This system realizes automatic monitoring of the ground source heat pump air conditioning system for the nuclear power pump valve manufacturing base project, with the fundamental goal of meeting the cooling and heating needs of end users while ensuring safe, reliable, and economical operation of the system. By utilizing advanced equipment and technologies such as programmable logic controllers, industrial fieldbuses, and variable flow control, we aim to strengthen the management of numerous electromechanical devices, enabling the system to operate at its optimal conditions and achieve economic performance.

There is a monitoring room in the equipment room, which is equipped with a programmable automatic control system with independent processing capability. The software is programmed with a flexible and convenient human-machine interface to monitor the system in real time. The system can automatically collect and monitor the status of various monitoring equipment, as well as signals such as temperature and cooling capacity at monitoring points. All monitored equipment is always in optimal operating condition under the unified management of PLC, and equipment faults are reported and dealt with in a timely manner to extend the service life of the equipment. Programmable controllers have the functions of device linkage control, operation priority selection, schedule operation control, and orderly monitoring of related devices. Realize optimal control through certain calculations.

Monitoring principle

1. Load calculation: Install temperature sensors and flow sensors at the main supply and return pipes of the air conditioner to calculate the cooling and heating load of the air conditioner. And accumulate the winter and summer air conditioning load usage.

Install temperature sensors and flow sensors at the main water supply and return pipe of the air conditioning deep well, calculate the cooling and heating amounts, and accumulate the cooling and heating amounts in winter and summer.

2. Control of heat exchange well water system: There are 7 sets of heat exchange well water systems, and electric butterfly valves are installed at the outlet of each set of heat exchange well water systems. When the system is partially loaded, some of the well water systems and the corresponding water pumps of the host are turned off. The control system is set with two control methods: customized and load calculation. Load calculation method: Based on the supply and return water temperature sensors and flow sensors installed in the main pipe, the end user load demand is automatically calculated to determine the number of groups to turn on the water pump and heat exchange well, and the opening and closing of each group is determined according to the time mechanism; Opening sequence: electric valve → air conditioning water pump; Close the opposite.

3. Equipment operating time mechanism: Each water pump, cooling tower, and heat exchange well system must pay attention to balanced use. In addition to balancing the usage time of equipment in the same group as much as possible, it is also necessary to balance the number of equipment starts and avoid equipment downtime for too long.

4. Differential pressure bypass valve control: A differential pressure sensor is installed between the air conditioning supply and return water units. Based on the measured differential pressure signal and the set differential pressure signal, the differential pressure bypass valve opening is automatically calculated using PID to ensure a constant pressure difference between the supply and return water.

5. Variable frequency control of water pumps: Three sets of variable frequency systems are installed for three air conditioning water pumps, and three sets of variable frequency systems are also installed for the three water pumps on the ground source side. The speed of the water pumps is automatically adjusted according to the difference in supply and return water pressure, in order to achieve linear adjustment of the air conditioning water volume under partial load of the air conditioning system and save energy. The hot water pump is equipped with a frequency converter and another water pump as a backup. The frequency converter frequency is automatically adjusted by the hot water supply pressure to achieve energy saving.

6. Control of cooling water pump and cooling tower: automatic start stop of cooling tower. Ultimately achieving a balance of soil heat intake and discharge throughout the year.

When the weather is hot during the day, the ground source side should be prioritized for activation. When the temperature is lower at night, it is beneficial for the cooling tower to exchange heat. Based on the signal transmitted by the soil temperature sensor and energy-saving optimization program

7. Equipment activation sequence

Refrigeration: Ground source side circulating water pump, chilled water circulation pump, chiller unit, cooling water pump, cooling tower

Heating: Ground source side circulating water pump, chilled water circulating pump, chiller unit

8. The temperature difference of buried pipe heat exchange in winter is much smaller than that in summer, which can cause soil temperature rise and soil thermal pollution over the years. Therefore, by monitoring the data of one soil temperature sensor per buried pipe, a combination of constant temperature difference and constant pressure difference control is adopted on the ground source side. This excellent control method is used to control the cold source to balance the heat.