YBP series high voltage frequency conversion speed regulating device

Series of high-voltage variable frequency speed regulating devices
Working principle and characteristics
The high-voltage variable frequency speed regulating system adopts the form of direct high-to-high conversion and is a unit series multi-level topology. The main structure is composed of multiple sets of power modules connected in series. As a result, the required high-voltage output is generated by the superposition of each group of low voltages. It has little harmonic pollution to the power grid, and the input harmonic distortion is less than 100%, which directly meets the harmonic suppression standards. The input power factor is high, and there is no need to use input harmonic filters and power factors. The output waveform quality of the compensation device is good, and the harmonic distortion of the output voltage is less than that. There are no problems such as additional heating of the motor and torque pulsation noise output/common mode voltage caused by harmonics. There is no need to add an output filter, and ordinary asynchronous motors can be used. Frequency conversion device output, each system has a power unit, each power unit is connected in series to form one phase, the system structure is as follows
Power unit
Each power unit is composed of a set of secondary sides of the input transformer In the power supply, the power units and the secondary windings of the transformer are insulated from each other. The secondary windings adopt a star-shaped edge connection method to achieve multiplexing to achieve the purpose of reducing the input harmonic current. The structure of each power unit is completely the same and can be interchanged. The circuit structure diagram is as follows. The system is a basic single-phase inverter circuit. The rectifier side is a diode three-phase full-bridge inverter bridge. The control mode is control, and there is an automatic unit. Bypass function. The highest voltage that the devices in the power unit bear is the voltage of the DC bus in the unit. Low-voltage power devices can be used directly. The devices do not need to be connected in series. There is no voltage balancing problem caused by devices in series. Moreover, the low-voltage power module used in the power unit has a simple drive circuit. , the technology is mature and reliable, the device works in a low-voltage state and is not prone to failure.
Unit bypass function: When a certain power module fails, it automatically operates by bypass. The frequency conversion device does not stop, but it needs to be derated. That is, a bypass circuit is connected in parallel between the output terminals of each power unit. When the power unit When a fault occurs, the trigger signal of the power unit is blocked, and then the bypass is turned on to ensure that the motor current can pass through and a path is still formed. This can maintain production requirements and greatly improve the reliability of system operation.
Overview
The power unit of the frequency converter is of modular design and can be pulled out, moved and replaced from the rack. All power units are completely identical. If a certain unit cannot be used due to failure, In normal operation, the device can be replaced with a spare unit at a time when the device is allowed to retire. That is, when the frequency converter is shut down and the high voltage is cut off, unplug the four optical fibers of the faulty unit and use a wrench to remove the five connections of the faulty unit. Remove the fixing screws between the faulty unit and the track. Gently remove the faulty unit and press the opposite button to remove it. Just install and connect the spare unit in sequence. Replacing a unit takes only minutes. No special tools are required to replace the unit.
The inverter side uses high switching frequency devices to ensure a good output waveform.
The isolation transformer on the input side protects the motor from common mode voltage.
The entire frequency conversion system adopts forced air cooling, the cooling system is reliable, the mean time between failures is the frequency conversion device itself, and each set of cooling devices is easy to disassemble and assemble, ensuring safe and reliable operation of the frequency conversion device.
Protection
The transformer incoming wiring terminal is large enough to facilitate connection with the incoming cable. The high-voltage lead conductors in the transformer cabinet can meet the allowable value of heat generation (<℃)
When the transformer is at each tap position, it can withstand the dynamic heat of a sudden short circuit at the line end without causing any damage, deformation or loosening of fasteners. .
Each power unit is protected by two-phase input fuses.
The frequency converter device also has the following protection functions
Overvoltage protection detects the DC bus voltage of each power module. If it exceeds the rated voltage, the frequency converter is protected.
Overcurrent protection: If the rated current of the motor is exceeded, it will be protected immediately.
Under-voltage protection detects the DC bus voltage of each power module. If it is lower than the set value, the inverter is protected. This protection actually includes protection against negative fluctuations in grid voltage.
Phase loss protection Phase loss protection is set on each power module. When the input side of the frequency converter loses phase or the fuse core of the power module melts, an alarm signal and protection will be issued.
Overload protection: The rated current of the motor is allowed for one minute per minute. If it exceeds the rated current, it will be protected. This protection actually includes protection against positive fluctuations in grid voltage.
Overheating protection includes double protection. Temperature detection is set up in the cabinet of the frequency conversion speed control system. When the ambient temperature exceeds the preset value, an alarm signal is sent. In addition, the main heating components, namely the rectifier transformer and power electronic power devices Temperature detection is placed on the controller. Once the limit temperature is exceeded (transformer ℃ ℃, power device ℃ will protect.
Optical fiber fault protection When the connecting fiber between the controller and the power module fails, an alarm signal will be issued and protection will occur.
For the above faults, the exact location of the fault is specified on the Chinese user interface to facilitate users to take corresponding measures.
External standard interface
The entire set of frequency conversion control devices, including all components such as phase-shifting transformers, frequency converter bypass cabinets and Integrated internal wiring design, the purchaser only needs to connect the high-voltage input, high-voltage output control power supply and control lines.
The specific definition of the external interface of the high-voltage inverter is as follows
) Switching values provided by the inverter
br/> The inverter adopts Siemens series, the standard digital configuration is point in and point out, and can be expanded/pointed and parameterized according to the different needs of users. Some of its output definitions
The inverter standby status indication indicates that the inverter is on standby and has the conditions to start.
The frequency converter running status indication indicates that the frequency converter is running.
When the inverter control status indication node is closed, it means that the inverter control right is on-site remote control. When the node is open, it means that the inverter control right is local inverter control.
The frequency converter minor fault indication indicates that the frequency converter generates an alarm signal. Contains information such as illegal opening of the cabinet door, over-temperature control power supply of the transformer, power outage, given signal disconnection, unit bypass (overheating, under-voltage, phase loss drive failure) etc. Cut off high voltage. Contains overvoltage, overcurrent, fiber optic fault, serious overheating of the transformer
Motor in power frequency bypass means that the motor is in power frequency bypass state.
) The frequency converter is provided to the high-voltage switch cabinet
High-voltage switch emergency breaking When the frequency converter has a serious fault, it will automatically break the high-voltage switch and the closing point will be effective.
All the above digital quantities use passive contact output, which is defined as valid when the contact is closed. Unless otherwise noted, the contact capacity is .
) Analog quantity provided by the frequency converter
The frequency converter can provide a current source output of 100 m, with a load capacity of 0. The corresponding relationship between the analog signal and the actual size of the physical quantity can be set by the user on the speed control device. The physical quantity corresponding to each analog output can be selected by the purchaser from the following parameters
Output frequency, given frequency, input current, output current input Voltage output voltage closed loop given value actual feedback value.
) Switch value provided to the inverter
) Start command dry contact, valid when the second pulse is closed, and the inverter starts running.
) Stop command dry contact, effective when the second pulse is closed, the inverter will stop normally.
) Emergency stop command dry contact, the closure remains valid, and the inverter stops in an emergency.
) The frequency converter analog quantity provided
The frequency converter adopts the Siemens series analog quantity expansion module to meet the above requirements. This module can provide the input of a current source or a voltage source, and its input can be adjusted according to the user's requirements. Different requirements are defined to meet the various needs of users. It can be defined as a given frequency, a given speed, pressure feedback, etc.
Note that the detailed interface design needs to be agreed upon by both parties during the signing of the technical agreement! The interface provided by this solution is for reference only.
Main circuit control
Manual bypass cabinet
Primary circuit diagram of manual bypass cabinet
In the bypass cabinet, there is a high-voltage isolation switch. In order to ensure that there is no reverse flow to the output end of the frequency converter, Power transmission, and the use of electromagnetic interlocking operating mechanism to achieve electromagnetic interlocking. When it is closed and disconnected, the motor runs at variable frequency. When it is disconnected and closed, the motor runs at power frequency. At this time, the frequency converter is isolated from the high voltage, which facilitates inspection, maintenance and debugging. When the bypass cabinet must be interlocked and closed with the superior high-voltage circuit breaker, it is absolutely not allowed to operate the bypass isolation switch and the frequency conversion output isolation switch to prevent arcing and ensure the safety of operators and equipment.
Fault opening connects the high-voltage breaking signal of the frequency converter and the frequency conversion input signal of the bypass cabinet in series, and then connects them in parallel to the high-voltage switch opening circuit. When the frequency converter is in the input state and a fault occurs in the frequency converter, when the high voltage input bypass of the frequency converter is disconnected and the frequency converter is in the input state, the fault opening of the frequency converter will be invalid.
The protection keeps the original protection of the motor and its setting value unchanged.
Mobile bypass cabinet
Automatic bypass cabinet
Frequency conversion/power frequency automatic switching
The bypass cabinet adds two isolation knife gates at the incoming and outgoing ends of the frequency converter to facilitate the When the inverter is withdrawn and the motor is running in bypass, troubleshooting or maintenance work on the inverter can be safely performed.
The bypass cabinet is mainly equipped with three vacuum contactors () and two knife isolation switches. It realizes electrical interlocking. When it is closed or disconnected, the motor runs at variable frequency. When it is disconnected or closed, the motor runs at power frequency.
In addition, when closed, the operating handle is locked and cannot be operated. When closed, the operating handle is locked and cannot be operated.
When the motor is running at power frequency, if you need to perform troubleshooting or maintenance on the frequency converter, remember to isolate and disconnect the knife gate in the open state.
Closing lockout connects the inverter closing permission signal in series to the closing circuit. When the inverter fails or is not ready, the vacuum contactor is not allowed to close in the closed state. If the inverter fails, the closing is allowed to open, trip, and disconnect the high-voltage input power of the inverter.
Bypass input connects the bypass input signal of the frequency converter to the closing circuit in parallel. In the variable frequency running state, if the frequency converter fails and automatic input is allowed, or the motor needs to be switched from variable frequency to industrial frequency (press the industrial frequency switching button
the system will first disconnect the high voltage input and output switch of the frequency converter And, after a certain delay, the bypass is turned on and closed, that is, the power frequency bypass switch is closed, and the motor is put into power frequency operation of the power grid.
The protection keeps the original protection of the motor and its setting value unchanged.
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