-
Date submitted2020-06-15
-
Date accepted2020-06-15
-
Date published2020-06-30
Multi-terminal dc grid overall control with modular multilevel converters
This paper presents a control philosophy for multiterminal DC grids, which are embedded in the main AC grid. DC transmission lines maintain higher power flow at longer distances compared with AC lines. The voltage losses are also much lower. DC power transmission is good option for Russian north. Arctic seashore regions of Russia don't have well developed electrical infrastructure therefore power line lengths are significant there. Considering above it is possible to use DC grids for supply mining enterprises in Arctic regions (offshore drilling platforms for example). Three different control layers are presented in an hierarchical way: local, primary and secondary. This whole control strategy is verified in a scaled three-nodes DC grid. In one of these nodes, a modular multilevel converter (MMC) is implemented (five sub-modules per arm). A novel model-based optimization method to control AC and circulating currents is discussed. In the remaining nodes, three-level voltage source converters (VSC) are installed. For their local controllers, a new variant for classical PI controllers are used, which allow to adapt the values of the PI parameters with respect to the measured variables. Concerning the primary control, droop control technique has been chosen. Regarding secondary level, a new power flow technique is suggested. Unbalance conditions are also verified in order to show the robustness of the whole control strategy.
-
Date submitted2019-03-31
-
Date accepted2019-08-25
-
Date published2020-02-25
Cascade frequency converters control features
The structures of systems with high-voltage cascade frequency converters containing multi-winding transformers and low-voltage low-power converters connected in series at each output phase of the load are considered. Low-voltage blocks contain three-phase diode or active rectifiers, DC capacitor filters, single-phase stand-alone voltage inverters and block disconnecting devices in partial modes (in case of failure when part of the blocks are disconnected). The possibilities of operation of cascade converters are determined, equations for correcting tasks to units in partial modes are given, tables of correction of tasks with estimates of achievable load characteristics are proposed. The results of experiments on the model of a powerful installation with a cascade frequency converter are presented, confirming the possibility of ensuring the symmetry of the load currents when disconnecting part of the blocks and the asymmetry of the circuit.
-
Date submitted2019-07-07
-
Date accepted2019-09-13
-
Date published2019-12-24
Installation for experimental research of multiphase electromechanical systems
- Authors:
- V. M. Tereshkin
- D. A. Grishin
- I. A. Makulov
The subject of this study is an installation for experimental research designed to study the characteristics and control algorithms of multiphase motors with the number of working phases from 3 to 8, connected by a star, a triangle, or in another way, allowing phase currents to flow, creating a rotating electromagnetic field. The installation consists of two separate independent units: a controller, or a human-machine control interface, and a power inverter module (converter). The controller is connected to the converter by a two-wire half-duplex interface (RS485) via the Modbus RTU communication protocol. The installation also includes synchronous motors with the number of phases 3, 5, 7. Using the developed installation for experimental research, it is possible to carry out experimental studies of multiphase motors when implementing various control algorithms for a converter that implements pulse-width vector modulation. The time required to implement control algorithms is minimal. According to the results of the experiments, it is possible to carry out a comparative analysis of multiphase motors in terms of energy efficiency, in terms of vibration of electromagnetic origin, in dynamic parameters. An experimental assessment of the load of the converter keys is possible. The created installation is an effective tool for checking the reliability of the results of theoretical studies of electromechanical systems based on multiphase motors.
-
Date submitted2010-07-26
-
Date accepted2010-09-14
-
Date published2011-03-21
Algorithm of control of the electric drive with ventilniy electric motor and the converter of frequency with the active rectifier
- Authors:
- A. P. Emelyanov
- A. O. Sviridenko
Advantages of application of the active rectifier as a part of converters of frequency for powerful drives with ventilniy electric motors are considered. The mathematical description of the processes proceeding in a power part of the active rectifier is given. The scheme of a drive with a vector control system with the gage of position of a rotor and the active rectifier is presented, schedules of power consumption and a current by a drive with the active rectifier are resulted.
-
Date submitted2010-07-08
-
Date accepted2010-09-02
-
Date published2011-03-21
The autoresonant asynchronous electric drive of dynamically counterbalanced drilling string on carrying cable with swinging movement fluctuations amplitude stabilization
- Authors:
- E. A. Zagrivnyi
- V. V. Ivanik
The algorithm of resonant fluctuations amplitude stabilization of dynamically counterbalanced drilling string on carrying cable with swinging movement of jackbit is developed. Imitating modeling of the resonant asynchronous electric drive with swinging movement of jackbit with the frequency converter in various operating modes is resulted.
-
Date submitted2010-07-20
-
Date accepted2010-09-14
-
Date published2011-03-21
The physical breadboard model of dynamically counterbalanced drilling string with swinging movement with the asynchronous electric drive powered by inverter laboratory experimental researche
- Authors:
- V. V. Ivanik
The laboratory experimental stand for research of the asynchronous resonant electric drive on a physical breadboard model of dynamically counterbalanced drilling string is developed. The asynchronous electric drive with swinging movement the autoresonant oscillation mode is realized.
-
Date submitted2010-07-06
-
Date accepted2010-09-14
-
Date published2011-03-21
Electromechanical processes in electric drives of mountain equipment on the basis of the synchronous electric motor
- Authors:
- A. O. Sviridenko
The description is given and the function chart of the bench installation is resulted, allowing to reproduce static and dynamic modes of adjustable electric drives of an alternating current. The modes considered during experimental researches of the electric drive on the basis of the synchronous electric motor, working in a mode of ventilniy electric motor are listed. Conclusions are drawn on character of course of dynamic modes, comparison of the electric drive to the synchronous electric motor and the electric drive of a direct current with the subordinated regulation is given.