Design and Simulation of Automatic Load Tap Changer

initiation and Simulation of Automatic preventive Tap record changerIntroductionCE 3.1This is the third jutting I did as a graduate galvanic Engineering while pursuing my Bachelor of Engineering in the country of Electrical Engineering from Balochistan University of Engineering and Technology, Balochistan, Pakistan. I wanted to conduct a project that would enable the transformer to attain different emf levels using a fill up blame changing transformer and thus wanted to go totally oer rough different electrical/electronic comp one and further(a)nts that would be needed and thus look out about its design and how to implement it. I was able to improve my create verbally and oral presentation skills as well as my interpersonal skills by the successful completion of this project.BackgroundCE 3.2For my third project as an undergraduate in electrical engineering, I wanted to start croping(a) on a project during my second year. I wanted to learn about the different and co mmonly employ electrical/electronic components, the functional mechanism and the implementation in complex projects. This served as a motive to conduct a project on deprave Tap changers.I had studied during my bachelors that Transformer Load changers argon an integral part to any baron grid whether in big projects or small. I knew that on that point were the automatic Load tap changer and the Electronic Load Tap Changer. I wanted to design an automatic Electronic type Load tap changer to the problems with reliability and maintenance of the Mechanical type.Also, I learned that by using Thyristors to take the on-load current while the main contacts change over from one tap to the next, the design would have no moving part and thus have a longer service life. And it is due to this earth that I selected the Design of Automatic Load Tap Changer for my project.CE 3.3The objective of this project is to design and wee-wee a prototype of a fully electronic on load tap changer for baron transformers by using Triacs as switching devices and microcontroller as the triggering circuit.CE 3.4CE 3.5I successfully completed this project by engaging in the following activitiesI divided my project into Power circuitry and Control circuitry.I designed the power circuitry to basically consist of a tapping transformer connected to the load through the switching devices.I designed the Control circuitry to sense the voltage bespeak fed from the blackguard ingest transformer and compare it to a pre-set reservoir apprise.I used a Triac which is a three terminal semiconductor device for controlling the current in both directions.I used a Power Circuit, Microcontroller Unit, linear To Digital Converter, Zero Crossing Detector, Multiplexer, LCD, Buzzer as the parts of the circuitI completed the project within the mea sure as shooting frame specified by the university.I conducted detailed literature freshen up on all the components used here.Personal Engineering Activ ityCE 3.6I approached a professor with an idea of conducting a project with transformers. along with my team mate, I had a lot of brainstorming sessions and review meetings with my project supervisor to select a suitable topic. I suggested that I conk out on a project that was concerned with designing and fabricating a corpse based on Automatic Electronic Load Tap Changer of a Transformer and the supervisor agreed to this and asked us to begin working on this by first conducting a literature review on all the components we would require and the working of this project and to start working on this project.CE 3.7I first started with the design of the Power circuitry which consists of our main Tapping Transformer. The tapping is provided at 231V, 225V, 220V, 214V, 209V and 0V. Furthermore, I clear-cut to incorporate BTA16 Triacs. I also decided to build a snubber circuit using 100 resistor and a 104pF capacitor.I decided to use the Triac instead of the SCR because a triac operates i n the same way as the SCR however it operates in both forward and reverse directions. Also, I had to visualize the TRIAC will turn off correctly at the end of all(prenominal) fractional-cycle of the AC power. And due to this reason I used the snubber circuit to serve up in the turning off and on. I used a MOC 3021 to go to with this.Circuitry DiagramThe following are the components I used for this project I used the AT80S8252 Microcontroller or the 89C52 which is a high performance CMOS 8bit microcomputer of sorts. ADC 0804 Analog to Digital Controller which feeds the comment to the microcontroller. I used a mistreat down transformer to provide samples to the ADC of the load.- Zero Crossing Detector to provide the needful pulses for the AND logic along with the multiplexer. A Multiplexer or Mux is a device that selects one of several latitude or digital introduce signals and forwards the selected input into a single line.In my project, the Interlocking mechanism is achiev ed by using Multiplexer. Thus, at any instant of time, no two triacs would be in their ON STATE. This is particularly important and advantageous in case the logic of microcontroller fails. I used a Liquid Crystal Display (LCD) to display the return voltage that would be across the load side. I used an Optocoupler MOC 3021 to designate signals between different elements of a circuit.CE 3.8The following is the manner of the working of this project using a block drawThe block diagram shows the basic strategy, as to how the Load Tap Changer will work automatically. I used TRIACs as the switching devices.I made sure that the The transformer has five tappings at the voltage level. Each of these tappings is connected to the one of the main terminals of the TIRAC. The second main terminals of all the five TRIACS have been shorted. So at any given time when any of the TRIAC has been switched on there is only one conducting path to the load.I used a step down transformer to step down the voltage level to instrumentation levels so that it sess be used in the control circuitry. As the voltage increases or decreases depending on the nature of the load the voltage at the primary of the step down transformer varies, resulting in an equivalent variation at the secondary side.I then had to make sure that this sampled AC voltage is rectified to an roughly smooth DC value. This DC voltage is then fed to the analog to digital converter, which gives a digital take that can be tacit by the microcontroller. The ADC output is fed to the microcontroller which had been already programmed to compare this incoming value to a set of predefined values and send a high signal on one of its port bits. The output of the microcontroller is fed to a multiplexer. It is integrate to ensure that at any given time, even if the logic fails there is only 1 conduction path to the load. I.e. only one TRIAC is switched on at any grammatical case in time.I also used the zero hybridizing sensing element in order to detect the instance when the AC voltage crosses the zero amplitude mark. The output of this zero miscegenation detector is in the form a pulse generated every half cycle.I then fed the output of the zero crossing detector and the multiplexer to the AND logic as shown in the diagram. Each time the zero crossing detector gives an output, a pulse is generated at the output of the AND logicThis output of the AND logic is basically our trigger signal for the switching devices i.e. the TRIACs however in order to isolate the control and high voltage circuitry and to implement DC triggering on the TRIACs operating at AC voltages the Optocouplers have been incorporated. So basically the Optocouplers are only there to provide isolation.CE 3.9The following are simulation results I obtainedWhen input is 220v, the Triac on Tap 3 is on.When the input is 225v, the Triac on Tap 2 is on.SummaryCE 3.10 I successfully completed the project titled Design and Simulation of Automati c Load Tap Changer along with my team mate. I learned how to build a circuit board and how all the different electrical components palaver to each other in this project. I learned how important the Load Tap Changer is for any power grid and how useful it is over the Mechanical type Load type changer.By successfully terminate this project, I was able to improve my written, oral and interpersonal skills.