Energy-saving control method of online water quality automatic sampler

Abstract

The application provides an energy-saving control method of an online water quality automatic sampler. The intelligent control of a refrigeration unit is realized through sampling state and weighing feedback, so that the energy-saving effect is achieved, and the temperature control precision is improved. When the water quality automatic sampler control unit is in standby state and sampling is completed, the control unit outputs a digital signal to the refrigeration unit through a port, so that the refrigeration unit is not powered on. When the water quality automatic sampler control unit is in running state and sampling is completed, the control unit controls the refrigeration unit to output a digital signal to the refrigeration unit through a port, so that the refrigeration unit is powered on and started. The refrigeration unit will complete the refrigeration of the water sample at a preset temperature. The refrigeration unit in the running state will run according to the energy-saving control algorithm of the sampling weight.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water quality sampling equipment, in particular to an energy-saving control method of an online water quality automatic sampler. BACKGROUND

[0002] The water quality automatic sampler is an intelligent water quality sampling equipment, which can realize sampling of water bodies and is used for subsequent water quality detection and analysis to determine water pollutant concentration, and is a necessary link in environmental monitoring.

[0003] The refrigeration unit of the water quality automatic sampler is one of the main components of power consumption, and long standby operation will increase power consumption. At present, the water quality automatic samplers on the market have water sample refrigeration function, and the water sample refrigeration unit and the sampler are powered on at the same time. When there is no water sample to be saved in the refrigeration unit, the refrigeration unit is turned on, which will produce invalid power consumption. The traditional water quality automatic sampler usually adopts a continuous refrigeration operation mode, so that even in the case of no sampling, the refrigeration unit remains in the working state, causing a large amount of power waste. In the actual use process of the water quality automatic sampler, most of the water quality automatic samplers are in standby state for a long time, and there is no water sample saved in the refrigeration unit, and the refrigeration unit is in an empty bottle state. At this time, the refrigeration unit is still in the working state, which on the one hand produces unnecessary power consumption, and on the other hand, in order to maintain the refrigeration temperature, the compressor will continuously start and stop to maintain the set temperature in the refrigeration unit, which affects the service life of the compressor.

[0004] There is a lack of effective energy-saving control scheme in the prior art, which cannot dynamically adjust the working mode of the refrigeration unit according to the actual sampling state. In addition, the temperature control precision of the existing sampler is insufficient, and the power control cannot be performed according to the sampling amount, so that the best energy efficiency ratio cannot be achieved.

[0005] Chinese patent CN202210609176.1 discloses a drainage pipe network runoff water quality analysis and monitoring method and system, which comprises the following steps: S1, controlling multiple water quality analyzers to switch operation to generate continuous water quality data of the front pool water body; S2, controlling each valve in the flow path sequencing component at the inflow port of the front pool according to the flow path sequencing equation set and the collected data; S3, calculating the water quality data of the three-path flow in combination with the continuous water quality data and the control signals of each valve; S4, marking and positioning the tributary path causing the water quality data to exceed the standard based on the runoff with exceeding water quality data and the inflow path of the front section of the runoff; and S5, performing corresponding processing based on the calculated water quality data of the three-path flow. However, there is a lack of real-time monitoring of multi-source runoff water quality changes, which makes it difficult to locate the pollution point when the water quality exceeds the standard, and the existing technology has high modification cost and is difficult to realize accurate pollution source positioning and processing, and cannot be energy-saving controlled.

[0006] Therefore, it is particularly important to design an online water quality automatic sampler which can reduce power consumption when the automatic sampler is in standby state and does not sample and store samples, and the refrigeration unit does not work, and can achieve the best energy efficiency ratio when the refrigeration unit works and the refrigeration power is controlled according to the sampling amount. SUMMARY

[0007] The application provides an energy-saving control method of an online water quality automatic sampler, which realizes intelligent control of a refrigeration unit through sampling state and weighing feedback, achieves energy-saving effect, and improves temperature control precision.

[0008] To achieve the above object, the technical solution of the application comprises two layers of logic, a first layer of control logic: refrigeration unit start-stop control based on sampling state. In the waiting sampling stage (standby state), the refrigeration unit is not powered on and is in a power-off state under the control of the control unit; in the water sampling stage (running state) and the water sampling completion stage (completion state), the refrigeration unit is powered on and is in a power-on state under the control of the control unit; the control unit controls the refrigeration unit to be powered off in the standby state of the next cycle when the sampling is completed. The second layer of control logic: energy-saving control algorithm based on sampling weight.

[0009] In the first aspect, the application provides an energy-saving control method of an online water quality automatic sampler, wherein the sampler has a control unit and a refrigeration unit, and the method comprises the following steps:

[0010] When the working state of the sampler is determined to be in standby state or sampling state, the control unit outputs a low-level signal to make the refrigeration unit stop running by being powered off;

[0011] When the working state of the sampler is in running state or completion state, the control unit outputs a high-level signal to make the refrigeration unit start running by being powered on;

[0012] The current mass of the water sample in the sampler is acquired in real time, and the ratio of the current mass to the maximum capacity of the sampler is calculated;

[0013] According to the ratio and a preset adjustment coefficient, the refrigeration power is dynamically adjusted through a nonlinear function relationship, so that the refrigeration power increases according to a power function law with the increase of the current mass;

[0014] According to the ratio and a preset lowest temperature and highest temperature range, the temperature set value of the refrigeration unit is dynamically adjusted, so that the temperature set value transitions from the lowest temperature to the highest temperature according to an exponential function law with the increase of the current mass;

[0015] Based on the proportion, the proportional coefficient, the integral coefficient and the differential coefficient are independently adjusted, including the proportional coefficient increases at a first exponential rate with the increase of the current mass; the integral coefficient increases at a second exponential rate with the increase of the current mass, and the increasing speed is lower than that of the proportional coefficient; the differential coefficient increases at a third exponential rate with the increase of the current mass, and the increasing speed is higher than that of the proportional coefficient.

[0016] According to the adjusted PID parameters, the closed-loop temperature control is performed to stabilize the temperature of the refrigeration unit at the temperature set value.

[0017] Preferably, in the dynamic refrigeration power adjustment, the calculation formula of the refrigeration power is:

[0018]

[0019] Wherein, P is the current refrigeration power, P max is the maximum refrigeration power, m is the current sampling mass, m max is the maximum capacity of the sampler, and a is the adjustment coefficient, which is in the range of 0.5 to 1.5.

[0020] Preferably, the calculation formula of the temperature set value is:

[0021]

[0022] Wherein, T set is the current temperature set value (unit: ℃), T min is the preset minimum temperature set value, which is 2 ℃, T max is the preset maximum temperature set value, which is 6 ℃, m is the current mass of the water sample in the sampler (unit: kg), and m max is the maximum capacity of the sampler (unit: kg).

[0023] Preferably, in the improved PID parameter dynamic adjustment, the calculation formulas of the proportional coefficient, the integral coefficient and the differential coefficient are respectively:

[0024]

[0025] Wherein, K p0 , K i0 , K d0 are the initial PID parameters.

[0026] Preferably, the value of the adjustment coefficient a is 0.8 to 1.2, preferably 1.0.

[0027] Preferably, the minimum temperature set value T min is 2 ℃, the maximum temperature set value T max is 6 ℃, and the exponential of the temperature transition exponential function is 0.3.

[0028] Preferably, the first exponential rate is 0.8, the second exponential rate is 0.5, the third exponential rate is 1.2, and the initial PID parameters are determined by experimental calibration of the refrigeration unit model.

[0029] Preferably, the refrigeration unit is a semiconductor refrigeration module, the maximum refrigeration power is 200-500W, and the maximum capacity of the sampler is 1-5kg.

[0030] Preferably, the control unit integrates a weighing sensor with a range of 0-5kg and an accuracy of ±0.1%, and a temperature sensor of PT100 type with an accuracy of ±0.2℃.

[0031] In a second aspect, the application provides an online water quality sampler for implementing the energy-saving control method of the online water quality automatic sampler as described in the first aspect, comprising a sampling mechanical unit, a refrigeration unit, a control unit, a weighing feedback unit, a power module, a communication module, a user interaction module, an alarm module, and an auxiliary function unit.

[0032] The technical solution has the following beneficial effects:

[0033] Significant energy-saving effect: through the double-layer control logic of sampling state and weighing feedback, the refrigeration unit works on demand with high energy efficiency ratio. Accurate temperature control: dynamic PID control algorithm is adopted for accurate temperature control. High degree of intelligence: standby state, running state, completion state, and sampling process are intelligently controlled. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is the control unit of an embodiment of the application controlling the start-stop logic of the refrigeration unit.

[0035] Figure 2 is a structural schematic diagram of the energy-saving online water quality automatic sampler of an embodiment of the application. DETAILED DESCRIPTION

[0036] The application will be further described below in conjunction with embodiments and drawings.

[0037] As shown in Figure 1 After the energy-saving online water quality automatic sampler is installed, it is connected to power and set to sampling mode. In the water sample sampling stage (running state) and the water sample sampling completion stage (completion state), the refrigeration unit is powered on by the control unit to provide refrigeration temperature for the collected water sample. The control unit controls the refrigeration unit to be powered off in the standby state of the next cycle when the sampling is completed.

[0038] Energy-saving control algorithm based on sampling weight. Refrigeration power adjustment: calculate refrigeration power P according to sampling mass m; adjust refrigeration power according to temperature deviation ΔT = T set -T actual Adjust PID parameters; temperature control: execute PID control algorithm, adjust refrigeration power, and maintain set temperature.

[0039] In another embodiment, the embodiment takes the monitoring of the effluent outlet of a certain municipal sewage treatment plant as an example, and needs to continuously sample and refrigerate the discharged water for 24 hours for subsequent pollutant concentration analysis. The system is deployed beside an outdoor manhole and needs to adapt to high temperature and humid environment and meet the requirements of unattended operation, remote monitoring and low power consumption.

[0040] First step, the control unit (STM32F407 microcontroller) starts the sampling process according to the preset schedule (e.g. once every hour) or external trigger signal (e.g. flow meter detects water flow mutation). The sampling mechanical unit starts working, and the sampling pump (diaphragm pump, flow rate 2L / min) extracts water samples from the water body through corrosion-resistant silicone hose. The switching valve (electric three-way valve) guides the water sample to the designated sampling bottle (12-bottle rotary split rack) to avoid cross contamination of samples at different times. Then the auxiliary unit intervenes, and the pre-filter (50μm stainless steel filter screen) removes suspended particles to protect the pipeline and pump body. The flow meter (accuracy ±1%) monitors the sampling volume in real time to ensure that each bottle of water sample is 500±10mL. Automated sampling reduces human intervention; multi-bottle split design supports long-term monitoring; and the filtration system prolongs the service life of the equipment.

[0041] Second step, the weighing feedback unit intervenes: the weighing sensor (range 0-5kg, accuracy ±0.1%) measures the mass in the sampler (m = 2.5kg, m max = 5kg) in real time. The control unit dynamically adjusts the refrigeration power according to the formula P = 500 × (2.5 / 5) 1.0 = 250W. Then the refrigeration unit responds: the semiconductor refrigeration module (TEC1-12706) starts at a power of 250W, and the box temperature starts to drop from the ambient temperature of 30℃, and the temperature sensor (PT100) continuously feeds back the actual temperature to the control unit. It can realize on-demand power adjustment, the power consumption is 0W when idle, and the energy-saving rate reaches 60%; avoids frequent start-stop of the compressor, and prolongs the service life of the equipment.

[0042] Third step, dynamic PID temperature control and temperature setting, the control unit sets the target temperature according to the formula T set = 2 + (6-2) × (2.5 / 5) 0.3 ≈ 3.8℃. Then the PID parameters are dynamically adjusted, the proportional coefficient K p = K p0 × (2.5 / 5) 0.8 = 0.6Kp0 , K i = K i0 x (2.5 / 5) 0.5 = 0.7K i0 , K d = K d0 x (2.5 / 5) 1.2 = 0.4K d0 . Then closed-loop control is executed, if the actual temperature deviates from the set value (such as detecting T = 4.5℃), the PID algorithm outputs an adjustment signal to increase the refrigeration power, gradually stabilize to 3.8±0.3℃. It can realize dynamic PID to improve temperature control precision (fluctuation ≤±0.5℃), avoid sample deterioration caused by overcooling or temperature rise.

[0043] The above specific embodiments are only used to explain and illustrate the present application, and not to limit the present application, any changes and substitutions of the present application without creative labor within the concept and protection scope of the claims of the present application, all fall within the protection scope of the present application patent.

Claims

1. An energy-saving control method for an online water quality automatic sampler having a control unit and a refrigeration unit, characterized by, Comprising: When the sampler is determined to be in standby state or sampling state according to its working state, the control unit outputs a low-level signal to stop the operation of the refrigeration unit; When the sampler is in running state or completion state, the control unit outputs a high-level signal to start the operation of the refrigeration unit; Real-time acquisition of the current quality of the water sample in the sampler, and calculation of the proportion of the current quality to the maximum capacity of the sampler; According to the proportion and the preset adjustment coefficient, the refrigeration power is dynamically adjusted through a nonlinear function relationship, so that the refrigeration power increases with the increase of the current quality according to a power function law; According to the proportion and the preset minimum temperature and maximum temperature range, the temperature set value of the refrigeration unit is dynamically adjusted, so that the temperature set value transitions from the minimum temperature to the maximum temperature according to an exponential function law with the increase of the current quality; Based on the proportion, the proportional coefficient, the integral coefficient and the differential coefficient are independently adjusted, including that the proportional coefficient increases according to a first exponential rate with the increase of the current quality; the integral coefficient increases according to a second exponential rate with the increase of the current quality, and the increasing speed is lower than that of the proportional coefficient; the differential coefficient increases according to a third exponential rate with the increase of the current quality, and the increasing speed is higher than that of the proportional coefficient; According to the adjusted PID parameters, closed-loop temperature control is performed to stabilize the temperature of the refrigeration unit at the temperature set value.

2. The energy saving control method of an online water quality autosampler according to claim 1, characterized by, In the dynamic refrigeration power adjustment, the calculation formula of the refrigeration power is: ； Wherein, P is the current refrigeration power, P max is the maximum refrigeration power, m is the current sampling quality, m max is the maximum capacity of the sampler, and a is the adjustment coefficient, the value range is 0.5 to 1.

5.

3. The energy saving control method of an online water quality autosampler according to claim 1, characterized by, The calculation formula of the temperature set value is: ； Among them, T set Current temperature setting, unit: °C, T min The preset minimum temperature setting is 2℃, T max The preset maximum temperature setting is 6℃, and m is the current mass of the water sample in the sampler, in kg / m. max This represents the maximum capacity of the sampler, in kg.

4. The energy saving control method of an online water quality autosampler according to claim 3, characterized in that, In the independent adjustment of the proportional coefficient, the integral coefficient and the differential coefficient based on the proportion, the calculation formulas of the proportional coefficient, the integral coefficient and the differential coefficient are respectively: ； ； ； where K p0 , K i0 , K d0 are initial PID parameters.

5. The energy-saving control method of the online water quality automatic sampler according to claim 1, wherein the value of the adjustment coefficient α is 0.8 to 1.

2.

6. The energy saving control method of an online water quality autosampler according to claim 1, characterized by, the minimum temperature set value T min is 2°C, the maximum temperature set value T max is 6°C, and the exponential of the exponential function of the temperature transition is 0.

3.

7. The energy saving control method of an online water quality autosampler according to claim 1, characterized by, The first exponential rate is 0.8, the second exponential rate is 0.5, and the third exponential rate is 1.2, and the initial PID parameters are determined by experimental calibration of the refrigeration unit model.

8. The energy saving control method of an online water quality autosampler according to claim 1, characterized by, The refrigeration unit is a semiconductor refrigeration module, and the maximum refrigeration power is 200-500W. The maximum capacity of the sampler is 1-5kg.

9. The energy saving control method of an online water quality autosampler according to claim 1, characterized by, The control unit integrates a weighing sensor with a range of 0-5kg and an accuracy of ±0.1%, and a temperature sensor of PT100 type with an accuracy of ±0.2℃.

10. An online water quality sampler for implementing the energy-saving control method of the online water quality automatic sampler according to any one of claims 1-9, comprising a sampling mechanical unit, a refrigeration unit, a control unit, a weighing feedback unit, a power module, a communication module, a user interaction module, an alarm module and an auxiliary function unit.

Images