978-1-5386-0517-2/18/$31.00 ©2018 IEEE. Network Resonance Detection using Harmonic Active Power Agknaton Bottenberg 1 ,Colin Debruyne 1, 3 , Brandon Peterson 2 , Johan Rens 2 , Jos Knockaert 1 , Jan Desmet 1 1 Electrical Energy Laboratory, Ghent University, Sint-Pietersnieuwstraat 41, B-9000 Ghent, Belgium 2 School for Electronic and Electrical Engineering, North-West University (NWU) Potchefstroom Campus, X6001 Potchefstroom, 2520 South Africa 3 Advices for Technical Systems div. Power Quality, Karel De Roosestraat 15, B-9820 Merelbeke, Belgium Abstract—Resonances in electrical distribution systems can result in amplification of harmonics, which is undesirable in electrical networks. To avoid intrusive measurement techniques, in the majority of the cases network modeling is used to validate if there is an issue with resonance. In this paper a new, innovative but simple, concept is presented which uses relatively basic measurements to segregate the power related to specific harmonics into active and non-active harmonic power. These results are subsequently used in order to find if there is resonance in the electrical network. In this paper the concepts are explained on a theoretical basis and are test cased by numerical modeling. The initial results look promising but additional research is needed to validate the method. I. I NTRODUCTION With the increased penetration of power electronics, both from electrical loads and generators, the network is additionally strained with harmonic content. When focussing on the problems related to harmonics in networks, they negatively affect the life expectancy of the insulation in the network, generate additional losses in transformers and might damage active capacitor banks [1]–[3]. Because networks consists of inductances, capacitance and some resistance, there is always resonance in the network. Practical problems arise at the moment the resonance amplifies the distortion in either voltage or current. Therefore it is of great concern to determine the network’s impedance over frequency characteristic to evaluate if there is an issue related to harmonic resonance. In the majority of the cases this is estimated at the design stage of the network and done via modeling in dedicated software. In situ monitoring of those impedance over frequency plots is essential for stable operation, but this generally requires intrusive methods. There have been some suggestions of algorithms to try to obtain this data based on measurements using non-intrusive techniques [4], [5]. This proves to be promising, although the long iterative process requires a lot of time. In a practical setting the previous methods are facing practical disadvantages as the network’s impedance is varying due to switching actions and reconfiguration of the network by the network operator. In this paper a basic measurement method is suggested to perform a real time detection of resonance phenomena in the network based on the power related to individual harmonics. The basic concept, including its limitations, is mathematically explained in §II and §III. Subsequently, this method is used in a numerical model to testcase the validity §IV and the results validate the suggested method. Although the results of the modeling indicate that the proposed method has potential, this method does also has constraints. As will be addressed in the paper, the suggested method can bridge the gap to the more complex analysis of the prevailing harmonic phase angle, however this research is specifically focussed on finding a very basic, low level, method for an indication of resonance. As will be discussed in §V, much more validation is needed. II. BASIC ANALYSIS OF RESONANCE PHENOMENA In electrical systems, there is a resonance if the reactive power component in the inductor is equal and opposite to the reactive power component in the capacitor. When written in terms of reactances, resonance occurs if: X l = X c (1) With X l the inductive reactance and X c the capacitive re- actance. For electrical distribution systems the reactance is depending on the frequency, so resonance occurs for specific resonance frequencies f r in which: f r = 1 2.π. √ L.C (2) With L the inductance in [H] and C the capacity in [F]. Two types of resonance can occur, namely parallel resonance and series resonance. Fig. 1. [A] Parallell resonance with ESR, [B] Series Resonance In case of parallel resonance the impedance goes from zero to -theoretically- infinite, and then back to zero. Subsequently, in case of series resonance, the impedance goes from highly