One of the most essential tasks for a number of systems of the automatic controls in the autonomous electric power systems of the water transport is accurate calculation of variable harmonic components in the non-sinusoidal signal. In the autonomous electric power systems operating with full semiconductor capacity, the forms of line currents and voltages are greatly distorted, and generator devices generate voltage with inconsistent frequency, phase and amplitude. It makes calculation of harmonic composition of the distorted signals be a non-trivial task. The present paper provides a mathematical set for solution of the outlined problem including the realization in the discrete form. The simplicity and efficiency of the system proposed make possible to perform its practical realization with the help of cheap FPGA. The test of the developed system has been performed in the medium Matlab. The modern ship's electric power systems (SEPS) are characterized by the presence in its composition of a great number of the conversion load, including frequency transformer, un-interruptive power supply, inverters, rectifiers and other consuming devices varying in their non-linear volt-ampere features. Similar load has a negative impact on the supplying network of the alternating current, generating into it highest harmonic components of currents and voltages. At the same time, a great deal of the ship's automation systems apply the line currents and voltages to form the reference signal. Thus, for example, an automatic voltage regulator (AVR) of the ship's synchronous generators (SG) performs regulation by an average value of voltages and currents in the circuit. However, with the distorted form of the variable signals (that is caused by the presence of a wide range of highest harmonics) their average value increases and an automatic voltage regulator (AVR), correcting the error, decreases the exciting current of the synchronous generator that results in loss of voltage in the ship's electric power systems (SEPS). Consequently, decrease in relative value and increase in highest harmonics take place, and, thus, the electromagnetic moment of the non-synchronous motors decreases, the level of interferences influencing the systems of the ship's automatic controls becomes higher, and the losses in the power supply lines enlarge. Practically, such an error is corrected by the adjustment of the voltage corrector (VC). However, as the harmonic composition periodically varies depending on the mode of operation and the composition of the load of the electric power station, the setting of the voltage corrector should be changed constantly. This problem should be solved by measuring the level of the basic harmonics of the current and voltages of the ship's circuit. On the other side, it is known that filter-compensating devices (FCD) are the most efficient means to increase the quality of electric energy in the ship's power supply systems at the moment. Their efficiency in higher harmonic suppression and compensation of their volt-ampere reactive may be provided only by the high accuracy of the calculation of parameters in the target harmonics of the line currents and voltages. 2. Settlement of the problem Thus, the required functional set of the systems taken as an example determining their efficiency, in particular, and their operational performance in general, is a set for identification of external parameters of the control system. The major function of the block is extraction of harmonic components required for their analysis, calculation of their parameters from the distorted signal and application of the results of that analysis in the control of the means of the increasing values for quality of the electric
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