Abstract: This paper introduces the application of ABB acs-510 frequency converter in heat, and provides a method of using MODBUS to control the use of frequency converter
key words: square load of frequency converter
thermal heating mode has the characteristics of good heating effect and no pollution. As the main part of heat, the automatic control level of thermal station directly affects the heating situation of users. The energy conservation of thermal station is also the main part of thermal energy conservation, so the energy conservation and safe operation of thermal station are of great significance
2 project overview
there are 120 heating stations in the central heating project of Harbin Airport Development Zone, with a heating area of about 5.7 million mm2 and a total load of 10000j/h. The primary water supply temperature is designed to be 130 ℃ ~70 ℃. The heating mode is hot water heating. The function of the heating station is mainly to provide heat for residents and factories. The heating station should provide primary and secondary heat exchange and secondary pressurization. The secondary pressurization and circulating pump are controlled by frequency converter, ABB ACS510 series frequency converter is used as the transmission part of circulating pump and make-up pump in the thermal power station of the project to improve the automatic control level of the thermal power station and realize energy conservation
3 process introduction
composition of thermal power station [1: it mainly consists of heat exchanger, automatic control panel, circulating pump, make-up pump and communication special line, as shown in the attached figure.
attached figure automatic control of thermal power station and thermal process diagram
automatic control part [2 it is mainly composed of a Schneider PLC, which collects various parameters and states on the site into the PLC, and the PLC transmits the collected data to the dispatching center through ADSL. The dispatching center transmits the indoor temperature signal returned by the user back to the PLC of the heating station by the dispatching center. The automatic operation of the heating station is realized by controlling the secondary water supply temperature and water supply flow according to the indoor temperature of the end user. Is the indoor temperature of the user The standard is based on the temperature curve and outdoor temperature released by the urban heating office
4 function of the thermal power station
after exchanging the primary heat through the heat exchanger, the secondary hot water is sent to each user. The operation of the thermal power station is mainly based on whether the indoor temperature of the end user of the station reaches the heating standard of the city, the operation cost of the thermal power station, and the degree of energy conservation, Based on the above situation, the heating method of the thermal power station adopts the combination of quality and quantity adjustment and consumption upgrading to achieve heating standards and energy conservation. Quality regulation (1) is to control the secondary water supply temperature by adjusting the primary water supply flow regulating valve. The quality control method is simple, but the degree of energy conservation is poor. Quantity adjustment (I don't smell the pungent odor in the traditional plastic processing process 1) is to add frequency conversion control to the circulating pump (3). By adjusting the secondary water supply flow to ensure that the end user's room temperature meets the standard, this method has a very good energy saving effect. Our control mode is an optimized control mode with quantity regulation as the main and quality regulation as the auxiliary. This control mode can save 30% of electric energy every year, and improve the imbalance through circulating pump frequency conversion and make-up pump frequency conversion (3) 20% - 30% of water can be saved every year. To ensure that the indoor temperature of thermal end users meets the standard and save electric energy to the greatest extent, the economic benefits are very considerable
5 circulating pump control mode
the circulating pump adopts ABB acs-510 frequency converter, which is an application of square load. Acs-510 has low cost and its own Modbus communication function. We use MODBUS bus to control the frequency converter, including the start, stop, speed AI setting, etc. the operating parameters of the frequency converter are transmitted to PLC through modbus, and then transmitted back to the dispatching center by PLC. This mode is convenient for the assembly of the control cabinet, Because of less wiring, less auxiliary components and low failure rate, this kind of bus control speed can reach the given value of aisubstation of district heat supply network, which has high accuracy and good effectiveness
two 37KW circulating pumps are set in the station, one for operation and one for standby. The frequency converter adopts one driving two
(1) frequency conversion commissioning
J2 of frequency converter is set to "off". The frequency converter of circulating pump is not set as the last address
set 99 groups of parameters through the control panel
9901 to 0, 9902 to "5", "hand/auto"
9903 to 380, 9906 to "1"
9907 to "50", 9908 to "2900"
9909 to "37"
set communication function 53 group number setting
5302 to "2", 5303 to 9.6kbits/s
5304 to "1"
53 group parameter setting should be the same as the communication protocol setting in PLC
set here as "8", ”1 "R", the address is set to "1"
98 group parameter setting JZ is set to "off"
9802 is set to "1" Start the corresponding method of standard mod
frequency converter and PLC communication register
frequency converter register address PLC given address corresponding setting remarks
1102 external control 1/external control 2 select 4001 8
1103 external control 1 given AI 40 will have good friction performance even if the temperature is very high 02 -32676~ 32676 reference 1108 setting
0102 speed 40102
0103 output frequency 40103
0104 current 40104
0301 bus status word bit 0 40301 bit 0
starting method of frequency converter
PLC sends data to frequency converter 4001:
move 5 to 4001
Move 7 to 4001;
Move 15 to 4001;
Move 47 to 4001;
Move 101 to 4001;
at this time, the frequency converter starts and sends the speed signal to AI 4001 of the frequency converter through the bus. The speed signal of the frequency converter is controlled by PLC according to the secondary water supply and return pressure difference of the thermal power station, that is, the secondary water supply flow signal. The control of the water supply and return pressure difference realizes the real-time control of the flow
6 control of make-up water pump
the frequency converter of ABB acs-510 3KW fan pump load is used for make-up water frequency conversion. The parameter setting of the make-up water frequency converter is very similar to that of the circulating pump, but its address is set to "3", the J2 of the frequency converter is set to "on", and the make-up water frequency converter is the last device of Modbus bus
the speed control signal of the water replenishing frequency converter is sent to "4003" of the frequency converter by PLC to ensure the secondary constant pressure hot water supply. Take amplification, collection, closed-loop control
through the circulating pump of the thermal power station and the frequency converter to realize the heat quantity adjustment, it shows that the energy-saving effect of acs-510 frequency converter (3) is very obvious. Using acs-510 frequency converter to control the make-up frequency converter to reduce the heat imbalance and save water. Using acs-510's own MODBUS bus to control the operation of the frequency converter saves the equipment investment of the thermal power station, and uses bus control to reduce many external components