The article discusses and analyzes the operation of an autonomous electrical complex of a drilling rig in an emergency mode, namely when the supply voltage drops. The concept of voltage drop is also described, a comparative characteristic of technical devices and methods of overcoming voltage drops, indicating the disadvantages and advantages, is given. Modeling of an autonomous electrical complex of a drilling rig is performed in the MATLAB Simulink software package with a description of the parameters of the main elements. The voltage drop is achieved by a sharp increase in the load power consumption, which in reality is achieved by the drilling rig head getting stuck in the hard layers of the earth’s surface. As a result, there are graphs of changes in the voltage value at the terminals of the electric motor of the drilling rig, depending on the magnitude of the load. Based on these graphs, we can conclude that with an increase in load, the autonomous system does not have its own reserves and power reserves (and according to regulatory documents, this margin is 20%) in order to overcome the voltage drop and return it to acceptable values for further uninterrupted operation. As a conclusion, we can say that today the only optimal option in terms of material costs and technical features is to connect a backup diesel generator connected in parallel to the main one and having a comparative power.

The paper discusses the possibility of low-impendance (combined) neutral grounding in the 10-35 kV air network, suggests the logic of the relay protection against single-phase ground faults, and also based on computer simulation of transient processes, the potential of the low voltage network is estimated depending on the current circuit to ground, resistance values of the grounding device and network configuration 0.4 kV. The study is carried out by modeling the real part of the power system of St. Petersburg and the Leningrad region, located in the north-east of the region. Directly considered the distribution network of 110 kV Substation Plodovoe (Substation №. 511).

THE PURPOSE. To analyze scientific and technical information and practical experience of the functioning of autonomous electrical complexes with asynchronous electric motors in the composition. To develop a mathematical model of an autonomous electrical complex of a drilling rig with the presence of an active rectifier, an inverter with pulse-width control signals, as well as combined backup power sources – a battery and a diesel generator set. To establish the influence and expediency of using a combined composition of backup power sources on reliable operation and the possibility of overcoming the voltage failure caused by a sharp increase in load in the steady-state operation of an autonomous electrical complex. METHODS. For the successful fulfillment of the tasks set, this study applied the methods of mathematical modeling of power supply systems, methods of simulation modeling, the theories of automatic control, automated electric drive, and electrical circuits. Also, in research used the MATLAB software package with the built-in Simulink graphic modeling environment to create a mathematical computer model and to process the data obtained analytically. RESULTS. The article describes the relevance of the research topic. The study provides criteria for choosing the composition of backup power sources. Mathematical and simulation models of an autonomous ETC have been developed according to the “power source-frequency converter-industrial load” scheme, taking into account the influence of a non-linear load on the specified power quality indicators. The study has developed the structure of an autonomous electrical complex with a combined composition of backup power sources, which allows to overcome the voltage drop in the network caused by a sharp load surge, while ensuring the required indicators of electricity quality. CONCLUSIONS. The use of a rechargeable battery makes it possible to increase the overload threshold of the main diesel generator set regulated by GOST R 53987-2010 from 30% to 60%, as well as to ensure reliable connection of a backup diesel generator set without interrupting technological processes.

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