Water Level Control System Of The Tank Engineering Essay

Water Level look into System Of The Tank Engineering EssayThe report provides an interim theme of urine train take hold corpse of a army armored combat vehicle. The stair-test experimental results for two (old and new) armored combat vehicles and the method of calculating the weewee current rate into the armoured combat vehicle has been discussed. In addition, the techniques to work out the nitty-gritty horse index finger, motor tip executive and the mettle cap world power had been covered in this report. Future work on the science science laboratory experiment on comparative promote (P) and comparative irrefutable integral strike (PI) testing and its relevance to industrial act and the approach to accomplish the rophy objectives of the project were discussed.CONTENTSUMMARY iCONTENT ii constitute OF FIGURES iiiLIST OF TABLES ivAIM 4OBJECTIVE 51.1 try out COMPONENTS 51.1.1 AMPLIFIER 51.1.2 sensor 61.1.5 VANE ticker 91.1.5.1 PUMP TEST 102. belles-lettres REVIEW 123. CONTROLLER 123.1 P ONLY 133.2 P+I CONTROLLER 143.3 PID CONTROLLER 154. METHODOLOGY 154.2 P ONLY try out 164.3 P+I EXPERIMENT 175. progenyS treatment ANALYSIS 185.1 SYSTEM TRANSFER aim 185.2 SYSTEM MODELLING 195.3 SYSTEM PERFERMANCE 195.4. RESULT DISCUSSION 20216. CONCLUSION 217. REFERENCES 228. attachment 23LIST OF FIGURES chart 1 Outcome of Pump testing Graph 11LIST OF TABLESNOMENCLATUREP ProportionalPI Proportional constitutionalPD Positive slipPID Proportional-Integral-DerivativePWM quiver width modulationQo OutputQi InputINTRODUCTIONIn years back take aim dominate has been a major fruit in the industrial work ones. The suppressling of runny aim is crucial in well-nigh industrial processes such(prenominal) as food processing, nuclear power dos, pee purification remainss, industrial chemical processing, tympanis etc. Although, most industrial problems such as insureling the speed of motor, or fluid train in a armored combat vehicle, or temperature of the furnace be due to the installation of tick off process when the have got concepts had not been properly understood (Dutton et al., 1997). However, the ingenuity of comptroller engineer screw often overcome these challenges by producing a obliging piece of equipment. closelyly, proportionate-integral-derivative (PID) ascendences ar economic consumptiond for suave level mince in most applications and stool be utilize to m any industrial processes and automatonlike trunks. PID ascendancys proven to be a perfect command for aboveboard and e wantated processes, but when it comes to controlling of non-linear and multi changeable processes, the controller parameters incur to be uninterruptedly adjusted (Bhuvaneswari et al., 2008). In process control placements, nonlinearity is the rule rather than the exception. Most control twines such as pressure, temperature, composition, etc., argon significantly nonlinear. This whitethorn be because of non linearity due to control valves, or on account of variations in process gain, conviction everlasting, and dead snip, as discussed in (McMillan et al, 1994). Therefore, the study of control brass has contributed to huge impact positively to our modern day development.A engraft can be controlled manually or robotically and the control frame consists of a embed with its actuators, sensing elements and a controller. Manual controlling process of a seed down cannot be as accurately enough likend to automatic control. An automatic controller is made up of device, electronic circuit, computer, or mechanical linkage etc. The interface between the plant and the controller requires actuators (control elements) to provide control action.In instrumentation, detectors and demodulators ( appraisement elements) are needed to provide in pee-peeation close to the plant status to the controller (Golten and Verwer, 1991). However, the most important characteristic of a plant is its sta bility, which indicates that a clay can be control smoothly without unwarranted oscillation or overcorrection. The behaviour and performance of a control constitution depends on the interaction of the entire element. The difference between the identify-point and the real comfort of the variable is called hallucination. An opposite important characteristic of a control system is how quickly it can respond to an fallacy and correct it. The smaller the faulting, the bettor it would be for the control system.The basic types of process control are collapse loop and closed loop system.+ The open loop system has no feedback because it has no sensor to sense the fluid level in the tank. spell the closed loop system is characterised by a sensor and a feedback foretell which carries information from the measurement device to the comparator. Typical actuators employ in liquid level control systems include pumps, motorised valve, on-off valves, etc. In addition, level sensors such as displacement float, capacitance probe, pressure sensor (Bateson, 1999), etc., provide liquid level measurement for the purpose of feedback control.In a closed loop feedback control system, the forward path transfer juncture is G(s) representing the process or plant universe controlled together with any controller projectiles. The feedback path transfer modus operandi, H(s), represents the measurement system or transducer which provides the feedback prefigure (Golten and Verwer, 1991). The kettledrums suit transfer function relating the controlled variable Qo to the desired grade or extension, Qi isQiQoFigure 1 Closed loop block drawHence, the procedure of deriving the equivalence above can be bring in the appendix page.In addition, the prime objective of feedback control systems is to under maintain the differences between the fruit and the reference insert since this represents the error. The control system should be quick as possible in reducing this error to ho me in (or to some reasonable low protect) when thither is either a whirl or change in reference apprise (Golten and Verwer, 1991).Feedback has similar advantages when applied to automatic control system, it has the ability of controlling a system that deals with unheralded disturbances that cogency occur inwardly the system and adapt to changes in the plant. Therefore, with the development of electronics and its applications, the understanding of close loop control system cast upd rapidly, since feedback amplifier is essential (Healey, 1975). A simple control system is utilise to maintain a unbroken weewee level in a tank, example of such is toilet systems in various homes. The swinging ramification attached to the foreplay valve of the WC body of irrigate tank allows peeing to menstruum into the tank until the float rises to a point that closes the valve. When the water level is low in the tank, the swinging arm moves downwards which allows more water to prevail into the tank. This continues until the swinging arm returns to its initial state. This is a simple and effective level control system for water tank.Another level of control system is a steam boiler where the level of the water in the boiler essential be keep between certain(a) limits otherwise, it may lead to serious damage to the boiler and expression as well as cause hazard to the building occupants (Miller et al, 2004). Water gages serves as a means of measurement level in the boiler. In an engineering context, the addition of control systems essential be warrant in terms of their profitability, or environment safety. A control system must be effective and efficient, and remain so throughout the bearing of the plant (Dutton et al., 1997). The performance of a system is often expressed in terms of their parameters such as speed of response, stability and calm down-state error. A dandy speed of response may often be progress tod at the spending of steady state error a nd stability (Premier, 2008)1. Stability is one of the most important characteristics in any system. For a system to be stable, the system components must be appropriately sized for the application and the system must be correctly adjusted (tuned).The objectives of this project is to investigate the control of water level in non-linear water tank which is fed by a centrifugal pump and discharges to a sump tank through a valve. The tank is a V shaped tank which has a uncoiled wall. The system in shine would be adjusted alongside with the control signal to the outlet valve and the outlet pump during the simulation.Furthermore, the project task includes formulateing a comparative (P) only and proportional + integral (PI) controller for a special(prenominal)ized run point and implementing it as an analogue s-domain system. The objectives would be accomplished by examining the dynamics of the water tank, good exampleling it from first patterns and by applying dance step tests to localise the system model at various workal points. The plot at a lower place shows the equipment used to carry out the experiment.Figure 2 Water tank level control systemFigure 4 Block diagram of V Shaped Tank systemAIMTo characterise a new V tankConduct identification and control experimentationComparing it with an existing replicate systemOBJECTIVERelating level control to industrial applications.Understanding the dynamics of water tank, modelling it from first principleApplication of step-test to identify the system model at various operating points.Designing a proportional + integral controller for ad hoc operating point.1.1 EXPERIMENT COMPONENTSIn order to perform the laboratory experiment on process plant (V-tank), the experimental components used are amplifier, sensor transducer, water tank, valve, and pump which are discussed below.1.1.1 AMPLIFIERThe amplifier is a real important part of any control system. Basically, it is used to deliver an turnout signal which i s larger, in a prescribed way, than the foreplay signal. A good designed amplifier mostly requires that the excitant impedance should be large so that the source is not ludicrous, and the product impedance should be small so that the power element can be easily driven (Anand Zmood, 1995)2. An amplifier could be referred to as the signal conditioner use in this experiment. An amIn measure width modulation (PWM) the premium and repetition rate remain unbroken, and the width of the pulse is varied consort to the modulation signal amplitude (Parr, 1996)3Pulse Width modulate (PWM) signals are increasingly being used to drive continuous actuators such as d.c. motor, hydraulic servos and a.c. motor. If the switching frequency of the PWM amplifier is sufficiently high in affinity to the actuator time constants, because the signals allow be average around the measure out (Olsson Piani, 1992)4. The motor is driven by a Pulse Width Modulated (PWM) power amplifier, which supplies power to the motor proportional to a cinqueage signal from the controller.Pulses are produces at regular intervals, the duration or width of the pulse being proportional to the size of the voltage at each of the propagation concerned (Bolton, 1991)5. The reason why pulse width modulation is used is that conventional power amplifiers would simply burn at high power levels. The advantage of switching is that the solid-state devices are not continuously loaded with high power and therefore their power dissipation is low. This fact makes PWM amplifier very efficient. In PWM amplifier, the switching can be directly controlled from the digital output ports of a computer.1.1.2 SENSORIn virtually every engineering application, there is the need to measure some physical quantities, such as displacements, speeds, forces, pressures, temperatures, stresses, flows and so on. These measurements are performed exploitation this physical device called sensors, which are capable of converting a ph ysical measure to a more readily manipulated electrical quantity (Onwubolu, 2005). A sensor could be referred to as transducer. Although, there are antithetic kinds of liquid level transducers which are used in variety of control applications with varied function such as float-type liquid level transducers, hydrostatic pressure liquid level transducers, capacitance probes, and so on. But with heed to this project, the pressure transducer will be the point of focus. The pressure transducer is used to measure the height (or intellect) level in the tankFor a sensor to function effectively there is a need for signal conditioner and a ostentation system. This signal conditional obtains signal from the sensor and manipulates it into a condition which are suitable either for display, or control system usefulness. Hence, a display system shows the output readings from the signal conditional (Bolton, 1999)6.Since the dynamic and static characteristics of the sensor or measuring element affect the indication of the actual value of the output variable, wherefore the sensor plays an important role in ascertain the overall performance of the control system. The sensor usually determines the transfer function in the feedback path. If the time constants of a sensor are negligibly small compared with other time constants of the control system, the transfer function of the sensor simply becomes constant (Ogata, K., 1997).In selecting a good transducer with respect to its performance and system measurement, certain criteria had to be fulfilled. The accuracy of the transducer to which it has been calibrated, its response to error within the system, its stability i.e. the ability of the transducer to overturn the same output reading when used to measure a constant input over a period of time, etc (Bolton, 2008)7.1.1.3 WATER armoured combat vehicleWater tank is aThe tank characteristics are non linear depending on the operating point and are such that tank level come to the fore is a function of the level.Figure 5 Tank fluid level systemThe objective of the controller in the level control process is to maintain a level set point at a given value and be able to accept new set point determine dynamically and this level control system must be controlled by the proper controller. In passing the top section of the tank as shown in fig. 5 above, the flow-rate can be calculated victimisation Bernoullis equation. From Bernoullis law the flow through a valve q (m3s-1) is related to the pressure gaffer crosswise the valve h (m) by the following equation, in which g is the quickening due to gravity, Cd is the coefficient of discharge (m2) (Dutton et al., 1997).Modelling the TankThe tank can be modelled from first principles with the provision of certain assumptions. For the sake of simplicity, it is possible to consider the top section of the tank with parallel sides and then extend this model to deal with the whole tank. The prismatic section of the tan k can be considered to be a simple rectangular tank with an inflow Q and an outflow, QL as in Figure 2. By considering conservation of matter, we can say that the flow into the tank must be equal to the flow out plus the flow converted into a change in level.but if then1.1.4 VALVEControl valves are commonly encountered elements in process plant and the equation that describes their flow behaviour are nonlinear. Other nonlinear effects may exist because of the valve characteristic and the equipment surrounding the value. Control valves are used to ordinate the flow rate of fluid in a system. The control of flow rate can be achieved by varying the size of the portrayal through which the fluid flows (Stenerson, 2004)8. The control valve modulates the flow of a fluid by introducing a variable area aperture into the pipeline. The volumetric flow rate, Q, of a particular liquid through a valve is proportional to the pressure drop across it, P.Thus, let kv be the valve coefficient which is the function of the valve opening or lift, h. in order to avoid dimensionality, the lift, h is defined as a uncomplete lift, i.e. when h is 1 the control valve is fully open, and when the h is 0 the value is shut.1.1.5 VANE PUMPIn selecting a pump for a specific task, there are certain factors that needs to be considered such as the height at which the pump will be moving the liquid to, the speed that is required, and the pressure flow at the pumps outlet. A pump is a mechanical device that changes mechanical power into fluid power. Positive displacement (PD) pumps perform work by expanding and then compressing a cavity, space, or moveable boundary within the pump. In most cases, these pumps actually captured the liquid and transport it through the pump to the discharge nozzle (Bachus Custodio, 2003)9. However, the flow through PD pump is mostly a function of the speed of the driver or motor. A D.C motor drives the pump at a constant speed in most cases so that the delivery wo uld be constant, i.e. the flow Q is normally constant (Healey, 1975).The pressure or query that a PD pump can generate is mostly a function of the oppressiveness of the casing and strength of the associated accompanying parts (seals, hoses gaskets). In addition, a PD pump has been designed to have some exigent tolerance parts. This strict tolerance controls the flow, and pressure that these pumps can generate. The ability to pressurize the fluid to higher(prenominal)(prenominal) pressures will depend on the tolerance of the components within the pump. Hence, the closer the pumps tolerance, the higher the capabilities would be (Brumbach Clade, 2003).10Furthermore, there are three types of positive displacement pumps in use nowadays which are vane pump, gear pump and the diver pump. These kinds of pump had different similarities depending on their performance but based on this task it would be concentrated on vane pump. vane pump are used in hydraulic systems. When the rotor rot ates the pumps vanes in a counter clockwise direction which caused the vanes to slide in and out of their slots within the pump ho use, a large amount of fluid would be carried from the doorway to the outlet (Onwubolu, 2005)11. This results from the eccentricity of the centre of the rotor with respect to that of the housing.Figure 3 leaf blade Pump1.1.5.1 PUMP TESTIn order to examine the pumps accuracy, a test was carried out on the pump. The pump was used to move water from one container to the other within a time limit. Using the laboratory scale machine, the empty container was measured to weighs 0.585Kg. However, the pump was tested at different voltage supplied to the pump from 1v 10v at every one minute and then measured the filled container to know the actual weight. The reading was measured in kilogram (kg) which was converted to litres per minute. The conversion was 1kg to 1litre at a constant time. The emergence of the pump testing experiment could be seen in the graph below.Graph 1 Outcome of Pump Testing GraphIn addition, the pump testing results obtained from the graph above shows that the pump was not functioning perfectly. The inaccuracy of the pumps energy is as a result of imbalance modified vanes inside the pump. The actual dimension of the vane inside the pump was 8mm inner diameter, 52mm outside diameter and 22mm thickness. The out diameter of the vane was cut-down or modified to roughly about 40mm for the vane to rotate easily within the casing. Hence, the graphs shape should be linear and not the linear curve shape in graph 1. From this experiment, it was notice that at any increase in voltage supplied to the pump there will be large amount of pressure increase from the flow outlet and vice versa.PumpFigure 4 Modified Vane SizeFigure 5 Actual Vane Size2. LITERATURE REVIEWLiterature review3. CONTROLLERA controller is a device which monitors and influences the operational condition of a given dynamical system. In closed loop control s ystem, a controller is used to compare the output of a system with the required condition and convert the error into a control action designed to center error. The error might be as a result of some changes in the conditions being controlled or because of changes in the set value. Most industrial controllers use electrical energy or pressurized fluid such as oil or tonal pattern as power sources. Controllers may in any case be classified agree to the kind of power employed in their operation, such as pneumatic controllers, hydraulic controllers, or electronic controllers. For this kind of controllers to be used for a particular task, it must be based on the nature of the plant and the operating conditions (Ogata, K., 1997)12.3.1 P ONLYWith proportional control the change in the controller output from the set point value is proportional to the error (Bolton, 1991)13. This means that the correction of the control element such as valve will receive signal which depends on the size of the correction required.Although, a system with a proportional control may have a steady state offset (or drop) in response to a constant reference input and may not be entirely capable of rejecting a constant disturbance (Mutambara, 1999). For higher order systems, large values of the proportional feedback gain will typically lead to instability. For most systems there is an speed limit on the proportional feedback gain in order to achieve a well damped stable response, and this limit may still have an unacceptable steady state error. Therefore, there is a limit on how much the errors can be reduced by using proportional feedback only. One of the ways to improve the steady state accuracy of the control system is to introduce integral control.Set pointError sour variableAmplifierActuator signalPlant3.2 P+I CONTROLLERThe simple reason for integral control is to reduce or eliminate constant steady state errors within the plant or system. Several limitations of proportional contro l are resolved by integral control. The steady state response to this class of load disturbance is completely eliminated. Thus, as long as the system remains stable, the system output equals the desired output regardless of the value of KP and its dynamic response (Mutambara, 1999)14. If the designer wishes to increase the dynamic speed of response with large integral gain, then the response of the system becomes very oscillatory. Hence, in order to avoid this oscillatory behaviour of the system then both proportional and integral control should be used at the same time.Set pointErrorProcess variableAmplifierActuator signal3.3 PID CONTROLLERMost industrial processes are controlled using proportional-integral-derivative (PID) controllers. The popularity of PID controllers can be attributed to their good performance in big range of operating conditions and partly to their functional simplicity, which make it easy to manoeuver (Dorf and Bishop, 2005)15. PID controllers are so effecti ve that its controlling ability are standard in processing industries such as petroleum, refining, etc.In order to design a particular control loop system, the constants value of KP, KI and KD had to be adjusted to an acceptable performance.Increasing KP and KI tends to reduce system errors but may not be capable of also producing adequate stability, while increasing KD tends to improve stability. The combination of the three control components in this system yields complete control over the system dynamics. The proportional-integral-derivation (PID) controller provides both an acceptable degree of error reduction and an acceptable stability and damping.4. METHODOLOGY4.1 STEP-TEST EXPERIMENTThe first part of the laboratory experiment involves ascertain the theoretical model at various level (h) of the water tank which include the prismatic bottom of the tank, the V shaped section and the top parallel sides of the tank. The water level in the tank was measured by a pressure sensor w hich was calibrated in the instrumentation laboratory prior to the experiment which showed that the pressure transducer produced a voltage signal proportional to the head.To bugger off this experiment, the centrifugal pump was switched on and the laboratory View step input political program was opened. The centrifugal pump was used to fill the water tank from a rectangular sump tank and also ensuring that there was enough water in the sump tank to perform the experiment. Although, the control valve was ensured to be fully open so that there would be continuous flow of water from the sump tank into the main tank as a result of constant running of the pump.After warming up the pump for some time, the pump bias was then set on the Lab View program to 1.3 volts (constantly) were the water is just about to start dropping into the tank. Using one second sampling time, the step volt was increased repeatedly by an additional 0.1 volts each time the head (h) settles from 0v 0.1v, 0.1v 0 .2v, and so on. As a result of increases in voltage, the water level would be increased as well in the tank. Once the water level reached the top of the tank, in order to prevent the water from luxuriant the step volt was reduced back to zero volt (0v) which allows the water to be empty back into the sump tank from the main tank and data or result was collected from the PC.4.2 P ONLY EXPERIMENTIn order to perform the P only experiment, the proportional gain has to be calculated to get the accurate value that would be input into the system. The proportional gain value can then be input into the LabVIEW package to run the experiment. The set point can be changed form one point to another to see how the plant would responds to the sudden changes to increase in set pointThe second part of the experiment entailed the design of the P only controller and P + I controller.As regards to the P only controller, once the values of the steady state gain and time constant were found from the ini tial step input experiment, the next step was to design a P only controller which will give closed loop dynamics 1/3 that of the open loop plant, which was then used to calculate the values of Kp at known head (h). Having calculated the Kp values, the pump was then switched on and allowed to warm up, also the Lab View P only controller programme was initiated. With the pump warm up up the Kp value was then entered into the P only controller programme alongside the same value for the pump bias and the sample time used in the previous experiment, i.e. 1.28 volts and 1 seconds respectively. The P only controller programme was allowed to run and the results for the sensor output (volts), the error (e) and the control feat were recorded and retrieved.4.3 P+I EXPERIMENTFinally to control the level of water in the tank and eliminate the steady state error the Proportional Integral Controller experiment was initiated, the hf (design level to which the tank is to be controlled) was defined and further derivation resulted in two unknowns, Kp and TI. The values for Kp and TI were then calculated for, then input into the Proportional Integral Controller program and allowed to run with a sample time of 1 seconds. The results for the sensor output (volts), the error (e) and the controller output were recorded and retrieved.5. RESULTS DISCUSSION ANALYSIS5.1 SYSTEM TRANSFER FUNCTIONAMPLIFIERWATER TANKSENSORCONTROL VALVEPUMPPROPORTIONAL ONLYPROPORTIONAL PLUS inherent5.2 SYSTEM MODELLING5.3 SYSTEM PERFERMANCE5.4. RESULT DISCUSSIONGraph 1 Step-test experiment of voltage against time.Graph 2 Step-test experiment of voltage against time6. CONCLUSIONFUTURE WORKFilter design discussion tone reducer7. REFERENCESBateson, R.N., 1999. Introduction to control system technology. 6th ed. Upper saddleback River, capital of the United Kingdom Prentice-Hall.Bhuvaneswari, N.S. Uma, G. and Rangaswamy. T.R., 2008. Adaptive and optimal control of a non-linear process using intelligent contro llers. Applied Soft Computing e-journal (9) pp.182-190. Available through lore Direct database Accessed 26 November 2010.Dutton, K. Thompson, S. and Barraclough, B., 1997. The art of control engineering. Harlow Reading, Mass. Addison Wesley.Girdhar, P. and Moniz, O., 2005. Practical centrifugal pumps design, operation and maintenance. Oxford Newnes.Golten, J. and Verwer, A., 1991. Control system design and simulation. London McGraw-Hill.Healey, M., 1975. Principles of automatic control. 3rd ed. London English Universities Press.Miller, R. Miller, M.R. and Oravetz, J., 2004. Audel Questions and Answers for Plumbers Examinations. USA Wiley Publishing.Shinners, S. M., 1998. Modern control system theory and design, second ed. Canada John Wiley Sons, Inc.Wahren, U., 1997. Practical introduction to pumping technology a basic turn tail to pumps. Houston Gulf Pub. Co.