Application of Zinvert Series High-voltage Variable Frequency Speed ​​Regulating System in Double-inducing Fan of 600MW Unit

Abstract : This paper analyzes the process and reliability requirements of 600 MW thermal power unit double-induced fan, and introduces the technical scheme and energy-saving of the frequency conversion reform of the double-induced fan of #1 furnace of Zinvert series high-voltage frequency conversion debugging system in Hunan Datang Huayin Jinzhushan Thermal Power Generation Branch. The application of the effect provides a certain experience for the application of the high voltage variable frequency speed control system to the double induced draft fan of the 600 MW thermal power generating unit.

Keywords: high-voltage variable frequency speed control system 600MW unit double-induced fan energy-saving

1. Project Overview

Datang Huayin Jinzhushan Thermal Power Generation Branch Company is located in Lengshuijiang City and is affiliated to Huayin Electric Power Co., Ltd. The existing #1 unit, #2 unit, and #3 unit are put into operation. The total installed capacity is 1800 MW, and the No. 4 plant expansion site is reserved. . The company's #1 and #2 furnaces use two DG2030/17.6-II3 boilers produced by Dongfang Boiler Co., Ltd. Its main technical features are subcritical parameters, natural circulation, double-arch furnace, intermediate reheat and double tail smoke. Road, balanced ventilation, open-air layout, full steel structure, full suspension structure, solid slag discharge, "W" flame boiler, can burn inferior anthracite coal. The boilers are symmetrically equipped with 2 sets of movable blades, 2 sets of adjustable primary blades and 2 sets of adjustable axial flow induced draft fans.

When the generator set is in normal operation, the furnace pressure of the boiler is adjusted by the lead and blower in the wind-smoke system. The adjustment method in the case of power frequency is: After the fan is started normally, the leading stator of the induced draft fan is adjusted according to the load of the boiler. The opening degree is to maintain the negative pressure in the hearth. When the unit load reaches 400MW or more, adjust the current of the induced draft fans A and B to make the deviation within 10A, and then set the leading static blade of the induced draft fan to be automatic. According to the target pressure set by the furnace, after the PID calculation, DCS will automatically adjust the pilot stator vane opening of the induced draft fan.

2,600MW unit induced draft fan frequency conversion transformation

At present, the induced draft fans of the 3 600MW furnaces of Datang Huayin Jinzhushan Thermal Power Generation Branch Co., Ltd. are all started with a direct series frequency and no soft-start devices. Because of the national energy saving and consumption regulation and the actual regulation requirements of induced draft fan, after leading experts of Datang Huayin Electric Power Co., Ltd. conducted a technical inspection of high-voltage variable frequency speed control system in China, Zinvert-A8H4150/06Y high-voltage inverter of Guangzhou Zhiguang Electric Co., Ltd. was finally adopted. Speed ​​control device, to reform the two induced draft fans of #1 furnace.

2.1 #1 Furnace Fan Fan Motor and Fan Parameters

Table 1 motor and fan parameter configuration table

2.2 Parameter Configuration of High-voltage Variable Frequency Speed ​​Regulating System

Table 2 High-voltage variable frequency speed control system parameter configuration table

2.3 High-voltage variable frequency speed control system transformation plan

The two induced draft fans of #1 furnace are equipped with two high pressure variable frequency speed control systems, one for each, and control and control the induced draft fans A and B, respectively. The air volume of the induced draft fan is adjusted by high-voltage frequency conversion to meet the production needs. After the transformation of the high voltage variable frequency speed control system, the following figure is as follows:

Fig. 1 Primary wiring diagram of high voltage variable frequency speed control system

In the frequency conversion mode, the K1 is closed, the K2 is switched to the inverter position, the power frequency status, the K1 is separated, and the K2 is switched to the power frequency position. Among them, the knife gate K1 and the knife gate K2 are manual isolation barriers inside the inverter, and J is the vacuum contactor inside the inverter. K1, K2 can only be manually operated without high pressure, inverter stop status and contactor J disconnected. The vacuum contactor J is automatically closed 1 second after the inverter sends the high voltage, and after the inverter stops and 5 seconds after breaking the high voltage, the contactor J is automatically separated.

Fig. 2 Field operation diagram of high-voltage variable-frequency speed control system Fig. 3 Fan diagram of high-voltage variable-frequency speed control system control

2.4 DCS logic and control method of high voltage variable frequency speed control system

2.4.1 DCS logic of high voltage variable frequency speed control system

1) Operating status signal of induced draft fan: frequency conversion status, using high-voltage frequency conversion running status signal, knife switch K1, frequency conversion status node signal phase of knife switch K2 and the signal after as the operation signal of induced draft fan; power frequency status, using 6KV The auxiliary signal of the closing auxiliary contact of the high-voltage switchgear and the power frequency status node signal of the high-voltage variable-frequency switch K2 is used as the running signal of the induced draft fan. In the frequency conversion state, if the operating state signal of the high-voltage frequency conversion is lost and there is no recovery after the delay of 4S, the operation signal of the induced draft fan is lost. After the loss of operation signal of the induced draft fan, the system is protected by RB.

2) The tripping status signal of the induced draft fan: The tripping signal of the high-voltage frequency conversion is operated by a relay to control two identical nodes to issue a trip signal, and one of the trip signals is directly connected to the tripping loop of the 6KV high-voltage switch cabinet to play the role of protection tripping. Another trip signal is received in the background DCS for logic and status display.

The high voltage frequency change sends the DCS trip pulse signal and the K2 frequency conversion node signal of the knife gate and the subsequent signal triggers the logic trigger to send a high level signal as a standby 6KV high voltage switch trip signal. When the high-voltage frequency conversion is restarted, the high-voltage frequency conversion operating state signal, the auxiliary auxiliary contact signal of the 6KV high-voltage switch cabinet and the frequency conversion state node signal of the knife gate K2 are used to reset the level signal of the trigger.

2.4.2 DCS control method of high voltage variable frequency speed control system

High-voltage variable frequency remote start, stop, emergency stop, and reset operations, the status of various quantities and frequency given, feedback, etc. are sent to the DCS terminal and done on the operation screen, you can manually start and stop the high voltage inverter on the DCS screen, Frequency can be manually input or automatic PID adjustment in two ways. The method of automatic PID given frequency is as follows: First, start the high-voltage frequency conversion, manually adjust the stator blade of the induced draft fan to about 30%, and set the frequency of the two inverters at the same time and manually set the frequency to be 30Hz for high-voltage frequency conversion, and then fine-tune the frequency so that A and B are cited. The current balance of the fan (current difference within 10A, if the current deviation is too large, it will cause the draft fan to grab the wind, stall), the two high-voltage frequency conversion automatic (system PID adjustment), with the increase of boiler load, start adjusting A , B draught fan leading stator vane opening until the static vane opening is adjusted to more than 90%. After the input is automatic, the target pressure and frequency deviation of the high-voltage frequency conversion can be set to achieve accurate control of the PID.

3, transformation effect analysis

Due to #1 furnace design, its draft fan motor and fan selection is too large, so when matching high-voltage variable frequency speed control system, according to # 1 furnace induced draft fan long-term operating conditions current matching. At the same time, because the boiler does not require high quality coal, as long as the coal's standard heat reaches 3,000 to 5,500 calories can be burned, resulting in different coal quality on the induced draft fan air flow requirements are not the same, in the low coal combustion, the induced draft fan The current is relatively large, when the high-coal combustion, the current of the induced draft fan is small, so the induced draft fan of # 1 furnace puts high requirements on the current variation and the stability of the operation of the high-voltage variable frequency speed control system. The Zinvert series of high-voltage variable frequency speed control system of Guangzhou Zhiguang Electric Co., Ltd. owns patented technology SCP anti-short circuit technology and core STT technology, which makes the equipment anti-interference force and voltage and current disturbance adaptability is very strong, as well as a sound input side The comprehensive protection of the voltage, current, and output motor motors provides a powerful guarantee for the stable operation of the induced draft fan.

According to the internal scheduling of the power plant, the operating load of the #1 furnace is always fluctuating. Generally, the load is between 450 MW and 500 MW in the daytime, and between 500 MW and 550 MW in the evening, and less time is spent at full load. During the period from November 11 to November 20, 2009, the operating frequency of the high-voltage variable-frequency variable-speed system and the energy-saving test data were recorded. The data under different loads is shown in the following table:

Table 3 High-voltage variable frequency speed control system parameter configuration table

Table 4 High-voltage variable frequency speed control system parameter configuration table

According to Data used by Datang Huayin Jinzhushan Power Plant, the voltage is 6.3KV and the power factor of the power frequency is 0.85, so the energy saving before and after the transformation of the above two loads can be calculated:

When the load is 508.5MW, the power consumption of the induced draft fan under power frequency operation is:

A: 6.3 × 209.766 × 0.85 × 1.732 = 1945.55 KW;

B: 6.3×205.664×0.85×1.732=1907.5 KW;

The power consumption of the induced draft fan under the operating condition of the high-voltage frequency conversion debugging system is:

A: 6.3×111.3×0.982×1.732=1192.6;

B: 6.3×109.6×0.982×1.732=1174.38KW;

According to the actual situation of the power plant, the #1 furnace induced draft fan is calculated according to the annual operation of 4000 hours, according to the power plant's on-grid electricity price of 0.4212 yuan/degree, and its annual electricity saving rate is:

A: (1945.55-1192.6) × 0.4212 × 4000 = 126.8570 million;

B: (1907.5-1174.38)×0.4212×4000=123.5160 million;

When the load is 508.5MW, the power consumption of the induced draft fan under power frequency operation is:

A: 6.3×248.438×0.85×1.732=2304.23 KW;

B: 6.3×245.133×0.85×1.732=2273.57 KW;

The power consumption of the induced draft fan under the operating condition of the high-voltage frequency conversion debugging system is:

A: 6.3×155.9×0.982×1.732=1670.5 KW;

B: 6.3×157.6×0.982×1.732=1688.71KW;

According to the actual situation of the power plant, the #1 furnace induced draft fan is calculated according to the annual operation of 4000 hours, according to the on-grid power price of the power plant is 0.4 yuan/degree, and the annual electricity saving rate is:

A: (2304.23-1670.5) × 0.4212 × 4000 = 106.7708 million yuan;

B:(2273.57-1688.71)×0.4212×4000=98.5372 million;

According to the above data, it can be seen that the energy saving effect of #1 furnace only allowing 167 days of frequency conversion in one year is very obvious. If the annual power generation time is increased to 200 days, the electricity cost for a single inverter will increase by 200,000 yuan. Yuan around. At the same time, the lower the load of #1 furnace operation, the better the energy-saving effect of high-voltage frequency conversion. The use of high-voltage variable frequency speed control system in addition to a very good energy-saving effect, but also brought the following benefits:

1) Eliminating the large current fluctuations of the induced draft fan caused by the difference in the combustion of coal, making the input current of the induced draft fan increase steadily and without sudden changes in the range;

2) The power factor at the network side is increased, the power factor is increased from the power frequency of 0.85 to 0.982, and the stability of the power factor is also improved;

3) After adopting high-voltage variable-frequency speed control system, the soft start of the motor is realized, and the starting current is below 450A, avoiding the impact of more than 1000 ampere-currents on the motor when the motor power frequency is started, and also avoiding the impact on the power grid, and the use of the motor. Life expectancy has also increased;

4, summary

After the transformation of the A and B induced draft fans of Datang Huayin Jinzhushan Power Generation Company's No. 1 furnace, the high-voltage frequency conversion operation is very good, the control and adjustment are convenient, and the production needs of different loads, in addition to its significant energy-saving effect, reduce the plant Electricity consumption, cost savings, and increased market competitiveness.

references:

[1] Jinzhushan Power Plant internal network #1 furnace statistics, Hunan, Datang Huayin Jinzhushan Thermal Power Generation Branch;

[2] ZINVERT series of high-voltage Frequency control system training materials, Guangzhou, Guangzhou Zhiguang Motor Co., Ltd.