the harmonic index h(g) , of a graph g is defined as the sum of weights 2/(deg(u)+deg(v)) of all edges in e(g), where deg (u) denotes the degree of a vertex u in v(g). in this paper we define the harmonic polynomial of g. we present explicit formula for the values of harmonic polynomial for several families of specific graphs and we find the lower and upper bound for harmonic index in caterpill...

The soft-switching characteristics of double-sided LCC wireless power transmission systems are susceptible to system parameter disturbances. In order improve the stability zero voltage switches in constant-current and constant-voltage charging modes, this paper synthesizes eight resonant conditions which make realize constant-current/constant-voltage Zero Phase Angle. influence compensating cap...

High impedance faults (HIFs) detection in overhead distribution networks have been a major challenge for utility engineers long time. The current flowing to ground path is so low that conventional protection does not detect HIFs. problem becomes more critical when HIFs occur rural feeders with many single-wire earth return networks, since the neutral usually set above normal unbalance of circui...

this paper presents a new control methodology for active power filters that provide an adaptive online harmonic estimation with partial and selective harmonic reduction schemes, which has been implemented within an integrated controller. the proposed approach is to provide partial and selective reduction of those individual harmonics which exceed the recommended levels as set by regulatory bodi...

Star-point reactors are grounding devices installed in HVDC stations between the converter transformer secondary side and AC of arms to provide a reference ground. Such used as high-impedance on power transformers, providing high impedance path for fundamental harmonic (i.e. 50 or 60 Hz) low DC current, eliminating current flowing through windings. Temperature rise capability tests 420 kV star-...

After microgrid transition from the normal operation to the islanded operation the system impedance changes considerably and it affects on the harmonic voltages of the microgrid. In this paper the voltage and current THD before and after islanding are studied with different microgrid configurations. Simulations are also made by applying negative sequence filtering in control system of converter...