Thanks to modern high speed IGBT technology and real-time control strategy, Merus STATCOM provides excellent flicker reduction. For example in electric arc furnace applications, flicker can be reduced to 5.5. In addition to reactive power support, Merus STATCOMs also provide real-time active harmonic filtering for the mitigation of harmonic distortions caused by variable speed drives and for load balancing in unbalanced loading conditions.
Merus STATCOM can be overloaded for short periods of time, say for a couple of seconds per minute. This ensures high performance in applications where instant short period reactive power compensation is needed. Overloading capacity is defined by the size of the energy storage and the thermal limits of the semiconductors.
Merus STATCOMs are extremely redundant and modular systems. They are designed to operate as stand-alone units, and power can be increased by parallel connection of the systems. Merus STATCOM can be built with modules of different rated power and voltage to optimize the system for specific customer requirements. Each module has its own cooling system and an independent controller that communicates with the HMI. In case a module suffers an internal failure, it will be disconnected, and the remaining modules continue to operate without interruption. Fixed capacitor banks can be used when inductive reactive power demand is less than capacitive.
The Control and Protection system of Merus STATCOM is equipped with an advanced user interface and a 19” easy-to-use touch screen panel. Proven control algorithms with closed and open loop strategies enable effective and fast flicker mitigation and reactive power and power factor control along with harmonic mitigation.
Merus STATCOM can be understood as a controlled current source connected in parallel with the load to be compensated. It can produce both capacitive and inductive reactive power thanks to its ability to vary the phase angle and the magnitude of its output current dynamically. Merus STATCOM responds instantly to changes in the reactive power demand of the load it is set to compensate and thus ensures that reactive power supply from the power grid is kept at the minimum.
The main components of the Merus STATCOM system are DC link capacitors, high frequency semiconductor switches and a filtering circuit. The DC link capacitors are the source of reactive power. The multilevel IGBT bridge uses the energy stored in the DC link to produce any kind of current waveform at the STATCOM output with fast IGBT switching. The brain of the system is the Modular Controller Concept (MCC) that measures the network current, separates the reactive and harmonic components and controls the IGBTs according to the assigned compensation settings. Merus STATCOM can be connected either in open-loop or in closed-loop configuration.