CN1561675A - Room temperature environment control technology based on economic optimum - Google Patents

Abstract

The invention relates to the technical fields of agricultural biological environmental engineering and _protected gardening. It establishes the relationship between environmental factors and Crop growth database, control effect database. Then set a period of time, select one of the control mechanisms such as ventilation, cooling, dehumidification, humidification, heating, etc., use the control effect database to calculate the expected regulation and control of environmental factors that can be achieved within the set period of time, and at the same time calculate The control cost P consumed by the action of the internal mechanism; and then calculate the economic output value C of the crop; through calculation and selection of the largest C/P value, determine the combination of different action states of the control mechanism with the economical optimum as the control goal. completed control scheme. It regulates crops in stages, which can effectively reduce the control cost of greenhouse operation and improve the economic benefits of modern greenhouse production.

Description

Greenhouse Environmental Control Technology Based on Economic Optimum

technical field

The invention relates to the technical fields of agricultural biological environment engineering and protected gardening, in particular to the greenhouse environment control technology aiming at economic optimization.

Background technique

One of the main characteristics of modern greenhouse production is that according to the outdoor meteorological conditions and the growth and development stages of crops, environmental control equipment can be used to effectively control the environmental conditions in the greenhouse, and continuous production and management methods can be used to efficiently and balancedly produce various crops. Vegetables, fruits, flowers, herbs, etc.

There are many factors affecting the growth and development of crops in the greenhouse, mainly involving water, nutrients, temperature, light and humidity. In order to obtain the maximum production profit or the economic output of crops, these environmental factors that affect the growth and yield of crops must be effectively controlled, and at the same time, the costs of greenhouse operations that must be paid for these controls and the implementation of crops must be considered. The corresponding increase in growth under the control means, that is, the economic output of the crop.

At present, our country has carried out extensive and active exploration and research in the aspects of automatic control of greenhouse environment and intelligent management, and put forward strategies and means of implementing environmental control in greenhouses, such as greenhouse fuzzy control system and BP neural network control system, etc., which will promote my country's The development of facility agriculture has played a positive role. However, in the actual control process, the growth state and process of crops have not been combined, and the interaction between crop growth and greenhouse environment has not been organically combined. At the same time, the mechanism of crop growth and development and yield formation in the greenhouse have not been deeply and effectively studied Substantive research has affected the practicability of these research results to varying degrees. The greenhouse environment cannot achieve high-yield and high-efficiency comprehensive control, and the control accuracy and stability are poor. my country's facility environment control technology mainly adopts single-factor control, which fails to solve the problem of mutual coupling of environmental factors. A large number of operations and adjustments in the greenhouse require manual operation and adjustment, the degree of control of crop growth environmental factors is very low, and the operating cost of the entire greenhouse is very high.

Greenhouse environmental optimization control technology and control objectives have always been the research focus of foreign agricultural engineering circles. The TOMGRO model proposed by J.W.Jones (1991) uses the change relationship of crop carbon sink strength to seek the distribution relationship of crop dry matter, so as to find the formation mechanism of crop yield. Chalcbi (1992), Hwang (1993), Van Henten (1994, 2003), Seginer (1998), Tap (2000) etc. conducted research on common crops such as tomato and lettuce in the greenhouse, and the environmental management in the greenhouse Optimal control proposes a control strategy. The strategy mainly considers the economic interests of the growers, takes the net income of the crop growth process as the optimization goal, and based on the planting data of five to ten years, uses the Maximum Principle of Pontryagin to analyze the Hamilton Function (Hamiltonian) optimization, to determine the control means that users in the greenhouse can control and obtain benefits, so as to manage the operation of the greenhouse and the normal growth and development of crops. But the whole control process is concentrated in the crop reproductive growth stage (lettuce is in the whole growth stage), and the calculation formula is very complicated, and the required data and coefficients are very diverse. Burhan Ozkan (2004) conducted research on the greenhouse industry in Turkey, and analyzed the input and output of vegetable cultivation in greenhouses, but the main focus was on the analysis of the cost and output of each vegetable planted. Provides guidance to growers in selecting crop types in the greenhouse. Through inquiries, there is currently no patent application for greenhouse environment control technology based on economical optimization, and foreign patents are mainly reflected in new types of greenhouse structures and greenhouse equipment, crop growth systems and cultivation methods.

Contents of the invention

The purpose of the present invention is to provide an environment control technology based on economic optimization for the agricultural facility greenhouse.

The purpose of the present invention is to realize through the following technical solutions:

The greenhouse control mechanism adopted in the present invention includes: skylight, side window (or roller shutter, divided into east, west, south, north), sunshade net, fan, wet curtain or spray, heat preservation curtain, heater and its opening and closing mechanism .

First, measure the crop growth under different environmental factors such as temperature, light, and carbon dioxide concentration, measure the environmental factor parameters achieved by each control mechanism in the greenhouse, and establish a database of environmental factors and crop growth, and a database of control effects .

Then set a period of time (usually 10-30 minutes), select one of the control mechanisms such as ventilation, cooling, dehumidification, humidification, and heating, and use the control effect database to calculate the expected environmental factors that can be achieved within the set period of time. control amount, and calculate the control cost P consumed by the mechanism action within this time;

Then, according to the expected control amount of the obtained environmental factors, the economic output value C of the crop is calculated by using the database of crop growth;

Then calculate the C/P value;

Finally, repeat steps b, c, and d above to find the maximum value of the C/P values that may be generated under the individual and combined actions of all control mechanisms in the greenhouse implemented. The greenhouse control mechanism action corresponding to the maximum value is The control scheme required by the economical optimum as the control objective.

A better technical solution is to divide the entire growing season of crops into a vegetative growth stage and a reproductive growth stage. When the crops are in the vegetative growth stage, the environmental regulation of the greenhouse is based on the temperature priority technical solution to ensure that the crops are in a suitable growth environment. Reduce control costs. For example, the suitable growth temperature (day/night) of four main greenhouse crops is set as: lettuce 15～20/12～15℃, sweet pepper 22～25/14～20℃, tomato 20～30/15～20℃, cucumber 21～27/19～24℃. When the crops are in the reproductive growth stage, the control system realizes the regulation and control of the environmental parameters in the greenhouse according to the economical optimal regulation method.

When the crops are in the stage of reproductive growth, the implementation of the economically optimal environmental control technology plan is as follows: firstly, judge whether the current environmental parameters of the greenhouse meet the suitable range of crop growth, and if so, maintain the current control mechanism of the greenhouse. If it is satisfied, the above-mentioned step of calculating the ratio C/P of the economic output value of the crop to the control cost consumed by the organization's action is to select the best control scheme with the economic optimum as the control goal by finding the maximum value.

At night, the environmental regulation of the greenhouse can adopt the night control scheme, which is based on the average control effect level during the day, and is controlled by the improved diurnal temperature difference method. In order to facilitate the effective delivery of crop photosynthetic products during the day, the environment in the greenhouse in the first half of the night is controlled at a level slightly higher than the average control effect level during the day minus a set value, while in the second half of the night, it is based on the minimum limit temperature of crops plus a set value. It is controlled at a fixed value to help reduce the energy consumption of the entire system and reduce the production cost of the greenhouse.

The advantages of the present invention are:

The comprehensive system analyzes the economic input and crop economic output of the entire operation of the greenhouse. According to the different requirements for the environmental conditions of different varieties of crops planted in the greenhouse, and the same variety has different requirements in different growth stages, the crops are regulated by stages. , combined with the control cost of maintaining the operation of the greenhouse, the economical optimal environmental control method can better meet the needs of the factory production of crops, and improve the economic benefits of modern greenhouse production.

Description of drawings

Figure 1 shows the greenhouse environment control algorithm aiming at economical optimization

Figure 2 is a flow chart of the environmental control of the greenhouse at night based on the diurnal temperature difference method

In Figure 2, the meaning of each parameter is as follows:

_Inside T is the temperature value measured in the greenhouse after the operation of the control equipment;

T3=T0+T _assumes . T0 is the low temperature critical temperature value of the crop; T _{is set as} the set value, generally T should _{be set to} ≥ 1-2°C

T _is the average temperature of the greenhouse during the day; It is the temperature difference value set according to the diurnal temperature difference method, which is generally 4-8°C, and the difference value can also be determined according to the suggestions of planting experts;

T2=T1+T _assumes .

Detailed ways

The technical solution and implementation mode of the present invention will be further described below by taking cucumber, one of the main fruits and vegetables grown in the current agricultural facility horticulture, as an example.

First, measure the crop growth under different environmental factors such as temperature, light, and carbon dioxide concentration, measure the environmental factor parameters achieved by each control mechanism in the greenhouse, and establish a database of environmental factors and crop growth, and a database of control effects .

Take cucumber as an example, about 40 days after planting, as the vegetative growth stage of cucumber, 40 days later until the end of the harvest period, as its reproductive growth stage.

Through cultivation experiments, the proportion of dry matter produced by photosynthesis of cucumber planting for 40 to 50 days is 0.018 to 0.427, and the proportion of 50 to 60 days is 0.427 to 0.527. The proportion number allocated is 0.527-0.539, and the proportion number allocated after 70 days is 0.539-0.561.

Within 40 days from the beginning of planting, cucumbers should be implemented according to the temperature priority control strategy to ensure the suitable growth of cucumbers. After 40 days, the control system transfers to the control scheme of the reproductive growth stage. For example, the operation of the system on one day: at 14:00 on this day, the temperature in the greenhouse is 35°C, the relative humidity is 47%, and the light intensity is 21.56kLx. Judging according to the control effect The operation of "cooling and humidification" is required, and all the executable mechanism combination schemes that meet the rules of "cooling and humidification" are judged and queried: internal spray, internal spray + external spray, internal spray + external spray + South roller blind, inner spray + outer spray + south roller blind + fan. One of the schemes is selected, and the control system calculates the corresponding temperature, relative humidity and light intensity changes within the set time according to the combination, that is, the expected control amount of the environmental parameters is obtained, and the temperature in the greenhouse after the set time is calculated. Environmental parameter values (temperature in the greenhouse, light intensity, relative humidity); at the same time, calculate the control cost P required for the operation of the above-mentioned executable mechanism combination scheme within the set time, and then use the expected environmental parameter values obtained just now to calculate The net photosynthetic rate Pn obtained by the cucumbers after this period of time is calculated from the fruit ratio of the corresponding growth days of the cucumbers to calculate the net increase in output value C of the crops after the set time. Divide C by P to get the Dn value, which is the ratio of output to input. Comparing the Dn values of all combinations of executable agencies for cooling and humidification, select the group with the largest Dn value as the optimal solution. In this example, the group that can achieve the best cost performance in the "cooling and humidification" operation The scheme is "internal spray" combination. Using the control effect database, the optimal solution of the program for 20 minutes is that the temperature in the greenhouse is 33.65°C, the relative humidity is 72.14%, and the light intensity remains unchanged. After 20 minutes of actual use of the "internal spray" combination, it was found that the temperature in the greenhouse was 33.8°C, the relative humidity was 71%, and the light intensity remained unchanged, which achieved the expected purpose of the system design. Reaching such environmental parameters not only ensures the needs of crop growth, but also takes into account the economic cost.

The environmental control technology of cucumber at night is based on the average control effect during the day combined with the diurnal temperature difference method. The low temperature critical temperature T0 of cucumber is 14°C, take the difference temperature According to the temperature records of the greenhouse during the day, the average temperature T of the greenhouse during the day _is 24°C. The temperature in the greenhouse in the first half of the night should be controlled between 18-20°C, and the temperature in the greenhouse in the second half of the night should be controlled above 16°C. If the average temperature T of the greenhouse during the day _is 18°C, the temperature in the greenhouse in the first and second midnight should be controlled above 14°C.

According to the above technical scheme, the corresponding control software has been compiled.

The above control methods have been proved by practice to have good operability and control effects, and can truly achieve high yield, high quality and high efficiency in greenhouse production.

Claims (3)

1. based on the Status quo of Greenhouse Environment Control Technology of economic optimum, it is characterized in that:

A. mensuration is planted the crop growth amount under the envirment factors such as crop different temperatures, illumination, gas concentration lwevel, measure the envirment factor parameter that is reached when each regulating and controlling mechanism of greenhouse is carried out, set up database, the control effect data storehouse of envirment factor and crop growth amount;

B. set a period (being generally 10-30 minute), one of controlling organization such as select ventilation, cooling, dehumidifying, humidification, heat, utilize control effect data storehouse, the pre-period regulation amount of envirment factor that can reach in the period is being set in calculating, simultaneously the interior spent P that controls cost of mechanism action between calculating at this moment;

C. according to the pre-period regulation amount of resulting envirment factor, utilize the database of crop growth amount, calculate the economic output value C of crop;

D. calculate the C/P value;

E. repeat above b, c, d step, to seeking maximum in the issuable C/P value under independent effect of all controlling organizations in the greenhouse of being implemented and the compound action, controlling organization action in the pairing greenhouse of this maximum is by economic optimum and is control target desired control scheme.

2. the Status quo of Greenhouse Environment Control Technology based on economic optimum as claimed in claim 1 is characterized in that: the growing environment control of crop is to implement different control methods by nourishing and growing with two vegetative stages of reproductive growth; Vegetative growth phase is to be undertaken by temperature prioritised control method, promptly preferentially guarantees the crop regulation and control in the preference temperature scope, and generative growth phase is realized environment control by the control scheme of ratio for input and output optimum.

3. the Status quo of Greenhouse Environment Control Technology based on economic optimum as claimed in claim 1, it is characterized in that: the method for the differential temperature round the clock control after improving is adopted in the environment control at greenhouse night, being about to the time period at night is divided into the first half of the night and two parts after midnight, the environment in greenhouse was controlled at the average control effect level on a little higher than daytime and deducted on the level of a differential temperature value (being generally 4-8 ℃) first half of the night, then was after midnight to add that by the low limiting temperature of crop a setting value (generally should 〉=1-2 ℃) controls.

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