Shenzhen IPC Technology CO.,LTD Yangwei

Abstract:

This paper mainly describes the application of the IPC variable frequency energy feedback system which used in well winch. This system adopts PH7 series special inverter for hoisting industry and PFH series heavy-duty energy feedback equipment, and reconstruts the original rotor series resistance speed control mode, which can feed the regenerate energy of the hoisting motor back to the grid.

Key words:

special inverter of PH7 for hoisting industry PFH heavy-duty energy feedback equipment recontruction system of well winch
 

1. Introduction

Mine hoisting is an important link in the mining production process. The ore or coal mined from various working faces in the underground is transported by transportation equipment to the underground car yard through the underground roadway, and then lifted to the ground by the hoisting equipment. The lifting of personnel, the transportation of materials and equipment all need to be completed by lifting equipment. It is the hub that connects the underground production system of the mine and the surface industrial plaza. It is very appropriate to describe the important role of mine lifting with the image of "the throat of the mine". Mine hoist or mine winch, as the most widely used equipment in mine hoisting equipment, requires high reliability, safety, and economy. The frequency conversion feedback electronic control system of the lifting industry of CANON has been successfully used in the transformation of the winch of the Changce Silver Mine in Yizhang County of Chenzhou Yixin Industrial Co., Ltd. This article will introduce its application in detail.

2. Requirements for electric drive of mine winches

1. Load characteristics of mine winches

When a heavy object rises, the motor needs to overcome various resistances (including the gravity and friction of the heavy object), which is a resistance load.

When the weight is lowered, because the weight itself has the ability to drop according to the acceleration of gravity (potential energy), when the weight of the weight is greater than the friction resistance of the transmission mechanism, the weight of the weight (potential energy) is the driving force for the drop. The motor becomes the receiver of energy, so it belongs to the power load.

2. Requirements for the drive of the mine winch motor

①Large starting torque and good speed regulation characteristics;

②Strong overload capacity;

③It can output large torque at low frequency, and can't roll off when hanging;

④When lowering, the motor has a large amount of regenerative energy, and it is required to be able to process the motor's regenerative energy reasonably.

3. Disadvantages of traditional control system of mine winch

①High energy consumption

The traditional speed regulation method of mine winch is the speed regulation of winding motor rotor series resistance. This kind of control system consumes a large amount of slip power on the resistance of the rotor connected in series (in general, it can account for more than 30% of the total energy consumption), resulting in a large amount of waste of electric energy, which is undesirable in terms of energy saving and economy.

②Poor speed regulation performance

Rotor string resistance speed regulation is a stepped speed regulation, and the reduction of the speed is realized by the energy consumption of the external resistance of the rotor. The most important thing is that the lower the speed, the softer the mechanical characteristics of the motor, and the smaller the output torque. In addition, the step-by-step speed regulation has a great impact on the motor and mechanical equipment, the equipment is not running smoothly, the speed is not continuous, it is easy to fall off, and the failure rate is high. For the 24-hour continuous production mode of coal mines, the economic loss is large.

③ Poor system reliability

a. Frequent opening and closing of the contactor (the frequent opening and closing of the contactor under high current conditions) often results in the sintering of the contactor's contacts and the burning of the coil.

b The protection measures are not perfect, and the phenomenon of motor burning is prone to occur.

c. The brake is subject to relatively large impacts, and the brake shoes are severely worn, and the brake is prone to not tightly held, which often needs to be overhauled and replaced.

④High maintenance cost

a Contactors, wound motor rotor brushes, and slip rings often require maintenance and replacement, which is expensive.

b The reducer and brake are subject to heavy impact and often require maintenance.

c. The characteristics of the rotor string resistance speed regulation method itself ultimately lead to limited production efficiency (frequent failures and shutdowns and repairs), large maintenance workloads, and increased use and maintenance costs.

4. The advantages of the frequency conversion feedback electronic control system for mine winches

①The frequency converter has good speed regulation performance, large starting torque, hard mechanical characteristics and accurate positioning.

②The frequency converter runs smoothly, and has little impact on the reducer and brake, which reduces the maintenance of equipment and prolongs the service life of the hoist.

③After using the inverter, there is no need to use the contactor. At the same time, the winding motor can also be changed to a squirrel cage motor without maintenance of the brushes and slip rings.

④The frequency converter has high operating efficiency and has perfect protection, monitoring and self-diagnosis functions for the motor and system. If combined with PLC control, the reliability of the electric control system of the mine winch can be greatly improved.

⑤The energy feedback function can feed the regenerative energy of the motor back to the grid, which greatly saves electric energy.

3. Application of IPC frequency conversion feedback electric control system in energy-saving transformation of mine winch (380V)

1. Overview of on-site equipment

Belt brake mine hoisting winch
Project	Parameters	Remarks
Winch model	JT-1*0.8
Motor model	YR250S-6	1 station
Rated motor power	45kW
Motor rated voltage	380V
Motor stator rated current	88A
Rated motor frequency	50Hz
Rated motor speed	966r/min
Brake model	YWZ3-400/90
Motor control mode: winding motor rotor series resistance speed regulation

 

2. According to the load characteristics and control requirements of mine winch equipment, the main configuration of the frequency conversion feedback electric control system is as follows:

Project	Parameters	Remarks
System inverter	PH7-04-075NDC 75KW/165A/380V	1 station
System energy feedback device	PFH55-4 Rated current: 55A, peak current: 80A	1 station
System PLC	Siemens S7-200 CPU224/AC/DC/Relay 6ES7 214-1BD23-0XB8	1 station

 

3. Frequency conversion feedback and energy-saving transformation system for mine winches

After the mine winch system is reformed, the stepless speed regulation of the motor of the mine winch hoisting mechanism has greatly improved the control performance of the hoisting mechanism and reduced the huge impact on the motor and mechanical parts. At the same time, energy feedback will boost the regenerative energy of the motor back to the grid, which greatly saves electrical energy, reduces the ambient temperature of field equipment, and prolongs the service life of electrical equipment. The energy-saving retrofit system has two control cabinets, which are composed of inverters, energy feedback devices, PLCs, contactors, etc. The specific functions are summarized as follows:

1. After the system is reformed, the frequency conversion feedback control mode of the lifting motor and the original rotor series resistance power frequency control mode can be switched freely, and the two control modes are switched mutually and electrically interlocked to ensure the safety of the system.

2. After the system is reformed, the original operation mode and habits of the mine winch are retained, that is, the original cam controller gear control and operation mode are retained. In this way, the normal operation of the mine winch operator will not be affected, and the inspection of the special equipment of the mine winch is guaranteed.

3. The frequency conversion feedback electric control system of the hoisting mechanism has multiple protection functions such as short circuit, over voltage, over current, phase loss, overload, over temperature, etc., to maximize the protection of the hoisting mechanism of the mine winch.

4. The system uses a frequency converter to drive the motor of the lifting mechanism. When the motor drives the potential load and lowers it, the motor will be in the state of regenerative power generation. The energy feedback device will feed back the regenerative energy of the motor in the power generation state to the grid to ensure the normal operation of the frequency conversion system and greatly save electrical energy.

The schematic diagram of the system principle is as follows:

4. System debugging

① PLC program and control loop debugging. After the equipment is installed, the control circuit is powered on, but the main circuit is not powered on. Debug the control loop and PLC program to ensure the correct control of the control loop and PLC logic and the normal operation of all components.

② Debug the inverter.

a Disconnect the mine winch motor from the reducer, the inverter adopts V/F control mode to run without load, drag the motor to ensure that the motor runs stably and normally, and the inverter output voltage and current are normal.

b Disconnect the mine winch motor from the reducer, and the inverter adopts a PG-free vector control method to perform rotary self-learning to obtain motor parameters. Then use the no-load operation of the PG-free vector control mode, drag the motor, and adjust the corresponding parameters to ensure that the motor runs stably and the inverter output voltage and current are normal.

c Connect the winch motor to the reducer, the inverter adopts PG-free vector control mode, and runs the inverter with load to ensure the stable operation of the motor.

d Partial parameter settings of the inverter.

 

Serial number	Parameters	Name	Setting value	Content	Remarks
1	A1-02	Select the control mode	2	No PG vector control
2	b1-01	Select frequency command	1	Terminal
3	b1-02	Select run instruction	1	Terminal
4	b1-03	Select the stop method	0	Slow down and stop
5	C1-01	Acceleration time 1	10S
6	C1-02	Deceleration time 1	5S
7	C6-01	CT/VT selection	0	CT (low carrier constant torque use, 150% for 1 minute)
8	d1-02	Frequency command 2	10HZ
9	d1-03	Frequency command 3	23HZ
10	d1-04	Frequency instruction 4	28HZ
11	d1-05	Frequency command 5	33HZ
12	d1-06	Frequency instruction 6	38HZ
13	d1-07	Frequency Command 7	45HZ
14	E1-01	Set the input voltage	380V
15	E2-01	Motor rated current	88A
16	E2-02	Motor rated slip	2.75HZ
17	E2-03	Motor no-load current	31.3A
18	E2-04	Number of motor poles	6
19	E2-05	Motor wire resistance	0.178Ω
20	E2-06	Motor leakage resistance	21.0%
21	E2-07	Motor core saturation factor 1	0.37
22	E2-08	Motor core saturation factor 2	0.63
23	E2-11	Rated motor capacity	45KW
24	H1-01	Select the function of terminal S3	3	Multi-speed 1
25	H1-02	Select the function of terminal S4	4	Multi-speed 2
26	H1-03	Select the function of terminal S5	5	Multi-speed 3
27	H1-04	Select the function of terminal S6	14	Fault reset
28	T1-01	Select self-learning mode	0	Rotating self-learning
29	T1-02	Motor output power	45KW
30	T1-03	Motor rated voltage	380V
31	T1-04	Motor rated current	88A
32	T1-05	Motor fundamental frequency	50HZ
33	T1-06	Number of motor poles	6
34	T1-07	Rated motor speed	966r/min

 

③ Debugging of energy feedback device.

Carry out the no-load and heavy-load drop tests of the mine winch, correctly set the feedback action voltage value of the energy feedback device, and ensure the normal operation of the frequency converter and the energy feedback system.

④ Debug and run the system as a whole.

The entire system is tested as a whole to ensure that the mine winch is hoisted and lowered without load, and heavy-loaded. The speed of each gear meets the requirements, the gear shift is normal, and the frequency converter and energy feedback device are operating normally. And carry out the work and frequency conversion switching test to ensure the normal switching and the normal operation of the power frequency.

Live picture

4, the application effect and customer evaluation of the IPC frequency conversion feedback electric control system in the energy-saving transformation of the mine winch

he actual operation of the system proves that the application of the IPC frequency conversion feedback electronic control system in the energy-saving transformation of the mine winch does not change the operation mode of the original mine winch, and the original handbrake can basically no longer be used, which simplifies the operation. The system runs stably and reliably, with excellent speed regulation performance, large starting torque and low-frequency torque output; when the lifting mechanism is lowered, the excess electric energy under the regenerative power generation state of the motor is fed back to the grid, which greatly saves electric energy. The customer is very satisfied with the use effect of the IPC frequency conversion feedback electric control system in the energy-saving transformation of the mine winch. After actual measurement, the IPC frequency conversion feedback electronic control system can save more than 28% of electric energy compared with the original mine winch winding motor rotor series resistance speed regulation method.

5, concluding remarks

The application of the IPC frequency conversion feedback electronic control system in the energy-saving transformation of mine winches has improved the automation level of lifting winch equipment in the mining industry, and has accelerated the upgrading of industrial equipment in the mining industry. It has played a very positive role in increasing the production capacity of the mining industry and ensuring the safety of production in the mining industry.

More importantly, the mine hoisting winch equipment is a large-scale mine equipment, and its energy consumption accounts for a large proportion of the total energy consumption of the entire mine production. Compared with the winding motor rotor series resistance speed control system, the frequency conversion feedback electronic control system can greatly save Electricity can really reduce the cost of production in the mining industry and generate economic benefits.

6. References

1. "User Manual of PH7 Crane Inverter" Shenzhen Hexing Canon Technology Co., Ltd.

2. "PFH Heavy-Duty Feedback Device User Manual" Shenzhen Hexing Canon Technology Co., Ltd.

3. "Mining Machinery and Equipment" China University of Mining and Technology Press Xie Xichun and Li Xiaohuo Editor-in-Chief

4. "Mining Engineering and Equipment Technology" Metallurgical Industry Press Wang Rongxiang and Ren Xiaoqian Editor-in-Chief

 

Energy feedback technology scheme of winch for Tengqing Coal Industry in Liupanshui City (660V)

Chapter One Application Cases of Mine Winch Energy Feedback

1. Equipment overview

The main parameters of the mine winch are as follows:

 

Well winch
Serial number	Project	Parameters/Specifications	Remarks
1	Rated motor power	450kW	1 station
2	Motor rated voltage	660VAC
3	Inverter power	Schneider 630KW/660vac
4	Mine shaft length	630 meters
5	Mine inclination	45 degrees
6	Winch speed	3m/s
Note:

 

2. Treatment of regenerative energy

When a frequency converter is used to drive the motor of the lifting mechanism, and the motor is dragged to lower the potential load, the actual speed of the motor will quickly exceed its synchronous speed, so that the motor will be in the state of regenerative power generation. The six feedback diodes in the inverter convert the mechanical energy of the transmission mechanism into electrical energy and feed it back to the intermediate DC loop, and cause the voltage across the energy storage capacitor to rise. If necessary measures are not taken, the inverter will trip over voltage when the DC link capacitor voltage rises to the protection limit value.

In high-performance engineering frequency converters, there are the following two schemes for continuous regeneration energy processing. ① Set a resistor in the intermediate DC circuit to allow the continuous regenerative energy to be consumed in the form of heat through the resistor. This method is called energy consumption braking; ② The regenerative rectifier method is used to send the continuous regenerative energy back to the grid. This method It is called feedback braking. The two braking methods are described in detail below.

(1) Energy-consuming braking

Energy-consuming braking is composed of a braking unit and a braking resistor. After the inverter is equipped with a braking unit and a braking resistor, its energy consumption braking capacity depends on the allowable power of the braking resistor. Therefore, when calculating the regenerative power PM, PM must be satisfied

① Calculate regenerative energy EM

② Calculate the regenerative power PM

PM = EM/t0

Where PM——the effective regenerative power generated by the motor during braking, W

EM——The regenerative energy when the mechanism decelerates rapidly and descends, J

t0——brake cycle time, S

③ Choose a suitable combination of braking unit/brake resistance To select a suitable combination of braking unit/brake resistance, the following conditions must be met:

PM

Where PM——the effective regenerative power generated by the motor during braking, W

PR——allowable power of braking resistor, W

PDB——allowable power of brake unit, W

When the calculated PM>PR, it indicates that the processing capacity of the braking resistor is exceeded, and the load inertia and deceleration time need to be recalculated.

④ Calculation of braking resistor RB0

In regenerative braking, even if the braking resistor is not set, about 20% of the braking torque can be obtained by the internal loss of the motor, so the required resistance value RB0 can be calculated by the following formula: VC²

RB0 = —————————— 1.027 (TB-0.2TM) n1

Where VC——The voltage of the DC circuit in the inverter (about 960V), V

TB——brake torque, kg·m

TM——Motor rated torque, kg·m

n1——The speed when the motor starts to decelerate, rpm

The discharge circuit of energy-consuming braking consists of a braking unit and a braking resistor. The maximum current is limited by the maximum allowable current IC of the braking transistor. The minimum allowable value of the braking resistor is RMIN=VC/IC. Therefore, when the braking resistor is selected, its actual value RB should meet the following conditions:

RMIN <RB <RB0

The above selection is based on accurate calculations. If accurate calculation data cannot be obtained in actual engineering, the selection can also be made according to the empirical formula given below.

① Regenerative power PM of the lifting mechanism

PM = Pb×ηtotal

ηtotal=ηmec×ηmot×0.98

In the above formula, Pb is the actual load regenerative power, ηmec is the mechanical efficiency, and ηmot is the motor efficiency.

②Approximate calculation of braking resistor RB0 VC² RB0 = —— PM

(2) Feedback braking

In order to realize the feedback of the regenerative power generated by the motor in the braking state to the grid, the grid-side converter should adopt an invertible converter. The IPC-PFH series of heavy-duty energy feedback devices launched by Shenzhen Hexing Canada Energy Technology Co., Ltd. have the same grid-side converter and inverter structure, and use a grid voltage identification board with PWM control. Due to the use of PWM control technology, the magnitude and phase of the AC voltage on the grid side can be controlled, and the AC input current can be in phase with the grid and close to a sine wave. The power factor of the system is greater than 0.96, and 97% of the grid feedback is achieved during feedback braking. ability.

The IPC-PFH series energy feedback device can feed back the regenerative electric energy generated in the process of motor speed adjustment to the grid, avoiding the energy loss caused by the resistance heating of the conventional energy-consuming braking unit, so as to achieve the ideal energy-saving effect. Achieve efficient operation.

3. Selection and configuration

According to the working conditions and parameters of the site, combined with our company's experience in engineering transformation of mine winch equipment, it is recommended that the energy feedback device be selected as follows:

 

PC-PFH series heavy-duty energy feedback device
Project	Parameters	Remarks
Model	PFH-06-250-NDC
Rated voltage	660VAC
Rated current	140A
Peak current	220A
Quantity	2 sets	2 units are used in parallel

 

4. Control principle

The main circuit schematic diagram of the mine winch hoisting mechanism with energy feedback device is shown in the figure:

The input of the electric energy feedback device is connected to the DC bus of the frequency converter, and the output of the electric energy feedback device is directly connected to the grid. The PFH series energy feedback device has been equipped with reactors and noise filters as standard, which will not cause interference to the power grid and surrounding electrical equipment.

After installing the PFH series of heavy-duty energy feedback devices, the energy saving rate is expected to be between 20%-50%.

5. Operation process of installation and use of energy feedback device

n install

(1) Before installation, you must read the user manual carefully, and refer to the connection diagram of the feedback device cabinet and the control cabinet of the mine winch inverter when connecting.

(2) Completely disconnect the main power supply of the lifting mechanism.

(3) When wiring, pay attention to the positive (+) and negative (-) polarity of the DC input terminal of the feedback unit, and it is strictly forbidden to connect the polarity in reverse.

(4) Note that the AC output terminal (AC-A, AC-B, AC-C) of the feedback unit is connected to the grid side without polarity requirements, and it is strictly prohibited to connect to the motor side.

n Power transmission

(1) If a circuit breaker is installed at the output end of the feedback device cabinet, close the circuit breaker first.

(2) The total power supply of the lifting mechanism is transmitted, and the panel of the feedback device cabinet is displayed in 5 to 10 seconds.

n Power off

(1) The main power supply of the lifting mechanism is cut off.

(2) The output switch of the feedback device cabinet is off.

n Matters needing attention

(1) It is strictly forbidden to continuously supply power to the main power switch of the hoisting mechanism of the mine winch without disconnecting the feedback device cabinet. When the power is transmitted, the internal voltage of the inverter must be completely discharged before the power is transmitted again, so as to avoid the fuse inside the feedback device. damage.

(2) It is strictly forbidden to directly open the circuit breaker at the output end of the feedback device cabinet when the power is on.

Chapter 2 IPC-PFH series (660V) heavy-duty energy feedback device product introduction

IPC-PFH series heavy-duty energy feedback device is a high-performance transmission energy-saving product manufactured using Canadian technology. It has been widely used in ports, elevators, cranes, mine hoists, belt conveyors, centrifuges, oilfield pumping units, Wind power grid-connected power generation and other occasions.

The IPC-PFH series of heavy-duty energy feedback devices can feed back the regenerative energy generated in the process of motor speed adjustment to the grid, avoiding the energy loss caused by the resistance heating of the conventional energy-consuming braking unit, so as to achieve considerable Energy-saving effects can also achieve grid-connected power generation such as wind and solar energy. Reactors and noise filters have been installed inside this series of products, which can be directly connected to the power grid without causing interference to the power grid and surrounding electrical equipment.

The principle diagram of the main circuit is shown in the figure below:

When the mine winch adopts a frequency converter-driven hoisting mechanism to drag the potential load down or the running mechanism decelerates rapidly and runs downwind, the asynchronous motor will be in the state of regenerative power generation. The inverter part of the frequency converter converts the mechanical energy of the transmission mechanism into electrical energy and feeds it back to the intermediate DC circuit of the frequency converter, and causes the voltage across the energy storage capacitor to rise. Under normal circumstances, in order to ensure the normal operation of the inverter system, energy consumption resistors are used to consume this part of the regenerative electric energy. However, due to the overheating of the resistor, it will cause the resistor and its lead to be burned, which will cause a series of safety problems, and more importantly, a great waste of regenerative electric energy.

After the application of the PHF series heavy-duty feedback device, the inverter has a four-quadrant operation function. The regenerative electric energy generated by the motor is returned to the network in the form of a sine wave through a series of transformations, thus ensuring the normal operation of the system and reaching a low level. The purpose of electricity.

The unique "full voltage automatic tracking" and "zero current" processing technology of the PFH series heavy-duty feedback device improves the current quality when the feedback current crosses zero, and improves the stability and power factor of the heavy-duty feedback. The PFH heavy-duty feedback device has a built-in fuse, which will not damage the original control system even if the output is short-circuited.

Technical specifications of IPC-PHF series heavy-duty energy feedback device: