With the application of the “Regulation on Supply Reliability and Quality in Electricity Transmission System” dated 10.11.2004, Reactive Energy Punishment Limits have been changed gradually, and as from the beginning of 2009, it turns out to be obligatory for electrical loads and electricity distribution systems to be operated at about 1.0 average capacity factor.

These new penalty limits will result in setting gradually more and more shunt capacitor banks in the Turkish Distribution System. When the distribution system is considered together with the transmission system, current harmonics to be injected by modern industrial loads can lead to the danger of parallel resonance in the whole system. At least, some harmonics can be subject to serious amplification. These harmonic overcurrents can cause transient or permanent damage in the Transmission System elements and shunt capacitor banks by reflecting directly on the Transmission System. The simulation works carried out with the use of typical distribution system single-line diagram have shown that parallel resonance frequency can fall to the 3rd -5th harmonic intervals. The 3rd current harmonic is also generated by all the standard loads, and it is regarded as a very dangerous current harmonic component in terms of parallel resonance event, since its unbalanced part will directly reflect on HV Network. In order to eliminate the parallel resonance danger in the low harmonic frequency; on one side, it is necessary that very strict rules should be established on the compensation practice which will be carried out on the MV side of the distribution system; on the other hand, an effective filtering should be made on the problematic points where the Distribution System is connected to the Transmission System.

Within the scope of this sub-project, a prototype will be implemented by carrying out research and technology development activities for a MV Active Power Filter System with 5 MVA installed capacity, which can be connected to a 36kV busbar by means of a coupling transformer. For this purpose, standard 1.0 MVA units will be developed, a 5 MVA capacity will be obtained by paralleling five of them, and this system will be connected to the most problematic point of the interface of transmission and distribution systems. Since MV Active Power Filter prototype consists of generalized 1.0 MVA standard units, it will be a modular and also relocatable system because it can be easily removed and connected to another point in the case the need at one point disappears. This Active Power Filter which can react rapidly will eliminate the negative effects of the harmonic currents on the Transmission System elements by damping one of the low frequency harmonic current components grown out of the Distribution System, which might cause parallel resonance event (3., 5. or 7. harmonic current components).

The concept of MV Active Power Filter is a recent concept in the world. Even though it is known that one or two implementations have been achieved only in Japan, there is no detailed information about these implementations. Therefore, MV Active Power Filter which will be developed by the project group will drastically contribute to the international literature as a unique system implementation.

Project Head: Alper Terciyanlı

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