CN108490988A - A kind of flow control system pump operation section method of discrimination - Google Patents
A kind of flow control system pump operation section method of discrimination Download PDFInfo
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D7/00—Control of flow
- G05D7/06—Control of flow characterised by the use of electric means
- G05D7/0617—Control of flow characterised by the use of electric means specially adapted for fluid materials
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D7/00—Control of flow
- G05D7/06—Control of flow characterised by the use of electric means
- G05D7/0617—Control of flow characterised by the use of electric means specially adapted for fluid materials
- G05D7/0629—Control of flow characterised by the use of electric means specially adapted for fluid materials characterised by the type of regulator means
- G05D7/0676—Control of flow characterised by the use of electric means specially adapted for fluid materials characterised by the type of regulator means by action on flow sources
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Abstract
The present invention provides a kind of flow control system pump operation section method of discrimination.First, small signal disturbance Δ F is applied to pump operation frequency at the flow control system arbitrary Relative steady-state moment, obtains corresponding flow volume change values Δ q1(t) with the relational expression of Relative steady-state pressure value P, and then using Gray system calculate the flow control system arbitrary Relative steady-state moment pressure value P；Secondly, it according to the Q H heat-capacity curves that calculated pressure P, the flow Q measured and frequency are F pumps, obtains pumping in the characteristic operating points Q H；Finally, Effec-tive Function region is surrounded with similar operating condition parabolic according to the Q H lift characteristics of pump, it is accurate to the traffic coverage of pump, reliable to differentiate.The differentiation that pump operation section can be realized without press detection sensor and auxiliary circuit in the present invention eliminates the installation and debugging required time and cost of pressure sensor and additional processing circuitry so that system structure is simpler, and system cost is lower.
Description
Technical field
The invention belongs to process control fields, and in particular to a kind of flow control system pump operation section method of discrimination is used
In accurate, quick discrimination pump whether in high efficiency range operation.
Background technology
Flow-rate adjustment control has a wide range of applications in fields such as chemical industry, food, medicine, water supply.Early stage flow-rate adjustment master
To be opened by the aperture of adjusting control valve and output flow be adjusted, but there are high energy consumption, adjustable range is little the deficiencies of.
The current main scheme using frequency control realizes the adjusting of output flow, and principle is mainly by detecting output flow and setting
Deviation between flow, and feedback compensation control algorithm is carried out to the deviation, and then the output frequency of frequency converter is adjusted, change pump
Rotating speed, realize the stability contorting of output flow.However, delivered in control theory and application periodical by Zhang Chenghui etc.《Become
Frequency modulation speed water supply pump station efficiency-optimized control strategy》One text is it is found that pump there are one by heat-capacity curve, similar operating condition parabolic
The Effec-tive Function section of line composition.Pump operation can realize Effec-tive Function in this section；Otherwise, the way and service life will be big
It is big to reduce.On the one hand, in chemical industry, food, the fields such as medicine, water supply can since the liquid of conveying is run in the duct for a long time
Can there can be dirt deposition, entire pipeline effective sectional area is caused to become smaller, pipe resistance characteristic is deteriorated, in the case where setting traffic conditions, pump
Outlet and ductwork pressure increased dramatically, and pump operation state is caused to change, and deviate high efficiency range；On the other hand, pump long-time
In non-efficient section, operation can cause the efficiency of frequency conversion flow control system to reduce, even result in the overload of frequency converter and pump/
Low-frequency operation increases the failure risk of frequency conversion flow control system.Effec-tive Function in order to ensure pump and strick precaution frequency converter event
Hinder risk, must just obtain the status datas such as the rotating speed, flow and lift (or pressure) of pump, determines if to be in high efficiency range
Operation.Due to using frequency control, so can be obtained the rotating speed of pump by obtaining the running frequency of pump.Thus, it is only necessary to it obtains
Running frequency, output flow and lift (or pressure) that flow control system pumps is taken to can determine the operating status of pump.Existing side
Case is increase pressure sensor at pump discharge or at pipe network key node, for detecting the pressure in pipe network in real time, in turn
The Q-H heat-capacity curves operating point pumped, to differentiate whether pump runs on high efficiency range.But the program increases due to needing
Pressurize force detection sensor, on the one hand increases the complexity and hardware cost of pipe network, another aspect frequency conversion flow control system
It needs to increase corresponding function module, such as signal conditioning circuit, sample circuit, software handler etc. in terms of software and hardware.
Invention content
It is an object of the present invention to overcome the above deficiencies, proposes a kind of flow control simple in structure, applicability is good
Systems pumps traffic coverage method of discrimination.
The present invention provides a kind of flow control system pump operation section method of discrimination, and its step are as follows：
1) pressure value P of the flow control system in stable state and t ∈ [0, T are establishedd] changes in flow rate amount Δ q1(t) pass
It is formula：Wherein；P is ductwork pressure value, and F is frequency converter output frequency, and Q is liquid in-out
Body flow, T are environment temperature, TbFor air pressure tank rated temperature, VbFor air pressure tank gas chamber nominal volume, PbFor the specified pressure of air pressure tank
Power, t are time variable, TdFor pre-defined observation interval, Δ F is frequency disturbance increment；
2) with sampling period TsThe flow value of flow control system and the output frequency of frequency converter are sampled for interval,
And flow value q (k) and output frequency f (k) are obtained, wherein k is sampling number；
3) and according to the flow value q (k) and output frequency f (k) sampled, the flow value number being made of N number of element is established
Group { q (i) } and frequency converter output frequency array { f (i) }, wherein i=k-N+1, k-N+2 ... and k }, N is to preset
Be more than 1 positive integer, q (i) |＜=0 i=0, f (i) |＜=0 i=0；
4) average value of flow value array { q (i) } is obtainedAnd it therefrom obtainsAnd judge whether to meet：σq≤εq, to identify whether flow control system is in stable state,
Wherein：εqTo set positive value；
5) when determining that the flow control system is in stable state, then the average value of frequency converter output frequency array is obtained
6) it and will identify for the first time at the time of flow control system is in stable state as the t=0 moment, and to output frequency
One fixed disturbance quantity Δ F, f (mT is provideds)=F+ Δs F, m are the number in period；
7) m ＞ M are judged, when its is invalid, then in t=mTsMoment, sample streams magnitude q (m) obtain changes in flow rate amount
Δ q (m)=q (m)-Q；If so, then enable k=k+1, continuation sample next time；
8) judgeWhen its is invalid, then by estimated pressure Pg[m] and Q, F, Δ F, Pb、Vb, T and
T=mTsSubstitute into the relational expression established in step 1And obtain the corresponding moment
Changes in flow rate amount estimated value Δ qg(m), wherein m=1,2 ..., M,TdFor pre-defined observation interval；Its
Middle Pg[1]=P1 g, wherein P1 gInitial value for the estimated pressure arbitrarily set；
9) pass through the changes in flow rate amount Δ q (m) of acquisition and changes in flow rate amount estimated value Δ q againg(m), it obtains between the two
Error sequence Δ0(m)=| Δ q (m)-Δs qg(m) |, obtain Δ q (m), Δ qg(m) related coefficient ξ (m)：Resolution ratio γ=0.5；Wherein：Δ (min)=0；Δ (max)=1；
10) and according to Δ q (m), the Δ q obtained in step 9)g(m) related coefficient ξ (m), and judge ξ (m) ＞=
Whether 0.97 is true；
11) if step 10) is set up, it is determined that estimated value Pg[m] is the practical pressure of flow control system
Force value, i.e. P=Pg[m] is system pressure value, if step 10) is invalid, more new variables：M=m+1；And it enters step again 7)；
12) the Q-H lift characteristics according to the operation data (Q, P) of pump and pump have translation feature, show that frequency is the pump of F
Q-H heat-capacity curves HF；
13) judge HFOn operating point r (Q, P) whether in the efficient region ABCD, if in efficient region ABCD,
Then obtain curve HFWith similar operating condition parabola li1、li2Intersection point a, b and its corresponding flow Qmin、QmaxIf being not at efficiently
In the ABCD of region, then k=k+1 is updated；It is sampled next time, and marks the sampling of output flow value and frequency converter output frequency
Value is q (k) and f (k), then repeatedly above step；
14) judge min { Q-Qmin,Qmax-Q}≥λ(Qmax-Qmin) whether true, if so, then determine flow control system
Pump is in efficient operation, if not, then update k=k+1；It is sampled next time, and marks output flow value and change
The sampled value of frequency device output frequency is q (k) and f (k), repeats above step.
Include the following steps in step 1)：
1. establishing flow control system water pump output power equation：
Wherein：ρ×q1(t) × p (t) is the shaft power of pump, and η is the efficiency of pump, i.e. motor effective power and axis output work
The ratio between rate, s are revolutional slip, R1,R2,X1σ,X2σ,m1,For the intrinsic parameter of pump motor,For
The output power of motor；
2. carrying out small signal disturbance to the equation of step 1., obtains relational expression and be reduced to
QΔp(t)+PΔq1(t)+Δq1(t) Δ p (t)=k'(2F Δ F+ Δs F2), wherein：q1(t)=Q+ Δs q1(t), f
(t)=F+ Δs F, p (t)=P+ Δ p (t), k'=η k/ ρ,
3. in t ∈ [0, Td] obtain system small-signal model equation：
4. obtaining in t ∈ [0, Td], the volume change of air pressure tank liquid chamber；
And thus obtain t ∈ [0, Td] when liquid chamber volume
Chamber volumeAnd it is obtained according to equation for ideal gases
The air chamber pressure variable quantity of air pressure tankAnd thus obtain ductwork pressure variable quantityDetermine pa(0)=P, then obtain
5. 3. 4. being obtained with step according to stepAnd it finally obtains
The average value of flow value array { q (i) } is obtained in step 4)And it solvesJudge whether to meet：σq≤εq, wherein：εqTo set positive value, if it meets, then it is assumed that flow
Control system is in stable state.
The efficient region ABCD is rated frequency fNHeat-capacity curve HN, low-limit frequency fminLift characteristic it is bent
Line Hmin, similar operating condition parabola li1, similar operating condition parabola li2The fan annular region surrounded.
The present invention has the advantages that：
One, pressure on-line checking can be realized without press detection sensor and auxiliary circuit in the present invention, and then obtains in real time
The status informations such as the running frequency F, flow Q and pressure P of pump are taken, the Q-H heat-capacity curves operating point of pump is determined, eliminates pressure
The installation and debugging required time and cost of force snesor and additional processing circuitry so that system structure is simpler, system cost
It is lower；
Two, the present invention is thrown in real-time acquisition pump Q-H heat-capacity curves operating point and pump Q-H lift characteristics and similar operating condition
Object surrounds on Effec-tive Function region base, accurate to the traffic coverage of pump, reliable to differentiate, foundation is provided for the efficient control of pump；
Three, flow control system pump operation of the present invention section method of discrimination has method simple, and reliability is high, real
The features such as strong with property, the safe efficient operation to be pumped in flow system provide reliable guarantee.
Description of the drawings
Fig. 1 is the structure diagram of flow control system；
Fig. 2 is flow control system lift-pipe resistance characteristic figure.
Fig. 3 is governor impeller Effec-tive Function area schematic diagram.
Fig. 4 is pump operation interval diagram
Specific implementation mode
Embodiments of the present invention is further illustrated below in conjunction with the accompanying drawings：
The present invention provides a kind of flow control system pump operation section method of discrimination, mainly establish flow control system
Mathematical model, and mathematical model according to foundation and Q-H lift characteristics and similar operating condition parabolic surround Effec-tive Function region to
Pump operation section method of discrimination is gone out.Flow control system mathematical model to establish process as follows：
Flow control system schematic diagram is as shown in Figure 1, include mainly fluid supply, check valve 2, pump M, flow detector 3, gas
Press tank 4, controller 5 and frequency converter 6 etc..Fluid supply be mainly need carry out flow control liquid medium, can be water, oil or
Other liquid；2 major function of check valve is to prevent liquid from flowing backwards；M is pumped by impeller blade high speed rotation by the liquid in fluid supply
It is transported to pipeline；Flow detector 3 is for detecting rate of discharge；Air pressure tank 4 is mainly the function of stablizing ductwork pressure；Control
Device 5 processed mainly realizes input, the display of operating status and the operation of system control program of relevant parameter；Frequency converter 6 is mainly logical
It crosses and receives the controlled quentity controlled variable that controller is sent out, adjust revolution speed, realize pump output flow control.
Variable declaration is as follows：q1(t) it is pump discharge flow；q2(t) it is air pressure tank rate of discharge；P (t) is the pressure of pipe network
Value；F (t) is frequency converter output frequency；Air pressure tank chamber volume is v1(t)；Air pressure tank air chamber pressure pa(t), air pressure tank liquid chamber body
Product is v2(t), air pressure tank sectional area is S, and air pressure tank total volume is Vz, air pressure tank rated pressure value Pb, the specified body of air pressure tank gas chamber
Product Vb, air pressure tank rated temperature Tb, environment temperature is T (t), and t is time variable, and ρ is fluid density, and g is acceleration of gravity.
When flow control system Relative steady-state：Ductwork pressure value is P, and frequency converter output frequency is F, passes in and out fluid flow
For Q, environment temperature T, air pressure tank chamber volume is V1, liquid chamber volume is V2, the unit of above-mentioned all amounts is international unit.
Define the t=0 moment be system with the last moment of frequency F stable operations, that is, exist：
Assuming that [0, Td] running frequency that pumps in the time is：F (t)=F+ Δ F, Δ F is frequency disturbance increment, usual feelings
Under condition | Δ F | ＜ ＜ F；TdFor pre-defined observation interval, for the time value more than 0, according to flow control system
Energy index is different and artificially determines；Then pressure value is p (t)=P+ Δ p (t), and Δ p (t) is pressure oscillation value caused by Δ F；Pump
Rate of discharge is q1(t)=Q+ Δs q1(t), Δ q1(t) it is pump discharge flow undulating value caused by Δ F；Air pressure tank rate of discharge
For q2(t)=Q+ Δs q2(t), Δ q2(t) it is air pressure tank rate of discharge undulating value caused by Δ F；By motor frequency conversion control it is found that
The relationship of the output power of pump is：
Wherein：ρ × the q on the equation left side1(t) × p (t) is the shaft power of pump；η is the efficiency of pump；For the output power of motor；S is revolutional slip； R1,R2,X1σ,X2σ,m1,For pump motor
Intrinsic parameter；
Since pump motor uses variable frequency regulating speed control, so s is held essentially constant.It enables：
K is only related with motor structural parameters itself, unrelated with flow, pressure.So formula (1) can be reduced to：
q1(t) p (t)=k η f (t)2/ρ (3)
Enable k'=η k/ ρ.Then in t=0, have：
QP=k'F2 (4)
In t ∈ [0, Td], by q1(t)=Q+ Δs q1(t), f (t)=F+ Δs F and p (t)=P+ Δ p (t) substitute into formula (4)：
(Q+Δq1(t)) (P+ Δ p (t))=k'(F+ Δ F)2 (5)
It is unfolded (5), and arranges：
PQ+QΔp(t)+PΔq1(t)+Δq1(t) Δ p (t)=k'(F2+2FΔF+ΔF2) (6)
(4) substitution (6) can be obtained：
QΔp(t)+PΔq1(t)+Δq1(t) Δ p (t)=k'(2F Δ F+ Δs F2) (7)
Since there are the big inertia damping links of air pressure tank, then in t ∈ [0, Td] changes in flow rate amount Δ q in the short time1(t) draw
Pressure variety Δ p (t) very littles risen meet：
| Δ p (t) | ＜ ＜ P (8)
It is obtained so arranging (7)：
QΔp(t)+PΔq1(t)=k'(2F Δ F+ Δs F2) (9)
By formula (9) divided by (4) and consider | Δ F | ＜ ＜ F can be obtained：
Due in t ∈ [0, Td] have | Δ p (t) | ＜ ＜ P, i.e. ductwork pressure are kept approximately constant, and are not had in pipe resistance characteristic
In the case of change, the rate of discharge variation delta q of air pressure tank2(t) 0 ≈, i.e. q2(t)≈Q.Have according to air pressure tank kinetics equation：
In t ∈ [0, Td], the volume change of air pressure tank liquid chamber is：
So t ∈ [0, Td] liquid chamber volume is：
Because V is remained unchanged, thus chamber volume is：
In t ∈ [0, Td] in the time, environment temperature remains unchanged, then from equation for ideal gases：
(13) are substituted into (14) and are arranged：
Enable Δ pa(t)=pa(t)-pa(0) it is air pressure tank air chamber pressure variable quantity, then：
According to hydraulic principle it is found that ductwork pressure variable quantity is：
By pa(0)=P substitutes into formula (17), can obtain：
Simultaneous (18) and (10) simultaneously arrange：
It enables：Then have：Y'(t)=Δ q1(t), thus have：Y (0)=y'(0)=0, to formula
(19) arranging can obtain：
The differential equation (20) is arranged and considers that Δ F ＜ ＜ F, 2 × Δ F ＜ ＜ F can be obtained：
Solving (21) can obtain：
It willIt substitutes into formula (22) and arranges：
In t ∈ [0, Td], due to | Δ F | ＜ ＜ F and | Δ p (t) | ＜ ＜ P, according to (5) it is found that Δ q1(t) ＜ ＜ Q, institute
To have：
Below for Δ F withSyntactics discuss analysis：As Δ F ＞ 0, due to f
(t)=F+ Δ F ＞ F, thus q1(t)=Q+ Δs q1(t) ＞ Q, so there is Δ q1(t) 0 ＞；Similarly, as Δ F ＜ 0, due to f
(t)=F+ Δ F ＜ F, thus q1(t)=Q+ Δs q1(t) ＜ Q, so there is Δ q1(t) 0 ＜；So：Δ F and Δ q1(t) jack per line,
That is, Δ F and y (t) jack per lines.So having：
Again due in t ∈ [0, Td], the right end of formula (24) meets：Qt ＞ 0, so having：
So formula (24) can arrange：
(27) are solved equation to obtain：
Again because of Δ q1(t)=y'(t), so having：
Because of air pressure tank No leakage, then from equation for ideal gases：
Simultaneous formula (29) and (30), and arrange：
Due to t ∈ [0, Td], if to TdSelection meets inequality：
Then (31) are carried out Taylor series expansion and arranged to obtain：
Due toSo expression formula (33) can be approximately：
Due to parameter, Δ q1(t), Q, F, Δ F, Pb、Vb、Tb, T and t be observable quantity and known quantity, thus pass through acquisition
Changes in flow rate amount Δ q1(t) value can values of pressure p of the on-line measurement outflow control system in stable state size.
The pressure P at flow control system arbitrary Relative steady-state moment can be found out according to formula (34).At the same time, flow control
The value of the running frequency F of system output stream magnitude Q and pump processed can be obtained by the output frequency of flow sensor and reading frequency converter
, and then flow control system pump is got in the characteristic operating points Q-H.
Fig. 3 show governor impeller Effec-tive Function area schematic diagram, and the Effec-tive Function section of pump is rated frequency fNLift it is special
Linearity curve HN, low-limit frequency fminHeat-capacity curve Hmin, similar operating condition parabola li1, similar operating condition parabola li2It surrounds
Fan annular region ABCD.If pump is in region ABCD in the characteristic operating points Q-H, pump is in Effec-tive Function；Conversely,
Pump is in non-efficient operating status.
Since flow control system realizes flow-rate adjustment control mode, thus different running frequency situations using frequency control
The heat-capacity curve of lower pump has translation feature.Pump operation section distribution situation is described in detail with reference to Fig. 3.
(1) flow control system output flow is Q1：
Assuming that when the running frequency of front pump is f1, then the heat-capacity curve pumped is H1, flow Q1Corresponding operating point
Pressure value be P1.From the figure 3, it may be seen that when front pump is in efficient region ABCD.If certain moment flow control system is because of other
When factor causes pressure to reduce (for example, fluid pipeline change causes pipe resistance to reduce, and liquid enters reaction groove tank of low lift etc.),
Then maintaining output flow Q1In the case of constant, the running frequency of pump must be reduced, it is assumed that the running frequency of pump is at this time
f2, heat-capacity curve is switched to H2.From the figure 3, it may be seen that characteristic curve H2Middle flow is Q1The pressure value of corresponding operating point is
P2, at this time pump operation point be not in efficient region ABCD, the inefficiency of pump, fever is serious.
(2) flow control system output flow is by Q1It is adjusted to Q2
Assuming that when the running frequency of front pump is f1, then the heat-capacity curve pumped is H1, flow Q1Corresponding operating point
Pressure value be P1.If certain moment flow control system setting output flow increases to Q2, then not due to the pipe resistance characteristic of system
Become, increasing output flow necessarily causes pipe resistance to increase, and must improve the running frequency of pump, it is assumed that the running frequency of pump is at this time
f3, heat-capacity curve is switched to H3.From the figure 3, it may be seen that characteristic curve H3Middle flow is Q2The pressure value of corresponding operating point is
P3, at this time pump operation point be not in efficient region ABCD, the inefficiency of pump, fever is serious.
By above-mentioned analysis it is found that the traffic coverage of flow control system pump is not to be constantly in high efficient district, with
Output flow and system pipes resistance variation and change, in order to realize efficient, the safe and reliable operation of flow control system, then must
The traffic coverage of pump need be differentiated.
The present invention provides a kind of flow control system pump operation section method of discrimination, include the following steps：
(1) with sampling period TsFlow control system flow value and frequency converter output frequency are sampled for interval, it will
First time sampled value is labeled as q (1) and f (1)；Present sample number is k, enables k=1；
(2) the flow value array { q (i) } being made of N number of element and frequency converter output frequency array { f (i) } are established,
Wherein i={ k-N+1, k-N+2 ... k }, N be it is preset be more than 1 positive integer, k is present sample number；q(i)
|＜=0 i=0, f (i) |＜=0 i=0；
(3) judge whether flow control system is in metastable state, the definition of metastable state is：Calculate { q
(i) } average valueAnd it solvesJudge whether to meet：σq≤εq,
In：εqTo set positive value, can be set according to real system, for example 0.05 or 0.1 can be taken.If it is satisfied, then thinking
Flow control system is in metastable state, enters step (4)；Otherwise, flow control system plays pendulum, and is transferred to
Step (16)；
(4) average value of frequency converter output frequency is solved
(5) t=0 is denoted as with blaze at this time, gives output frequency one smaller disturbance quantity Δ F, i.e. f (mTs)=F+ Δs F；
(6) P is definedg[m] is t=mTsThe estimated pressure at moment defines Δ qg(m) it is that corresponding moment changes in flow rate amount is estimated
Evaluation；Wherein m=1,2 ..., M,TdFor pre-defined observation interval；Enable Pg[1]=P1 g, wherein P1 gFor
The initial value of the estimated pressure arbitrarily set；
Enable m=1, second level lowest difference Δ (min)=0, the maximum poor Δ (max)=1 in the second level, resolution ratio γ=0.5；
(7) judge whether m ＞ M are true, if set up, enter step (16)；Otherwise, in t=mTsMoment, sample streams
Magnitude is denoted as q (m)；Obtain Δ q (m)=q (m)-Q；
(8) judgeWhether it is true (α is artificial arbitrary setting value, but 0.01,0.05 or other are small
Number).If invalid, it is transferred to step (16)；Otherwise, by estimated pressure Pg[m] and Q, F, Δ F, Pb、Vb, T and t=mTs
Substitute into formula：Solution obtains Δ qg(m)。
(10) judge whether ＞=0.97 ξ (m) true (ξ (m) is related coefficient, i.e. actual flow changing value Δ q (m) and
Estimated flow changing value Δ qg(m) degree of closeness, related coefficient ξ (m) is bigger, shows Δ qg(m) closer with Δ q (m), work as ξ
(m)=1 when, Δ q (m) and Δ qg(m) completely the same).It sets up, enters step (11)；Otherwise, more new variables：M=m+1；
Return to step (7).
(11) estimated value Pg[m] is exactly flow control system actual pressure value, i.e. P=Pg[m] is system pressure value.
(12) the Q-H lift characteristics according to the operation data (Q, P) of pump and pump have translation feature, show that frequency is F's
The Q-H heat-capacity curves of pump, are denoted as HF。
(13) judge HFOn operating point r (Q, P) whether in the efficient region ABCD.It sets up, then enters step (14)；
Otherwise, it enters step (16).
(14) calculated curve HFWith similar operating condition parabola li1、li2Intersection point, be denoted as point a, b and its corresponding flow
Qmin、Qmax。
(15) judge min { Q-Qmin,Qmax-Q}≥λ(Qmax-Qmin) whether it is true (wherein：λ is between 0 to 0.5
Number differentiates that reliability performance determines by Effec-tive Function section).It sets up, then illustrates that flow control system pump is in Effec-tive Function, and
It enters step (16)；Otherwise, it enters step (16).
(16) k=k+1 is enabled；It is sampled next time, and marks the sampled value of output flow value and frequency converter output frequency
For q (k) and f (k)；Return to step (2).
Embodiment is not construed as limitation of the present invention, any spiritual improvements introduced based on the present invention, all Ying Ben
Within the protection domain of invention.
Claims (4)
1. a kind of flow control system pump operation section method of discrimination, it is characterised in that：Its step are as follows：
1) pressure value P of the flow control system in stable state and t ∈ [0, T are establishedd] changes in flow rate amount Δ q1(t) relational expression：Wherein；P is ductwork pressure value, and F is frequency converter output frequency, and Q is disengaging liquid flow
Amount, T is environment temperature, TbFor air pressure tank rated temperature, VbFor air pressure tank gas chamber nominal volume, PbFor air pressure tank rated pressure, t
For time variable, TdFor pre-defined observation interval, Δ F is frequency disturbance increment；
2) with sampling period TsThe flow value of flow control system and the output frequency of frequency converter are sampled for interval, and obtained
It is sampling number to take flow value q (k) and output frequency f (k), wherein k；
3) and according to the flow value q (k) and output frequency f (k) sampled, the flow value array { q being made of N number of element is established
(i) } and frequency converter output frequency array { f (i) }, wherein i={ k-N+1, k-N+2 ... k }, N is preset is more than
1 positive integer, q (i)＜=0 i=0, f (i)＜=0 i=0；
4) average value of flow value array { q (i) } is obtainedAnd it therefrom obtainsAnd judge whether to meet：σq≤εq, to identify whether flow control system is in stable state,
Wherein：εqTo set positive value；
5) when determining that the flow control system is in stable state, then the average value of frequency converter output frequency array is obtained
6) it and will identify for the first time at the time of flow control system is in stable state as the t=0 moment, and output frequency will be provided
One fixed disturbance quantity Δ F, f (mTs)=F+ Δs F, m are the number in period；
7) m ＞ M are judged, when its is invalid, then in t=mTsMoment, sample streams magnitude q (m) obtain changes in flow rate amount Δ q (m)
=q (m)-Q；If so, then enable k=k+1, continuation sample next time；
8) judgeWhen its is invalid, then by estimated pressure Pg[m] and Q, F, Δ F, Pb、Vb, T and t=mTs
Substitute into the relational expression established in step 1And it obtains corresponding moment flow and becomes
Change amount estimated value Δ qg(m), wherein m=1,2 ..., M,TdFor pre-defined observation interval；Wherein Pg
[1]=P1 g, wherein P1 gInitial value for the estimated pressure arbitrarily set；
9) pass through the changes in flow rate amount Δ q (m) of acquisition and changes in flow rate amount estimated value Δ q againg(m), error between the two is obtained
Sequence Δ0(m)=| Δ q (m)-Δs qg(m) |, obtain Δ q (m), Δ qg(m) related coefficient ξ (m)：Resolution ratio γ=0.5；Wherein：Δ (min)=0；Δ (max)=1；
10) and according to Δ q (m), the Δ q obtained in step 9)g(m) related coefficient ξ (m), and whether judge ＞=0.97 ξ (m)
It sets up；
11) if step 10) is set up, it is determined that estimated value Pg[m] is the actual pressure value of flow control system, i.e. P=Pg[m] is
System pressure value, if step 10) is invalid, more new variables：M=m+1；And it enters step again 7)；
12) the Q-H lift characteristics according to the operation data (Q, P) of pump and pump have translation feature, show that frequency is the Q- of the pump of F
H heat-capacity curves HF；
13) judge HFOn operating point r (Q, P) whether in the efficient region ABCD, if in efficient region ABCD, obtain
Take curve HFWith similar operating condition parabola li1、li2Intersection point a, b and its corresponding flow Qmin、QmaxIf being not at efficient region
In ABCD, then k=k+1 is updated；It is sampled next time, and marks the output flow value and the sampled value of frequency converter output frequency to be
Q (k) and f (k), then repeatedly above step；
14) judge min { Q-Qmin,Qmax-Q}≥λ(Qmax-Qmin) whether true, if so, then determine at flow control system pump
In efficient operation, if not, then update k=k+1；It is sampled next time, and marks output flow value and frequency converter
The sampled value of output frequency is q (k) and f (k), repeats above step.
2. a kind of flow control system pump operation section according to claim 1 method of discrimination, it is characterised in that：Step 1)
In include the following steps：
1. establishing flow control system water pump output power equation：
Wherein：ρ×q1(t) × p (t) is the shaft power of pump, and η be the efficiency of pump, i.e., motor effective power and shaft power it
Than s is revolutional slip, R1,R2,X1σ,X2σ,m1,For the intrinsic parameter of pump motor,For motor
Output power；
2. carrying out small signal disturbance to the equation of step 1., obtains relational expression and be reduced to
QΔp(t)+PΔq1(t)+Δq1(t) Δ p (t)=k'(2F Δ F+ Δs F2), wherein：q1(t)=Q+ Δs q1(t),
F (t)=F+ Δs F, p (t)=P+ Δ p (t), k'=η k/ ρ,
3. in t ∈ [0, Td] obtain system small-signal model equation：
4. obtaining in t ∈ [0, Td], the volume change of air pressure tank liquid chamber；
And thus obtain t ∈ [0, Td] when liquid chamber volume
Chamber volumeAnd air pressure is obtained according to equation for ideal gases
The air chamber pressure variable quantity of tankAnd thus obtain ductwork pressure variable quantityDetermine pa(0)=P, then obtain
5. 3. 4. being obtained with step according to stepAnd it finally obtains
3. a kind of flow control system pump operation section according to claim 1 method of discrimination, which is characterized in that step 4)
The middle average value for obtaining flow value array { q (i) }And it solvesJudgement is
No satisfaction：σq≤εq, wherein：εqTo set positive value, if it meets, then it is assumed that flow control system is in stable state.
4. a kind of flow control system pump operation section according to claim 1 method of discrimination, which is characterized in that the height
Effect region ABCD is rated frequency fNHeat-capacity curve HN, low-limit frequency fminHeat-capacity curve Hmin, similar operating condition throw
Object line li1, similar operating condition parabola li2The fan annular region surrounded.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110954172A (en) * | 2019-12-03 | 2020-04-03 | 温州大学 | Flow detection method for parallel variable-frequency constant-pressure water supply system |
| CN111190442A (en) * | 2020-01-02 | 2020-05-22 | 温州大学 | Newton iteration-based parallel variable-frequency constant-voltage control system operation interval discrimination method |
| CN111190443A (en) * | 2020-01-02 | 2020-05-22 | 温州大学 | Control method of parallel variable-frequency constant-voltage control system based on Newton iteration |
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2018
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110954172A (en) * | 2019-12-03 | 2020-04-03 | 温州大学 | Flow detection method for parallel variable-frequency constant-pressure water supply system |
| CN111190442A (en) * | 2020-01-02 | 2020-05-22 | 温州大学 | Newton iteration-based parallel variable-frequency constant-voltage control system operation interval discrimination method |
| CN111190443A (en) * | 2020-01-02 | 2020-05-22 | 温州大学 | Control method of parallel variable-frequency constant-voltage control system based on Newton iteration |
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