emerging globally using switched reluctance technology
Constant pressure water supply system
(HVAC, urban water supply, constant pressure water supply for industrial enterprises)
With the development and maturity of the switched reluctance motor control technology, the constant pressure water supply (water injection) systems of cities and industrial enterprises have been able to achieve systematic intelligent operation, energy saving, cost reduction, performance improvement and reliability improvement. At present, western developed countries led by the United States are implementing a constant pressure intelligent water supply system driven by switched reluctance motors, from building HVAC to water supply in the industrial field, and linking with cloud service platforms to achieve an annualized comprehensive power saving rate Reached 45%, and basically realized unattended.
1. Basic hardware composition and function of switched reluctance constant pressure water supply system
1. Switched reluctance motor
Replace the original motor with an advanced switched reluctance motor to drive the water pump. Its advantages are described later.
2. Switched reluctance motor intelligent controller
The intelligent controller drives the switched reluctance motor to drive the pump to run, communicates with PLC and pressure sensor in real time, and freely controls the output speed, torque and other elements of the switched reluctance motor;
3. Pressure transmitter
It is used to monitor the actual water pressure of the pipe network in real time and transmit data to the intelligent controller of the motor.
*4.PLC and other components
PLC is used for the control of the entire upper system. Other necessary equipment and sensors, such as liquid level transmitters, system monitoring platforms, etc., are increased or decreased according to the needs of different systems.
2. Basic principle of switched reluctance constant pressure water supply system
The actual change of pressure in the water pipe network leading to the user is collected through the pressure sensor and transmitted to the motor intelligent controller. The controller compares and processes it with the given value (set value), and adjusts it according to the data processing results. Output characteristics such as the speed of the motor (pump). When the water supply pressure is lower than the set pressure, the controller will increase the operating speed, and vice versa. And the differential self-adjustment is carried out according to the speed of the pressure change. The whole system can be closed-loop automatic control, and the motor speed can also be manually adjusted manually.
3. Basic functions of constant pressure water supply system
(1) Keep the water pressure constant;
(2) The control system can automatically/manually adjust the operation;
(3) Automatic switching operation of multiple pumps;
(4) The system sleeps and wakes up. When the outside world stops using water, the system is in a sleep state and automatically wakes up when there is a demand for water;
(5) Online adjustment of PID parameters;
(6) Online monitoring of motor speed and frequency
(7) Real-time monitoring of the communication status of the controller and PLC;
(8) Real-time monitoring of alarm parameters such as overcurrent and overvoltage of the controller;
(9) Real-time monitoring of pump set and line protection detection alarm, signal display, etc.
Fourth, the technical advantages of the switched reluctance constant pressure water supply system
Compared with other constant pressure water supply methods (such as variable frequency constant pressure), the switched reluctance constant pressure water supply system has the following obvious advantages:
(1) More significant energy saving effect. It can achieve an annual comprehensive power saving rate of 10%-60%.
(2) The switched reluctance motor has higher starting torque and lower starting current. It can start with 1.5 times the torque load at 30% of the rated current. It’s a real soft starter. The motor accelerates freely according to the set acceleration time, avoiding the current impact when the motor starts, avoiding the fluctuation of the power grid voltage, and avoiding the surge of the pump system caused by the sudden acceleration of the motor. Eliminate water hammer phenomenon.
(3) It can make the switch reluctance motor wider speed regulation, and the overall efficiency is higher in the whole speed regulation range. It has excellent output characteristics such as torque in the medium and low speed area below the rated speed and above tens or hundreds of revolutions. It can adjust the speed of the pump with a large speed ratio, making the pump an intelligent device. It can freely change the outlet pressure of the pump, reduce pipeline resistance and reduce interception loss. efficiency is more obvious.
(4) The pump can be changed more freely. When the outlet flow is less than the rated flow, the pump speed is reduced, the bearing wear and heat are reduced, and the mechanical service life of the pump and motor is prolonged.
(5) Automatic constant pressure control, removing other pressure regulating equipment, and providing Internet of Things and Internet interfaces to support the realization of the intelligence of the entire system. The system does not require frequent operation by operators, which greatly reduces the labor intensity of personnel and saves manpower.
(6) The reliability and service life of the switched reluctance motor drive system are higher. Daily inspections and maintenance are done as required, and the entire system can run continuously without failure for a long time.
The following two figures show the continuous high-efficiency characteristics and continuous high-torque characteristics of the switched reluctance drive system in a very wide speed regulation range.
Switched reluctance motors can reduce power consumption by more than 60% every year in the intelligent energy saving of building systems (HVAC).
*5. Other parts of the constant pressure water supply system (selection): host monitoring
5.1 Real-time monitoring
System main interface
The working status of each part of the switched reluctance motor, switched reluctance motor controller, PLC and pressure sensor is displayed by means of graphics and text.
The main interface displays the current motor speed, working frequency, pressure value, PID and other parameters in real time. The motor will automatically adjust the speed according to the real-time pressure value, or it can be manually adjusted by the host. When the controller or motor works abnormally, the corresponding position will pop up the alarm date and fault description.
5.2 Real-time alarm
5.3 Real-time curve
5.3 Data report
Six, constant pressure water supply application field
1. Tap water supply, living quarters and fire-fighting water supply systems can also be used for hot water supply, constant pressure spraying and other systems.
2. Industrial enterprise production, domestic water supply system and other fields that require constant pressure control (such as constant pressure air supply and constant pressure air supply of air compressor system). Constant pressure, variable pressure control, cooling water and circulating water supply systems in various occasions.
3. Sewage pumping station, sewage treatment and sewage lifting system.
4. Agricultural irrigation and garden spraying.
5. Water supply and fire-fighting systems in hotels and large public buildings.
Switched reluctance constant pressure water supply system has the advantages of more energy saving, more reliable and more intelligent. At present, it is more and more widely used, not only can be used in the HVAC of schools, hospitals, living quarters, but also in the constant pressure water supply or water injection required by various industrial enterprises, such as cooling water circulation, constant pressure water injection in oil fields, etc. . The switched reluctance constant pressure water supply system not only saves electricity and water, but also greatly improves the working performance of the system and prolongs the service life. It is a system that combines economic benefits and technical value, and has broad application prospects.
1. Building system (HVAC) energy saving
Building heating, ventilation and air conditioning (HVAC) is an important unit of electricity consumption. However, the current application of energy-saving technologies in this field in my country is limited, so there is great potential for energy-saving upgrades. 70% of the electric energy in this field is consumed by the motor, so replacing the motor with high energy saving is a relatively straightforward solution.
2. Characteristics of switched reluctance motors for building heating and ventilation (HVAC)
Building HVAC HVAC systems include heating, ventilation, and air conditioning systems. The motors used in circulating pumps, fans, and air conditioners should objectively have variable load and speed regulation characteristics. However, due to technical and traditional reasons, most building HVAC systems are currently used. The motors of the HVAC system run at constant speed and light load, which are seriously out of the actual working conditions and have low efficiency, resulting in a huge waste of electric energy. Therefore, it is an economical and practical choice to replace the switched reluctance motor with a powerful function of variable load speed regulation.
The switched reluctance motor for building heating and ventilation (HVAC) developed by our company has the following performance characteristics:
a wide range of effective speed regulation, low-speed and ultra-low-speed regions maintain efficiency and large torque. It can meet the all-day adjustment of building motors. speed and load regulation.
Under light load conditions, the current loss of the motor is very small. The light load state is an inevitable adjustment and demand made by the building HVAC system according to seasonal changes.
When the equipment is running without load, the current of the motor is kept below 1.5 A. Almost no power consumption.
The following is the measured performance data of the 22kw (750 rpm) switched reluctance motor commonly used in building systems developed by our company (authoritative third-party testing):
Laboratory test data of a 22kw 750rpm mass-produced switched reluctance motor.
When the switched reluctance motor is under no load, the current of the motor is kept below 1.5 A. Almost no power consumption.
This also explains the excellent output characteristics of this motor under variable load and variable speed conditions: energy saving does not depend on how high the rated efficiency is, but on the ability to adapt to the working conditions.
Our company provides the switched reluctance motor solution for the American SMC company (providing switched reluctance motors for the American building HVAC system).