A kind of Trans-critical cycle CO based on GMDH algorithm2System optimal pressure at expulsion characteristic variable
Determine method
Technical field
The invention belongs to technical field of heat pumps, in particular to a kind of CO2The determination of the optimal pressure at expulsion characteristic variable of heat pump
Method.
Background technique
With the further development of economic society, the common pass of environmental protection and sustainable development as whole mankind society
It cuts.The signing of Montreal Agreement indicates that influence problem of the refrigerant for environment obtains weight in the world for the first time
Depending on the substitution of refrigerant also becomes the first element of guidance refrigerating and air conditioning industry development since then.In grinding for novel synthesis refrigerant
The novel environment friendly and refrigeration problem occurred in hair and extension process allows more and more researchers to firmly believe that natural refrigerant will
The terminal of this wheel substitution can be become.In natural refrigerant, carbon dioxide by its own excellent thermophysical property and across
The popularization of critical assembly becomes the research hotspot of heat pump industry instantly.
In Trans-critical cycle CO2In the research of heat pump water heater system, the research of system optimal pressure at expulsion is that its is most crucial
One of content, and wherein determining which parameter has specific influence and corresponding parameter to optimal row system optimal pressure at expulsion
Atmospheric pressure effect is the basis that system optimal pressure at expulsion controls under the conditions of realizing variable working condition.Numerous scholars are herein
Significant contribution is made in field, and proposes Trans-critical cycle CO2The optimal pressure at expulsion correlation of heat pump system.In Trans-critical cycle CO2
In the development process of heat pump system unit, also mode controls after system unit selects to complete in design researcher like this
The calculation formula conduct for the optimal pressure at expulsion being fitted by lot of experimental data is typically chosen when system.But a large amount of experiment
What the calculation formula of data fitting was most adapted to is the optimal pressure at expulsion of experimental prototype system, in actual engineering background, i.e.,
Make to carry out assembling production using identical accessory, it is also possible to which, because of mounting process, the performance difference of different batches of product makes
The performance difference that shows of final unit is very big, this just brings following problems to the exploitation of unit control system:
(1) go control unit that cannot be adapted to external work condition environment completely by the conventional optimal control algorithm to model machine.
(2) there are biggish deviations when going prediction optimum pressure based on existing empirical equation, and over time
The performance degradation of unit will increase such otherness.
In order to realize control system accurately controlling for optimal pressure at expulsion, the efficiency based on Real-time data drive is used
Decision carries out characteristic of division extraction to the variable for influencing system optimal pressure at expulsion and Effectiveness Forecast is necessary.
Summary of the invention
The purpose of the present invention is to provide a kind of Trans-critical cycle CO based on GMDH algorithm2System optimal pressure at expulsion feature becomes
Method for determination of amount, to solve the above technical problems.
To achieve the goals above, the present invention adopts the following technical scheme:
A kind of Trans-critical cycle CO based on GMDH algorithm2The determination method of system optimal pressure at expulsion characteristic variable, including with
Lower step:
Step 1: acquisition Trans-critical cycle CO2Sample obtained in heat pump water heater system working condition measurement process obtains sample number
According to collection;Construct Effectiveness Forecast model, input for environment temperature, evaporator outlet temperature, suction temperature, delivery temperature, water pump into
Coolant-temperature gage, water pump water outlet temperature, air cooling outlet temperature, evaporator coil temperature and pressure of inspiration(Pi), export as pressure at expulsion;
Set of data samples is divided, training set is indicated with alphabetical A, for generating competitive model;It indicates to examine with letter b
Test collection;There is w using outer criterion to screen competitive modeln=NA+NB, w=A ∪ B, wherein w indicates all data samples;
Step 2: determining reference function for the single output sample data set of 9 inputs determined in the first step
For the mapping relations of independent variable and dependent variable, and with its subitem v1=a0, v2=a1x1, v3=a2x2... .., v55=a54x8x9
As 55 initial models in modeled network;
Step 3: determining the calculation formula of outer criterion are as follows: Y in formulatFor t-th of real output value;T-th of the output for the model estimation obtained on data set K
Value, K takes A, B and A ∪ B=w in modeling;
Step 4: building binary linearity function y=axi+bxjMid-module is generated as transmission function and is carried out layer-by-layer
Screening, ultimately forms optimal complexity model structure.
The correlated variables of optimal pressure at expulsion has 9, and GMDH algorithm purpose is the method pair selected using hereditary variation
This 9 variables are evaluated, and determine the most correlated variables in final optimal pressure at expulsion correlation.The purpose of the transmission function
It is to generate mid-module, heredity and variation is carried out to upper one layer of model.Specific practice are as follows: upset training set, detection in advance
Collect sample order, which is carried out 50 times at random, and during carrying out each time, carries out GMDH, obtain optimal complexity
Model counts probability of the every kind of element as main composition;Random 50 experimental results are counted for each experiment, and are taken
The average values for obtaining 50 tests, thus according to the sequence for obtaining most correlated variables from big to small of probability of occurrence.
Further, in the 4th step, transmission function wk=axi+bxjFor first layer mid-module, wherein competitive model number
The size of k is related with the item number m of preceding layer, m=9, then obtains according to formulaIt indicates in first layer by self-organizing
Process adaptive generates 36 competitive models, and different due to contained variable number, the otherness of function structure each other;Exist simultaneously
W is estimated on training set AkParameter a, b;
Mid-module builds the competitive model of the second layer in turn in first layer mid-module ground foundation;The input of the second layer
The output variable w of variable and first layerkEqual, the number for constructing competitive model isCollect B again by detection
Second layer mid-module is screened, the competitive model chosen enters third layer;
It is true by outer criterion in the identical pattern number of structure that the second selection layer generation enters next layer since the second layer
It is fixed;By constantly generating competitive model and being screened according to outer criterion value, the complexity of model is continuously increased, while passing through meter
It calculates outer criterion value and improves model quality;When model quality can not improve again, modeling process stops, and optimal models are found;This
When detection collection on the minimum fitting variance that calculatesObtain global minimum.
Further, circulation is added in GMDH algorithm, it is ensured that the different partitioning schemes of training set, inspection set, generation contain
There are more Trans-critical cycle CO2The sample combination of system variable;It is assumed that n is the total number of samples of training set, from 2 circulation values to n-
1, it is ensured that training set and completeness of the forecast set sample allocation proportion under same sample distribution sequence.
Further, for the fairness of comparative analysis, it is ensured that the completeness of sample order;Statistics is wanted as main composition
Plain frequency of occurrence upsets training set, detection collection sample order in advance, which is carried out 50 times at random, and carries out each time
In the process, GMDH is carried out, then counts probability of the every kind of element as main composition;It is counted random 50 times for each experiment
Experimental result, and obtain the average value of 50 tests.
Further, the sample that sample data is concentrated is Trans-critical cycle CO2It is recorded under heat pump water heater system COP stable state
System operation data.
Further, it is 5000 that sample data, which concentrates the quantity of sample,.
Compared with prior art, the invention has the following advantages:
The optimal control algorithm of traditional Control System Design is the optimal pressure at expulsion based on the fitting of experimental prototype data
Formula fails to consider to give Trans-critical cycle system the problems such as device aging in device otherness and operational process in Practical Project manufacture
Bring performance difference.A kind of Trans-critical cycle CO based on GMDH algorithm provided by the invention2System optimal pressure at expulsion feature becomes
Method for determination of amount is the efficiency decision based on Real-time data drive, goes to excavate Trans-critical cycle CO using the method for data mining2Heat
The characteristic variable that operation is influenced in pumping system, so that subjective experience and the judgement of researcher is overcome, independent of researcher
Experience, intuition, judged and selected by the real time data itself that system generates.
Compared with other data digging methods, GMDH algorithm has the advantages that following some:
(1) modeling process intelligence degree is high.Modeler is outside providing sample data and outer criterion, to guarantee it in mould
Objectivity in type selection, is no longer participate in remaining modeling process, to ensure that the freedom of computer software.
(2) compared with the implicit models such as ANN (neural network), SVM, grey relational grade, GMDH can obtain display expression mould
Type is conducive to the influence factor of people's identifying system.
(3) anti-interference is stronger, precision of prediction is relatively high.GMDH algorithm is using data-driven as starting point, to improve
The fitting accuracy of model guarantees that algorithm finds the model for meeting true inherent law under data noise disturbance state, passes through
Selection criterion makes the complexity that network structure is optimal.
Detailed description of the invention
In order to illustrate more clearly of a kind of Trans-critical cycle CO based on GMDH algorithm provided by the invention2System optimal exhaust pressure
The determination method of power characteristic variable below will be briefly described required attached drawing in present invention description.
Fig. 1 is the optimal pressure at expulsion characteristic variable extraction step flow chart based on GMDH algorithm;
Fig. 2 is that GMDH generates optimal models process schematic.
Specific embodiment
Refering to Figure 1, a kind of Trans-critical cycle CO based on GMDH algorithm provided by the invention2System optimal pressure at expulsion
The determination method of characteristic variable, comprising the following steps:
Step 1: determining data sample collection, to construct Effectiveness Forecast model, selection obtains during unit working condition measurement
5000 sample data sets, input for environment temperature (DEG C), evaporator outlet temperature (DEG C), suction temperature (DEG C), exhaust temperature
Spend (DEG C), water feeding of water pump temperature (DEG C), water pump water outlet temperature (DEG C), air cooling outlet temperature (DEG C), evaporator coil temperature (DEG C)
With pressure of inspiration(Pi) (MPa), export as pressure at expulsion (MPa).
The control program using optimum pressure of unit in actual operation, it is primary every acquisition in 5 minutes.Identical
The case where being tested under test condition, unit, which reaches test stable state, to be needed to undergo a period of time, this is unit operating condition in stabilization
The data recorded in the case where reaching measurement condition.Wherein, water feeding of water pump temperature and water pump water outlet temperature belong in unit data
The operation data of exterior meets physical condition by changing the frequency of water route water pump.According to actual operating condition, because
Need to do a series of working condition measurement experiments for single energization test experiments, temperature and inlet and outlet temperature have the case where variation, number
According to eliminated be not keyed up and be just switched on do not access optimum pressure operation data.Institute selectively data be
Trans-critical cycle CO under test macro2The system operation data recorded under heat pump system COP stable state, at this time inlet and outlet temperature and environment
Temperature is stationary value.
Set of data samples is divided, training set (being indicated with alphabetical A) determines model ginseng for generating competitive model
Several and structure, inspection set (being indicated with letter b) screen competitive model using outer criterion;There is wn=NA+NB, w=A ∪ B, wherein
wnIndicate all data sample numbers, NAIndicate training set number of samples, NBIndicate inspection set number of samples.
Step 2: reference when establishing self-organizing model, according to independent variable (input) and dependent variable (output) mapping relations
Function generates initial tissu (initial model set), and this kind of systems are described by self evolving for tissue.For
The system of finite memory point, reference function use Kolmogorov-Gabor (abbreviation K-G) multinomial, expression formula are as follows:
Wherein x1~xnFor relevant different variables,For the coefficient of multinomial subitem.By the multinomial
Subitem as m initial model in modeled network structure, the K-G multinomial inputted for n, in modeled network structure
Initial model m=1+2n+ (n (n-1))/2.For the single output sample data set of 9 inputs determined in the first step, reference is determined
Function For the mapping relations of independent variable and dependent variable, wherein x1~x9For environment temperature (DEG C), evaporator
Outlet temperature (DEG C), suction temperature (DEG C), delivery temperature (DEG C), water feeding of water pump temperature (DEG C), water pump water outlet temperature (DEG C), air cooling
Outlet temperature (DEG C), evaporator coil temperature (DEG C) and pressure of inspiration(Pi) (MPa), f (x1, x2.., x9) indicate as output quantity
Pressure at expulsion (MPa), a0~a54For the coefficient of multinomial subitem, by multinomial subitem v1=a0, v2=a1x1, v3=
a2x2..., v55=a54x8x9As 55 initial models in modeled network.
Step 3: constructing mid-module on training dataset in system model build process, and carries out parameter and estimate
Meter, i.e., screening process is distinguished using the quality of different competitive models.And outer criterion is exactly the number of these particular requirements
Description is learned, by calculating outer criterion value (by exporting yMWith the difference of the actual observed value of output y), from simple candidate family
" optimal " model is selected in class, then the model of " best " is obtained by the restriction of external condition.Outer criterion calculation formula are as follows: J
(C)=E { Q (yM, y, C) }, y in formulaMFor the output valve of reference function, y is actual observed value, and J (C) is outer criterion value, and C is indicated
Data set, Q indicate that loss function, E indicate desired value.
Common outer criterion includes accuracy criteria, correlation criterion, compatibility criterion, variable balance criterion etc..It is quasi- outside
Aspect is then selected, Ivakhnenko emphasizes specifically be chosen during feature extraction according to the specific features of problem,
And then improve fitting precision.During this system model buildings, in order to improve precision of prediction, the calculation formula of criteria for prediction is such as
Under:Y in formulatFor t-th of real output value;For t-th of output valve of the model estimation obtained on data set K, K takes A, B and A ∪ B=w, A in formula in modeling
Indicate that training set, B indicate that inspection set, w indicate all data samples.
Step 4: building binary linearity function y=axi+bxjMid-module is generated as transmission function and is carried out layer-by-layer
Screening, forms optimal complexity model structure, wherein xi, xjIndicate that one layer of model, y indicate this layer of newly generated centre
Model, a, b are parameter.
Further, as shown in Fig. 2, in the 4th step, transmission function wk=axi+bxjFor first layer mid-module, wherein competing
The size for striving Number of Models k is related with the item number of preceding layer, such as m=9, then can obtain according to formulaIt indicates the
One layer is adaptively generated 36 neurons (competitive model) by self-organizing process, and each other because of contained variable number, function structure
Otherness and it is different.W is estimated on training set A simultaneouslykParameter a, b.
Wherein, the partial competition model structure that first layer generates is as follows:
w1=a1x1+b1x2, w2=a2x1+b2x3... ..., w7=a7x1+b7x8, w8=a8x1+b8x9
w9=a9x2+b9x3... ..., w14=a14x2+b14x8, w15=a15x2+b15x9
……
w34=a34x7+b34x8, w35=a35x7+b35x9
w36=a36x8+b36x9
Mid-module in first layer mid-module ground foundation and then will build the competitive model of the second layer, i.e. the second layer
The output variable w of input variable and first layerkEqual, the number for constructing competitive model isAgain by inspection
It surveys collection B to screen second layer mid-module, the competitive model chosen enters third layer.
It is true by outer criterion in the identical pattern number of structure that the second selection layer generation enters next layer since the second layer
It is fixed.By constantly generating competitive model and being screened according to outer criterion value, the complexity of model is being continuously increased, and is passed through simultaneously
It calculates outer criterion value and improves model quality.When model quality can not improve again, modeling process stops, and optimal models are found.
The minimum fitting variance calculated on detection collection at this timeObtain global minimum.
Further, in order to verify the combinations of the various variables of system under various working, extracting influences most under different operating conditions
The main feature of excellent row pressure, has done circular treatment in systems.Circulation is added in GMDH algorithm, it is ensured that training set, inspection set
Different partitioning schemes, generate contain more Trans-critical cycle CO2The sample combination of system variable.In order to different Trans-critical cycles
CO2Heat pump unit carries out identification sequence, calculates its corresponding probability of happening according to feature extraction number.It is assumed that n is training set
Total number of samples can ensure that training set and forecast set sample allocation proportion in same sample distribution from 2 circulation values to n-1
Completeness under sequence.
Further, for the fairness of comparative analysis, it is ensured that the completeness of sample order.Statistics is wanted as main composition
Plain frequency of occurrence upsets training set, detection collection sample order in advance, which is carried out 50 times at random, and carries out each time
In the process, GMDH is carried out, then counts (frequency/all main composition sum of the single element as main composition) and counts every kind and want
Probability of the element as main composition.Random 50 experimental results are counted for each experiment, and obtain being averaged for 50 tests
Value.
Characteristic variable of the element stood out by selection statistical result as optimal pressure at expulsion, is subsequent optimal
The formulation of pressure at expulsion formula fitting and control strategy provides basis.By comparing final control strategy with previous by experiment number
From the point of view of effect according to control strategy made of fitting formula, GMDH method selected characteristic variable can be more objectively from data sheet
The subjective guess that body sets out and avoids researcher for Unknown Model, so that relatively good control effect is obtained, this
Outside, the adjustment of the control strategy of current database is most adapted to by can also voluntarily realize for the update of database in real time.