to activate or stop emergency systems, disconnect non-essential loads, etcetera.
What aspects should be taken into consideration when setting up a microgrid?
First of all, what should be clear is the consumption profile of the installation. Then, based on the geographical characteristics of the site, should correctly choose the renewable power to be installed. It is just like the power contracted at domestic level, which must always be higher than the one that is going to be consumed. Factors like solar radiation throughout the year, the usable surface for solar panels, the orientation and shadows, the available wind or the energy autonomy needed serve to dimension the installation correctly.
And of course, the economic aspects – magnitude and return on investment – have to be prioritized in order to make it attractive.
Norvento’s Power Electronics team has developed the Norvento Gridmaster Converter. Can you tell us a bit more about it? What applications does it have?
The Norvento Gridmaster Converter (nGM) is a device designed and manufactured entirely by Norvento. It that has two main objectives:
- To manage the charging and discharging of batteries while forming the electrical grid,
- To assume the logic of the microgrid control.
In practice, it looks like a normal electrical cabinet, with certain cooling needs. Inside it houses power electronics components (semiconductors, capacitors, inductors, transformers and electronic measurement and control cards) that work with high voltages and high currents in an environment with a high density of electromagnetic radiation. A family of converters has been developed consisting of three similar units, although with different power (50, 100 and 200 kW). They are already in the commercialization phase and the first units have been installed in rural industries in Galicia and Valencia. We can observe remarkable achievements: farms isolated from the electricity grid that used only diesel groups all year round, now thanks to a small investment in solar panels, in a nGM50 and in a small battery are being supplied with 70% renewable energy. In a short time, they will recover the initial investment and then the energy will be less expensive.
The renovation of the CIne facility, completed these days, is possibly the one with the most merit from a technical point of view. It has been carried out thanks to the work and collaboration of different departments of the company. From now on, all the energy and electronic technologies in the building are 100% Norvento’s own developments. CIne’s micro-grid is much more complex than those previously executed as there are many more generation elements to coordinate, there are highly demanding electrical consumptions (large groups of motor-compressors) and it also allows automatic connection and disconnection to the electrical grid without loss of supply. We hope that this effort will contribute to the maturity and projection of the nGM as part of the company’s commitment to clean and sustainable energy solutions.
Do you want to know more about the Norvento Gridmaster converter? Visit our website.
