Excuse me, our power plant has a heating network, water pump motor jumping power frequency. What is the reason why the frequency conversion is normal?

Quoted from Inverter World, No.2, 2006

Application of Domestic High-voltage Inverter in Heating Network Pump of Wendeng Thermal Power Plant

Application of Domestic High Voltage Inverter in Heating Network Pump of Wendeng Thermal Power Plant

Shandong New Electronic Science and Technology Development Co., Ltd. Zhang Peibin

Zhang peibin

This paper mainly introduces the application of domestic high-voltage inverter in the water pump of #2 heating network in Wendeng Thermal Power Plant. The application results show that it has high economic and social benefits to use domestic high-voltage inverter to regulate speed and save energy for water pump equipment in power plant.

Keywords: high-pressure variable frequency water pump

This paper mainly introduces the application of domestic high-voltage inverter in # 2 heating network pump of Wendeng Thermal Power Plant. The application results show that it has high economic and social benefits to use domestic high-voltage inverter to transform the speed regulation and energy saving of water pump equipment in power plant.

Keywords: high-pressure variable frequency pump

1 Introduction

Wendeng Thermal Power Plant was built in 1996, with the installed capacity of 3× 170t/h high temperature and high pressure pulverized coal boiler and 2×35MW condensing steam turbine generator set, which is the first non-standard unit of the same type put into operation in China. Due to the strict management of thermal power plants and the stable operation of the units so far, Wendeng Thermal Power Plant has also become a base for visiting and studying thermal power plants in China.

In order to make full use of the circulating water of turbo-generator in Wendeng Thermal Power Plant to store energy, improve energy utilization rate and improve the investment environment in the east of Wendeng City, Wendeng City designed the first circulating water heating pipe network in 2003. The circulating water heating pipe network is built by Wendeng Electric Power Company, with a total length of 6 kilometers. The total investment of the first phase project is 23 million yuan, which can solve the heating area of Wendeng New Town of about 6,543,800 square meters. After the project is completed and put into production, according to the appraisal of relevant experts, it is considered that the safety and economic indicators of this pipe network operation have completely reached the leading level of similar pipe networks in China. During the operation of the thermal power plant, it is found that the water pump of #2 heating network runs frequently, and the steam enters the heating pipeline after passing through the condensing tower, and the pipeline pressure changes greatly. The pipeline is very unsafe and often bursts, so it is necessary to adjust the valve opening. A lot of electric energy is wasted on the valve.

After many investigations, the leaders of the thermal power plant believe that the following purposes can be achieved by controlling the water pump of the heating network with frequency converter: the closed-loop control of pipeline pressure with frequency converter can keep the pressure of the pipeline network constant and effectively prevent the occurrence of pipe explosion. At the same time, the energy wasted on the valve can be saved by changing the opening of the valve. Then the heating network pump is reformed by frequency conversion. The transformation results prove that the expected purpose has been achieved. Now, introduce the transformation situation.

2 Field equipment situation

After many investigations and cost-effective comparisons, the leaders of Wendeng Thermal Power Plant finally decided to choose the scenery brand JD-BP37 high-voltage inverter produced by Shandong Xinfengguang Electronic Technology Development Co., Ltd. to speed the pump unit of #2 heating network. In view of the 355KW/6KV high-voltage inverter project of the #2 heating network pump in Wendeng Thermal Power Plant, the two parties have made the transformation scheme of the #2 heating network pump high-voltage inverter through full understanding and analysis of the production process and field use conditions, and demonstration of the realizable scheme. The field equipment diagram is shown below. The main parameters of the motor and water pump of #2 heating network water pump unit are as follows:

1) water pump centrifugal fresh water pump

Model 14SH-9

The rated flow is1260m3/h h.

Rated elevator 75m

Rated shaft power 322KW

Rated efficiency 80%

Rated speed 1470 rpm

2) motor three-phase asynchronous motor

YKK400-4 model

Rated power 355KW

Rated voltage 6KV

The rated current is 42 .5 A..

Rated power factor 0.8

Rated speed 1480 rpm

Figure 1 Field Equipment Diagram

3 Feng Guang brand JD-BP37-400F high-voltage inverter

Wendeng Thermal Power Plant decided to adopt the scenery brand JD-BP37-400F high-voltage inverter control system produced by our company to speed the pump of #2 heating network. The following are some introductions of Feng Guang brand JD-BP37-400F high-voltage inverter.

3. 1JD-BP37-400F Main performance indicators of high-voltage inverter:

The rated power of the frequency converter is 400KW.

Rated output current 48A

The input frequency is 45Hz to 55Hz.

Rated input voltage 6KV

Allow voltage fluctuation of 20%

Input power factor ≥0.96 (at rated load)

The output voltage range is 0 ~ 6kV.

Frequency converter efficiency ≥96% (at rated load)

The output frequency range is 0 ~ 50hz.

Full-wave rectification of 36-pulse diode in rectification mode

Output mode: 6 unit sine wave pulse width modulation output per phase, direct 6KV output.

The frequency resolution is 0.0 1Hz.

Overload capacity 120% continuous 1 min 150%5S 200% immediate protection.

Control power supply 220VAC 10KVA.

Chinese color LCD touch screen operation keyboard

Interface language Simplified Chinese

Cooling mode forced air cooling

Protection grade IP20

Four analog inputs, 0 ~ 10V/4 ~ 20MA, can be set at will.

Two analog outputs, 0 ~ 10V/4 ~ 20mA optional.

On-off input and output 4-way input/16-way output (can be extended according to user's requirements)

Communication interface RS232 and RS485 interface.

Automatic recording and output of operation parameters, automatic fault recording, current limiting function, automatic adjustment of output voltage, unit bypass function, etc.

Special design can be made according to user's requirements.

3.2 frequency converter design requirements

Scenery brand JD-BP37-400F is an all-digital AC high-voltage frequency conversion control device produced by our company. Advanced power unit series carrier phase shifting technology and sine wave PWM modulation mode are adopted, and the Chinese interface is friendly. It has the characteristics of high reliability, superior performance and simple operation. The specific design requirements are as follows:

(1) High-voltage variable frequency speed regulation system adopts direct "high-high" conversion mode, and has a multilevel topology structure with units in series. The main structure consists of several groups of series and parallel power modules.

(2) The inverter control system adopts LED keyboard control and man-machine interface control, and the two modes are mutually standby. These two methods can increase or decrease the load and start and stop from the local interface. The fault record of the device shall be kept for at least one year. Provide free software upgrades. The man-machine interface is shown in Figure 2 below:

Figure 2 Man-machine interface diagram

(3) There are obvious charging, running and stopping instructions on the local inverter cabinet.

(4) The frequency converter provides two communication functions: standard RS485 and extended communication interface of touch screen processor.

(5) The frequency conversion device adopts voltage source type.

(6) The frequency conversion device shall be able to work normally at the following ambient temperatures: the maximum humidity shall not exceed 95%(20℃, the change rate of relative humidity shall not exceed 5% per hour, and no condensation will occur, and the working ambient temperature shall be 0℃ ~ 40℃, and the altitude shall be below1000m).

(7) In the speed range of 20 ~ 40%, the input power factor of the frequency conversion system reaches 0.95 without any power factor compensation.

(8) I/O of frequency conversion device can be parameterized according to user's requirements.

(9) The frequency conversion device does not require the length of the output cable, and the frequency conversion device ensures that the motor is not affected by * * * mode voltage and dv/dt stress.

(10) The power supply unit of frequency conversion device adopts modular design, which is convenient for extraction, movement and conversion from the rack, and all units are interchangeable. The inverter has the functions of internal unit bypass and external power frequency bypass, which ensures the normal operation of the whole system when the inverter fails, and provides the actual value of system derating after the module unit bypass.

The harmonic of (1 1) inverter output current is less than 2%, which meets the most stringent requirements of IEEE5 19 1992 and the national power supply department for voltage distortion, and is higher than the national standard GB 14549-93 for harmonic distortion.

(12) The current harmonics fed back by the inverter to the power grid are not more than 4%, which meets the most stringent requirements of IEEE5 19 1992 and the national power supply department for voltage distortion, and is higher than that of GB 14549-93 for harmonic distortion.

(13) The output waveform of the inverter will not cause motor resonance, and the torque ripple is less than 0. 1%.

(14) inverter has strong adaptability to the fluctuation of grid voltage, and can fully output when the grid voltage fluctuates from-10% to 10%, and can withstand the 30% drop of grid voltage and continue to run at reduced rate.

(15) The frequency conversion device can be operated remotely and switched between remote control and local control.

(16) The controlled motor can run normally in the whole frequency adjustment range. At the lowest output frequency, the rated current can be continuously output. At the highest output frequency, rated current or rated power can be output.

(17) The frequency conversion device has the following protections: over-current, over-current, under-voltage, open-phase protection, short-circuit protection, over-frequency protection, stall protection, inverter overload, motor overload, semiconductor device overheating protection, instantaneous power-off protection, etc. , and can trip the 6KV switch on the input side. The protection performance conforms to the provisions of relevant national standards.

(18) Inverter has data display of parameters such as AC output voltage, output current and output frequency.

(19) The frequency converter includes the following switching signals and analog signals:

Switch input: start, stop, manual/automatic switching and other signals.

Switch output: signals such as inverter high voltage ready, inverter running, inverter fault, inverter stop, etc.

Analog input: frequency adjustment (for example, given speed), etc.

Analog output: output frequency, output current, etc.

(20) The frequency conversion device has the function of fault self-diagnosis, providing Chinese instructions on the type and location of faults, displaying them locally and giving an alarm from a distance, which is convenient for operators and maintenance personnel to identify and solve problems. Frequency converter equipment monitors the ambient temperature. When the temperature exceeds the allowable ambient temperature of the frequency converter, the frequency converter will give an alarm.

(2 1) The system can run continuously in the environment of electronic noise, radio frequency interference and vibration, and the frequency conversion device meets the requirements of national standards for electromagnetic compatibility.

4 system transformation scheme

On September 15, 2005, Wendeng Thermal Power Plant and Shandong Xinfengguang Electronic Technology Development Co., Ltd. evaluated the procurement contract. June, 2005165438+1October, the high-voltage inverter was successfully debugged and passed the acceptance. The main circuit of the frequency conversion reconstruction scheme for the water pump of #2 heating network in Wendeng Thermal Power Plant is shown in Figure 3 below:

Fig. 3 Wiring diagram of main circuit of reconstruction scheme

K0 user original high voltage switch

K 1, K2 and K3 inverters bypass the high-voltage disconnectors of the switchgear.

BPQ JD-BP37-400F high voltage inverter

M high voltage motor

The frequency converter controls the heating network pump for one-to-one control, and the bypass switch cabinet is used for power supply/frequency conversion switching. K 1, K2 and K3 are three high-voltage isolating switches, which require that K2 and K3 cannot be closed at the same time to realize mechanical interlocking. K3 is turned off, K 1 and K2 are turned off, and the heating network pump operates with frequency conversion; K 1 is disconnected from K2, K3 is closed, and the heating network pump runs at the working frequency.

5 inverter operation

Judging from the application effect of frequency converter in operation, it has completely achieved the purpose of frequency conversion transformation of heating network pump by users, and its advantages are as follows:

(1) is easy to operate and observe.

All data and operation status of the inverter during operation can be displayed on the man-machine interface, such as operating frequency, input voltage, input current, output voltage, output current, open-closed loop, pressure value, etc. The man-machine interface is simple to operate and easy to observe.

(2) The frequency converter runs stably and has good performance.

Since Feng Guang brand JD-BP37-400F high-voltage inverter was put into operation, it has been running stably, the speed regulation is stable and reliable, the voltage and current are normal, and there is no abnormality.

(3) Reduce the labor intensity of the personnel on duty.

The personnel on duty operate through the microcomputer remote monitoring system, so it is no longer necessary to operate the valve frequently, and the workload is greatly reduced.

(4) Constant pressure control.

With constant pressure control, the user only needs to set the required pressure according to the actual pipe network needs, and the frequency converter automatically operates at constant pressure, so that the pressure setting is convenient, accurate and stable, which ensures the stable operation of the pipe network, avoids pipe explosion and improves the steam supply quality.

(5) The maintenance cost is reduced.

Because the inverter realizes the soft start of the motor, the starting current is small, and there is no mechanical impact on the heating network pump unit, which correspondingly prolongs the service life of the water pump, motor and valve, and greatly reduces the maintenance workload and cost.

(6) The power saving effect is obvious.

In order to compare the energy-saving situation of the heating network pump before and after the transformation, the data of one-week frequency conversion operation and one-week power frequency operation of the heating network pump are recorded in the following table 1 and table 2 respectively:

One-week frequency conversion operation data table 1

date

Motor current

(1)

Inverter input current (a)

Operating frequency of frequency converter (Hz)

Main water supply pressure (MPa)

Back to the jellyfish pipe pressure (MPa)

Return pipe flow of jellyfish (m 3 /h)

12.3

39. 1

20. 1

40.22

0.5 1

0.44

1002

12.4

39.2

20.2

40.43

0.5 1

0.44

1004

12.5

39.4

20.3

40.62

0.5 1

0.44

1005

12.6

39.0

20.0

40. 12

0.5 1

0.44

100 1

12.7

39.5

20.5

40.78

0.5 1

0.44

1007

12.8

39.4

20.4

40.62

0.5 1

0.44

1005

12.9

39.8

2 1.0

4 1.89

0.5 1

0.44

1009

Data table for one week of power frequency operation 2

date

Motor current

(1)

Main water supply pressure (MPa)

Back to the jellyfish pipe pressure (MPa)

Return pipe flow of jellyfish (m 3 /h)

12. 10

42. 1

0.68

0.58

1 120

12. 1 1

42. 1

0.68

0.57

1230

12. 12

42.2

0.68

0.58

1 100

12. 13

42.0

0.68

0.56

1 1 15

12. 14

42.5

0.68

0.58

1250

12. 15

42.4

0.68

0.58

12 10

12. 16

42.2

0.68

0.58

1 160

One cycle of frequency conversion operation: input voltage 6KV, average input current 20.3A, power factor 0.98, pump inlet pressure 0.44MPa, pump outlet pressure 0.5 1MPa, and average operating frequency 40.67Hz.

p = 1.732×6kv×20.3 a×0.98 = 206.7 kw。

One cycle of power frequency operation: voltage: 6KV, motor current: 42.2A, power factor: 0.8.

P work =1.732× 6kv× 42.2a× 0.8 = 350.8kw.

Power saving rate =( P-P transformer)/p×100% = (350.8kw-206.7kw)/350.8kw×100% = 41.1%.

The energy saving rate is as high as 4 1. 1%, and the energy saving effect is very remarkable.

Power saving in one day: (350.8KW-206.7KW) ×24h=3458.4KW? h

Calculated by running for 200 days a year, the electricity per kilowatt is 0.45 yuan/kilowatt? H calculation, the annual electricity saving is:

3458.4KW？ H×0.45×200 days =3 1 1256 yuan.

6 concluding remarks

The field operation of the inverter proves that JD-BP37-400F high-voltage inverter produced by Shandong Xinfengguang Electronic Technology Development Co., Ltd. has good performance and high reliability. After the transformation of frequency converter for #2 heating network pump in thermal power plant, the stability of the unit was improved, the pressure of the pipe network remained stable, and the energy saving effect was remarkable. The reliable and stable operation of the unit meets the heating demand of Wendeng City, improves the investment environment of Wendeng City, and is highly praised by all walks of life in Wendeng City. It is an ideal energy-saving project to realize frequency conversion speed regulation for high-power fans, pumps and other equipment in power plants, which has high economic and social benefits.

refer to

[1] Shandong new scenery electronic user manual [Z]. Shandong new scenery electronic technology development co., ltd.

[2] Shandong Xinfengguang Electronics JD-BP37-400F high-voltage variable frequency speed regulation system Wendeng Thermal Power Plant heating network pump debugging outline.

[3] Shandong Xinfengguang Electronics JD-BP37-400F High-voltage Variable Frequency Speed Regulation System Wendeng Thermal Power Plant Heating Network Pump Acceptance Report.

[4] Du, Guo Peibin, Han. Application of high-voltage inverter in cooling water circulating pump. Inverter World, 2005(7)

[5] Liu Haipeng, Guo Peibin, Sun Yabin. Application of high voltage inverter in feed water pump of Daye Special Steel Water Plant. Inverter World in 2005 (1 1)