RU144730U1 - HIGH VOLTAGE FREQUENCY REGULATED ELECTRIC DRIVE - Google Patents

Abstract

1. The high-voltage frequency-controlled electric drive contains an actuator, an electric motor, a transformer and a high-voltage frequency converter, characterized in that the high-voltage frequency converter with a voltage of 10 kV and a power of 2500 kW includes a multi-winding transformer and a multi-level voltage inverter, and the high-voltage frequency converter is installed in the unit -container and contains four cabinets: a multi-winding transformer cabinet, two multi-level voltage inverter cabinets and a cabinet braking resistors. 2. The high-voltage frequency-controlled electric drive according to claim 1, characterized in that the multi-winding transformer is a transformer of dry insulation class 10 / 0.69 kV, containing an assembled core with a single primary winding and 27 axially-separated secondary windings, and has built-in temperature sensors with a high voltage isolation. 3. A high-voltage frequency-controlled electric drive according to claim 1, characterized in that a controller is installed on the cabinet door of the multi-winding transformer with the ability to display the temperature of the transformer on the controller’s monitor. 4. A high-voltage frequency-controlled electric drive according to claim 1, characterized in that four tangential fans are installed in the lower part of the multi-winding transformer cabinet, and three axial fans with the possibility of providing air cooling are installed on the doors of the multi-winding transformer cabinet. The high-voltage frequency-controlled electric drive according to claim 1, characterized in that the multi-level voltage inverter is installed in two multi-level cabinets

Description

The utility model relates to the field of electrical engineering, in particular, to the areas of automated electric drive and converting technology and is intended to control the speed of asynchronous and synchronous electric motors (ED) of alternating current.

The prior art high-voltage frequency-controlled electric drives (hereinafter VFD) for a voltage of 6, 10 kV in the power range of 400-12000 kW series PChTE-TV company JB Plus s.r.o. (Baru A.Yu., Pedan EA, Popovsky V.A., Shindes Yu.L., Tverdokhleb I.B. “Frequency-controlled electric drive as a universal means of controlling pumping units.” Materials of the XIII International Scientific and Technical Conference "HERVICON-2011", September 6-9, 2011, Sumy State University, Sumy, Ukraine, pp. 1-19), made on the basis of an autonomous current inverter. The VFD includes input and output matching transformers, controlled rectifiers, smoothing chokes and autonomous current inverters. Performed on 12-fold or 24-fold pulse frequency of the AC rectification circuit.

The disadvantages of the analogue are increased weight and size and cost indicators of VFD.

High-voltage VFD with multi-level frequency inverters of the type Perfect Harmony WCIII by Siemens LLC (A. G. Ivanov, M. A. Shelyakhovsky, S. A. Fomin, “SIEMENS Modern Solutions in the Field of Powerful High-Voltage Electric Drives” is also known. Adjustable electric drive . Experience and prospects of application. Reports of a scientific and practical seminar, February 2, 2006., Moscow. - M.: MEI Publishing House, 2006, pp. 72-75) based on a multi-level voltage inverter. The high-voltage frequency-controlled electric drive contains an actuator, an electric motor, a transformer and a high-voltage frequency converter.

This analogue is closest in technical essence to the proposed utility model and adopted as a prototype.

The disadvantage of this analogue are:

- the inability to switch the motor power from the high-voltage frequency converter to the network and vice versa.

The objective of the utility model is to increase the efficiency of the high-voltage frequency-controlled electric drive.

The technical result is expressed in the use of a multi-level voltage inverter with an output voltage of 10 kV, to power an AC electric motor with a voltage of 10 kV and the use of a vector sensorless motor speed control system that provides the necessary accuracy of maintaining the speed of the electric motor.

The problem is solved, the technical result is achieved due to the fact that the high-voltage frequency-controlled electric drive contains an actuator, an electric motor, a transformer and a high-voltage frequency converter, and the high-voltage frequency converter with a voltage of 10 kV and a power of 2500 kW includes a multi-winding transformer and a multi-level voltage inverter, and a high-voltage frequency converter is installed in a block container and contains four cabinets: a multi-winding transformer cabinet, two cabinets fa multilevel voltage inverter and cabinet braking resistors.

A multi-winding transformer is a transformer of dry insulation class 10 / 0.69 kV, containing an assembled core with a single primary winding and 27 axially separate secondary windings, and has built-in temperature sensors with high voltage insulation.

A controller is installed on the cabinet door of the multi-winding transformer with the ability to display the temperature of the transformer on the controller’s monitor.

Four tangential fans are installed in the lower part of the cabinet, and three axial fans are installed on the doors of the multi-winding transformer cabinet with the possibility of providing air cooling of the multi-winding transformer.

A multi-level voltage inverter is installed in two cabinets of a multi-level voltage inverter, containing 27 power cells, each of the power cells of a multi-level voltage inverter is powered from the secondary windings of a 690 V three-phase AC voltage transformer and consists of a rectifier (semi-controlled), a filter (film capacitors) and a single-phase an inverter based on IGBT transistors, with the possibility of creating a 54-fold pulse frequency of the AC rectification circuit, and forming a smoothed sinusoidal form of current consumed from the network.

Tests of the developed high-voltage frequency-controlled electric drive with a voltage of 10 kV and a power of 2500 kW for 1057 hours in the absence of failures confirmed the high level of reliability and efficiency of the VFD. At the same time, it is characterized by ease of maintenance and operation.

The utility model is illustrated (Fig. 1 - Fig. 7).

In FIG. 1 shows a diagram of a high-voltage frequency-controlled electric drive for a voltage of 10 kV.

In FIG. 2 - power cell of a multilevel voltage inverter.

In FIG. 3 - waveforms of input / output currents and voltages.

In FIG. 4 is a functional diagram of a control terminal.

In FIG. 5 is a generalized block diagram of a vector control system of an induction motor.

In FIG. 6 is a functional diagram of a voltage vector-forming unit.

In FIG. 7 - waveforms of currents and voltages in the mode of synchronous transition to the network.

The following notation is used in the figures:

1 - power supply network 10 kV;

2 - multi-winding transformer;

3 - multi-level voltage inverter;

4 - electric motor.

A high voltage frequency converter with a voltage of 10 kV and a power of 2500 kW includes a multi-winding transformer 2 and a multi-level voltage inverter 3.

In contrast to the prototype, a 54-fold pulse frequency of the AC rectification circuit is used in the high-voltage frequency converter (in the prototype, only 36-fold), which allows you to form a smoothed sinusoidal shape of the current consumed from the network.

A high-voltage frequency converter with a voltage of 10 kV and a power of 2500 kW, a high-voltage frequency converter is installed in a block container and contains four cabinets: a multi-winding transformer cabinet, two multi-level voltage inverter cabinets and a braking resistor cabinet.

A multi-winding transformer 2 is installed in a multi-winding transformer cabinet and is a transformer of dry insulation class 10 / 0.69 kV. In contrast to the prototype, it has an assembled core with a single primary winding and 27 axially separate secondary windings (in the prototype 18 secondary windings). It is designed to convert voltage and protect motor 4 (three-phase AC motor with a voltage of 10 kV) from common mode voltage mode. The insulation material of transformer windings is classified at 220 ° C. To control the temperature of the phase and steel, the transformer has built-in temperature sensors with high voltage insulation. The temperature of the transformer is displayed on the monitor of the controller installed on the cabinet door of the multi-winding transformer, and is transmitted digitally to the control terminal of the electric drive. When the temperature reaches 100 ° C, a warning signal is generated, and at a temperature of 110 ° C, the inverter trips abnormally.

Unlike the prototype, which has liquid cooling, the developed converter of a high-voltage frequency-controlled electric drive with a voltage of 10 kV and a power of 2500 kW has air cooling. To ensure its cooling, tangential fans are used that are installed in the lower part of the multi-winding transformer cabinet. Three axial fans are installed on the doors of the multi-winding transformer cabinet, which provide air from the room to the inside.

A multi-level voltage inverter 3 is installed in two cabinets of a multi-level voltage inverter containing 27 power cells (in Fig. 1, A1-A9, B1-B9, C1-C9 are indicated). Each of the power cells of the multilevel voltage inverter of the converter is powered from the secondary windings of the multi-winding transformer of three-phase alternating voltage of 690 V and consists of a rectifier (semi-controlled), a filter (film capacitors) and a single-phase inverter on YuVT transistors (Fig. 2). The power cells of the multilevel voltage inverter are identical to each other and are installed on the design of the removable chassis for shutdown and local repair. The modular design of a single-phase inverter requires an average repair time of 30 minutes. Cells are interchangeable. At what to disconnect it is necessary to disconnect 5 connecting wires and 2 cables of fiber optics.

The performance of a high-voltage frequency-controlled electric drive is achieved through the use of the modular design of a multi-level voltage inverter 3. To obtain a voltage of 10 kV, low-voltage power single-phase inverters based on IGBT transistors (Fig. 2) - power cells of a multi-level voltage inverter are used in series. Power cells of a multilevel voltage inverter are controlled by the principle of pulse-width modulation. Each phase of the electric motor 4 is controlled by nine power cells of a multilevel voltage inverter 3, connected in series to form an output voltage of 10 kV. Groups of power cells are connected according to the "star" scheme, with floating neutral. Power is supplied to each cell through an isolated secondary winding of a multi-winding transformer 2. Each of the 27 secondary windings of a multi-winding transformer 2, the rated voltage of which is 690 V AC, provides 1/27 of the total power. The power cells of the multi-level voltage inverter 3 and the secondary windings of the multi-winding transformer 2 are isolated from each other. The actual voltage value can be adjusted from zero to the rated value. The power cell of the multi-level voltage inverter 3 is a complete functional unit with the implementation of protection against:

- short circuits;

- overheating of the IGBT module;

- increase the voltage in the DC link;

- lowering the voltage in the DC link;

- phase loss at the input of the cell of a multilevel voltage inverter.

All power cells of the multilevel voltage inverter 3 receive commands from the control terminal. These commands are sent to the power cells of the multilevel voltage inverter 3 through a fiber optic cable. The secondary windings of a multi-winding transformer 2, through which power is supplied to a multi-level voltage inverter 3 in each output phase, are used to obtain a phase angle between them. This neutralizes most harmonic currents generated by the individual power cells of the multilevel voltage inverter 3. Thus, the primary currents of the multi-winding transformer 2 become sinusoidal (Fig. 3).

The rectifier (Fig. 2), to which 690 V of alternating current is supplied from the secondary winding of the multi-winding transformer 2, charges the filters (film capacitors) of direct current to 1012 V of direct current. DC voltage is applied to a single-phase H-bridge of a single-phase inverter.

To implement the dynamic braking mode of a high-voltage variable frequency drive with a voltage of 10 kV and a power of 2500 kW, brake resistors are used that are installed in the cabinet of brake resistors.

The work of the proposed device.

The microprocessor control system for a high-voltage frequency-controlled electric drive with a voltage of 10 kV and a power of 2500 kW consists of functional blocks — blocks of current and voltage sensors (not shown in FIG.) And a control terminal (FIG. 4), consisting of:

- power supply unit - PSU;

- block optical input / output of communication with the inverter - BOVV SI;

- optical input / output unit for communication with sensors - BOVV SD;

- digital control unit - CBU;

- terminal block - BT;

- discrete input / output unit (quantity by unit in accordance with the order) - BDVV;

- control panel unit based on an industrial computer;

- cross-boards.

The microprocessor control system for a 10 kV high-voltage variable-voltage electric drive with a power of 2500 kW supports monitoring, configuration, diagnostics and control, regardless of the control method implemented, providing communication with the elements of a high-voltage variable-frequency electric drive.

The optical input / output unit for communication with sensors converts the digital data packets received from the sensors via the interface into optical ones. The processor module of the digital control unit performs the functions of motor control and generates commands for the optical input / output unit of communication with the inverter.

The control packets include a switching function for twenty-seven power cells of the multilevel voltage inverter 3 and additional control signals common to all cells of the multilevel voltage inverter 3. Moreover, the feedback packets to the digital control unit from the power cells of the multilevel voltage inverter 3 include general control the state of the cell of a multi-level voltage inverter 3, the health of individual IGBT transistors, the voltage value in the DC link of the multi-level power cell voltage inverter 3, control the completion of the charge of the filter (film capacitors) and the temperature of the crystals of IGBT transistors. In addition, the processor module of the digital control unit monitors the input voltages and currents to provide a function for measuring various values (for example, the coefficient of electric power, input power and harmonics), provides input protection (from overload, increased consumption of reactive currents, voltage control and phase failure) , and also controls the magnitude of the amplitude of the input and output voltage, the frequency and phase angle to implement the synchronous transition to the network.

The hardware interface between the control terminal (Fig. 4) and the boards of the power cells of a multilevel voltage inverter is implemented via a fiber-optic communication line. Data exchange with the power cell of a multilevel voltage inverter occurs through two optical channels.

The high-voltage variable-frequency drive uses vector control of asynchronous and synchronous motors. Using vector control provides an easy-to-use system that is comparable to the performance of a DC motor. The main components of vector control (Fig. 5) are as follows:

1. An adaptive observer that is used to determine flux linkage and engine speed.

2. Current controllers (RT), which are internal circuits.

3. Flow regulators (RP) and speed (RS), which are external circuits.

4. Cross-link compensators are used to compensate for cross-disturbances in the velocity loop and the magnetization loop in dynamic modes.

Controllability over the entire range of regulation of the rotational speed of the electric motor of the high-voltage frequency-controlled electric drive is provided by the control of the electromagnetic moment of the electric motor. The control of the electromagnetic moment is achieved due to the independent control of its components - flux linkage of the rotor and stator current (Fig. 5). Rotor Flux Link Control Channel built with a dual-circuit with an internal magnetization current control loop and with an external modulo flux linkage of the rotor of an equivalent two-phase generalized machine. The rotor angular velocity control channel contains control loops - internal, with respect to stator current and electromagnetic moment T _e and external, according to the angular velocity of the rotor.

The coordinate observer provides identification of the angular velocity of the rotor, the electromagnetic moment, the reference rotor flux vector, the current value of the rotation angle of the rotor flux vector, relative to the fixed coordinate system by the measured current and voltage values. The sum of the electric rotor speed and the rotor field frequency determines the frequency of the voltage across the stator ω _s = ω + ω _r . Integration of this quantity gives the current value of the angle ϑ _s , which is used in blocks and coordinate converters of the forward channel and the channel of the inverse transformation.

The formation of the output voltage of the Converter (PWM block in the diagram of Fig. 5) is carried out using sinusoidal pulse width modulation (PWM). The principle of generating the phase voltage of the converter is shown in FIG. 6. Use separate reference sawtooth signals for each level of the power cells of the phase converter. By shifting the carrier sawtooth signal to the corresponding voltage level of the DC link of the cell (block 1), and comparing it with the task for the phase voltage (block 2), we obtain a generalized switching function for one phase of the converter. When distributing the switching for individual power cells (block 3), the redundant state of the power cells of the multilevel voltage inverter 3 is taken into account. The algorithm allows to reduce the frequency of the switching function for an individual power cell of the multilevel voltage inverter by a multiple of their number in one phase of the high-voltage frequency converter.

The software of the high-voltage frequency converter guarantees continuous diagnostics of the control functions of the high-voltage variable-frequency drive with a voltage of 10 kV, 2500 kW and the display of all faults of a high-voltage variable-frequency drive with a voltage of 10 kV, 2500 kW at the control panel. The high-voltage frequency converter provides maximum motor protection and service safety thanks to a wide range of protections:

- from short circuits inside and at the output of the high-voltage frequency converter;

- time-current protection;

- overcurrent protection;

- from overheating of the multi-winding transformer 2 and power cells of the multi-level voltage inverter 3, including when the forced ventilation disappears;

- from overheating of the electric motor;

- from overvoltage of a high-voltage frequency converter;

- from the disappearance of the mains voltage, including phase failure;

- from unacceptable increase and decrease in voltage;

- protection in case of failure of the power cell of the multilevel voltage inverter 3 with its simultaneous shunting, lowering the output power and maintaining the regulation of the electric motor;

- from opening cabinet doors.

The panel personal computer that is part of the control terminal (not shown in FIG.) Functions as the operator panel of a high-voltage frequency converter, eliminates the need for potentiometers and tuning resistors and provides:

- monitoring the status of the main elements;

- formation of a log of events, alarms and operator actions;

- database maintenance;

- view and change the parameters of the electric motor;

- warning and alarm systems;

- the formation of historical trends in currents, linear voltages and electric motor speeds;

- start control and setting the speed of the drive motor;

- the ability to exchange information with other software tools installed on the same technical platform, or through communication channels.

VFD provides cascade control of electric motors with switching the electric motor to the mains or switching the electric mains to work from the frequency converter. In this case, the control system provides a synchronous transition without dynamic inrush currents to the supply network and electric motor and in the absence of inrush dynamic moment to the mechanism. Synchronous transition is carried out in accordance with the electromotive force of the electric motor and the supply network. Transient synchronization and pickup are presented in figure 7.

The application of the proposed device ensures the efficiency of a high-voltage variable-frequency drive through the use of a multi-level voltage inverter with an output voltage of 10 kV, to power an alternating current electric motor with a voltage of 10 kV and the use of a vector sensorless motor speed control system that provides the necessary accuracy of maintaining the ED speed, which increases the reliability of operation electric drive, as well as limiting the starting currents of electric motors at an acceptable level.

Claims (5)

1. The high-voltage frequency-controlled electric drive contains an actuator, an electric motor, a transformer and a high-voltage frequency converter, characterized in that the high-voltage frequency converter with a voltage of 10 kV and a power of 2500 kW includes a multi-winding transformer and a multi-level voltage inverter, and the high-voltage frequency converter is installed in the unit -container and contains four cabinets: a multi-winding transformer cabinet, two multi-level voltage inverter cabinets and a cabinet brake resistors. 2. The high-voltage frequency-controlled electric drive according to claim 1, characterized in that the multi-winding transformer is a transformer of dry insulation class 10 / 0.69 kV, containing an assembled core with a single primary winding and 27 axially-separated secondary windings, and has built-in temperature sensors with high voltage insulation. 3. A high-voltage frequency-controlled electric drive according to claim 1, characterized in that a controller is installed on the cabinet door of the multi-winding transformer with the ability to display the temperature of the transformer on the controller monitor. 4. A high-voltage frequency-controlled electric drive according to claim 1, characterized in that four tangential fans are installed in the lower part of the multi-winding transformer cabinet, and three axial fans with the possibility of air cooling are installed on the doors of the multi-winding transformer cabinet. 5. The high-voltage frequency-controlled electric drive according to claim 1, characterized in that the multi-level voltage inverter is installed in two cabinets of the multi-level voltage inverter, containing 27 power cells, each of the power cells of the multi-level voltage inverter of the converter is powered from the secondary windings of a three-phase AC voltage transformer 690 B and consists of a rectifier (semi-controlled), a filter (film capacitors) and a single-phase inverter on IGBT transistors with the possibility of creating 54- a multiple pulse rate of the AC rectification circuit and the formation of a smoothed sinusoidal form of current consumed from the network.