DIAGNOSTIC MODELS OF ACCIDENT STATES OF POWER BLOCKS OF ELECTROTECHNICAL SYSTEMS
In this paper a block model of power blocks of electrical engineering systems is obtained, which operates with a set of models of subsystems of separate units, nodes and elements of electrical engineering systems. The object of diagnosis is divided into functional blocks, with the accuracy of which the search for defects is carried out. The rectifier and inverter are considered as the main diagnostic elements of the power circuits. Thanks to the analysis of the diagnostic model of the rectifier, first of all, it was estimated what volume of diagnostic information is needed for the full operation of the model. As a controlled parameter, the current of the thyristor was selected, since the diagnostic model is based on the use of current sensors that flow through the power valves. It is established that for complete diagnostics it is enough to control current in phases and current in the power circle. Depending on the distribution current in the circuit, all modes of operation are divided into: operating state, short-circuit condition, when the current flows simultaneously on both shoulders of the bridge, the condition of the break of the valve. Each state is described by the corresponding equation. It is also established that for the diagnosis it is necessary to control the currents in the shoulders of the inverter bridge. The obtained results allow to determine the location of sensors in the converter circuit that control the state of the converter. According to the data obtained, it is necessary to install sensors measuring the currents in each phase of the rectifier, current in the circle of power and currents flowing through the power valves of the inverter. The developed diagnostic models of the states of power blocks and the general diagnostic model of the states allowed to determine the minimum set of diagnostic signs and the point of removal of diagnostic information.