Motivation and background, Project Goals

Uninterruptible power supplies (UPS) are used in critical areas (e.g. IT) to protect against (short-term) power failures. These battery storage units are nowadays only used a few times a year and are otherwise idle. The aim of this project is therefore to harness the considerable potential of synergetic effects of the UPS system in the context of intelligent micro- and smart grids in order to contribute to a sustainable and economical energy supply. The necessary industrial research of this hybrid UPS system is the task of the project.

Fig. 1 shows an abstraction of a company network. This includes facilities for power generation (wind turbines, photovoltaic systems, combined heat and power generation and a diesel generator), various categories of loads (divided into non-critical, economically critical and critical loads) and a hybrid UPS system. Compared to a conventional UPS, this should be able to supply both critical loads and economically critical loads in the event of a grid failure. While for critical loads the power supply has the highest priority, economically critical loads can still be supplied at least for a certain time in the event of a power failure. If the public grid is available, the storage is used economically. With the hybrid UPS, this includes avoiding high energy costs, especially at peak loads, by ensuring that the UPS system contributes a certain amount of energy to reduce mains current peaks at the point of common coupling (PCC). This can be achieved, for example, by so-called peak shaving. The economic benefits also include the provision of primary control power (through the interconnection to a virtual power plant) and the increase in own consumption (intermediate storage of self-generated power).

The advantage of a hybrid UPS lies in reduced energy bills and at the same time higher security of supply for non-critical loads.