Figure on the right shows how dramatically the reactive power demand from the network increases as the generator departs from a tight slip regime. Induction motor with reversing stator magnetic field. Going from engineer to entrepreneur takes more than just good code (Ep. Type 1: It consists of a squirrel cage induction generator connected directly to the power grid. I suspect I am fundamentally misunderstanding the working principles of induction generators. In doubly fed wind power generation systems, the capacity of rotor side converter is small compared with the rated capacity of generator, the rotor side converter can provide partial control of the generator. . An induction generator is essentially an induction motor where the slip is negative, i.e. and the three links in that answer. Description The wind turbine and the induction generator (WTIG) are shown below. Academia.edu no longer supports Internet Explorer. The DFIG system consists of a wound rotor induction generator connected to two back-to-back connected power converters: the grid side converter (GSC) and the rotor side converter (RSC). <>/Font<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.44 841.68] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> The surplus power produced by domestic microgenerators can, in some jurisdictions, be fed into the network and sold to the utility . Abstract. At the starting, the machine draws the lagging reactive volt-amperes from the supply mains. Available: http://www.osti.gov/bridge/servlets/purl/1051403/1051403.pdf. About over speed do not apply here because it is being driven by an induction motor that cannot over speed. Does English have an equivalent to the Aramaic idiom "ashes on my head"? The U.S. Department of Energy's Office of Scientific and Technical Information The induction Generator is also known as Asynchronous Generator. For those of you who want to see the math there is plenty covering the subject on the internet just ask Google. Why don't American traffic signs use pictograms as much as other countries? As to the questions of power capability it is better to use many such machine combinations coupled in parallel to one bus-bar. 5) Can I run a 50Hz motor on 60Hz power supply? Most wind generators installed at the end of the 20th century were ordinary asynchronous (induction) generators, usually with fixed capacitance to correct for the reactive power demands of that type of generator. Yes, the rotor field is aligned with the stator field. Method for suppressing voltage fluctuations of gridconnected doubly fed induction generator based on mathematical mechanization theory Xiangyu Wang, . Download : Download high-res image (133KB) Download : Download full-size image; Fig. Stack Exchange network consists of 182 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. A new STATCOM based Reactive Power Management in Grid Connected DFIG based Wind Farm July 2019 International Journal of Innovative Technology and Exploring Engineering 8(9):293-299 When the migration is complete, you will access your Teams at stackoverflowteams.com, and they will no longer appear in the left sidebar on stackoverflow.com. For a three-phase Induction motor if the rotor is coupled to the Read more Electrical Machines Doubly Fed Induction Generator , Grid-Connected Induction Generator , Induction Generator Types , Induction Generator vs Synchronous Generator , Self-excited Induction Generator In grid-connected mode of operation, one of the two three-phase winding can be connected to a customer loads as and when required. 1. Look at my answer to Can someone verify my understanding of induction motors? Wind turbines with squirrel-cage induction generators connected directly to the line are the simplest electrically. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Oct 22, 2015. It is totally self-synchronizing with the grid it is feeding power into. SIMULATION OF GRID CONNECTED INDUCTION GENERATORS FOR POWER QUALITY IMPROVEMENT ABSTRACT-This paper distinguishes the performance of wind power systems for two types of induction generators to have better performance and maximum extraction of power using FACTS devices. x]ko6>}D#.bvf:Ml|p|I-M)/b0-rx9W_r:?]7-Wj3VN|:)U:QEV*UVd~zz6_^D"tAEIUL5t[$\kv*,3Ree=hY@K}0d"d@j%&/60@^En{QnR)r|w>ij%r,mB}>X.e&qW!0O%=2k3B7YQ)Rd @'R New 2023 THOR MOTOR COACH MIRAMAR 37.1 For Sale In Wixom, Michigan. Did Great Valley Products demonstrate full motion video on an Amiga streaming from a SCSI hard disk in 1990? The driving motor must have sufficient torque to drive it at that speed against the back EMF coming from the grid it is feeding. Induction generators are not used in current turbines. Distributed Energy Resources (DER) Working Group, Operations and Maintenance (O&M) Users Group, System Operation & Market Design Working Group. For the machine shown, rated slip is about 0.8%, at which point the machine would draw 340 kVAR from a line with rated voltage. Why does the stator field rotate at the same speed as the rotor field in a synchronous generator? In the case of a four pole induction generator feeding a 50 Hz power supply it will deliver max power when its speed is 1575 to 1600 rpm. Stock Number: 2016886-280380. DFIG based wind turbine with crowbar protection DFIGWIND TURBINE Crowbar protection converter Inductor and resistors To grid. In order to analysis of the grid connected induction generator under fault conditions, three different cases are analyzed. I believe they are saying that a grid-connected induction generator takes a -90 degree phase shifted magnetization current from the grid and produces an output current through a load in phase with the grid voltage. It is totally self-synchronizing with the grid it is feeding power into. Consequently, the dynamic model of double fed wind turbines, converter model and grid model were established to study the transent . [ RY*06~i[,>N{%i @o%b!3 _URY75Z!W!F D(!? The change in modal properties for different system parameters, operating points, and grid strengths are computed and observed. <> Synchronization of power supply is two power sources connecting together. Fig. Drive Side: Left Hand Drive. I need to test multiple lights that turn on individually using a single switch. generally a one operates as generator power is sends to electrical grid. Figure 4 shows a 40 kW (medium-size) three-phase induction generator for a wind turbine. endobj " In other words gents the sync is independent of speed. The stator winding is connected directly to the grid and the rotor is driven by the wind turbine. The best answers are voted up and rise to the top, Not the answer you're looking for? How does an induction generator work? Owing to a direct link through stator windings, a DFIG is significantly vulnerable to grid disturbances and experiences sizable . legal basis for "discretionary spending" vs. "mandatory spending" in the USA. To learn more, view ourPrivacy Policy. Concealing One's Identity from the Public When Purchasing a Home. A detailed model of the backlash in its gear-train which couples the wind turbine to the DFIG, has been derived based on a two-mass drive-train model. What's the proper way to extend wiring into a replacement panelboard? The straightforward power conversion technique using SCIG is widely accepted in fixed-speed applications with less emphasis on the high efficiency and control of power flow. Consequences resulting from Yitang Zhang's latest claimed results on Landau-Siegel zeros. All rights reserved. If single phase supply can not create rotating MMF, how does Induction motor generate torque? But what if we want to use an induction generator to supply a load without using an external source (e.g. Thanks. You can download the paper by clicking the button above. a magnitude and frequency control (mfc) strategy has been used for the grid connected doubly fed induction generator (dfig).the proposed mfc makes the dfig equivalent to a synchronous. Glycerol, a large-volume by-product of biodiesel production, is a potential feedstock for the production of low-carbon energy vectors. One of the important features that make the synchronous generator an unrivaled alternative for power generation is its stability properties and inherent inertial response. 503), Fighting to balance identity and anonymity on the web(3) (Ep. By matching motor and generator efficiency of > 75 % is easily achieved while both machines are operating close to full load rating. A typical DFIG system is shown in Fig. Modal Analysis of Grid-Connected Doubly Fed Induction Generators Abstract: This paper presents the modal analysis of a grid-connected doubly fed induction generator (DFIG). MathJax reference. endobj Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site, Learn more about Stack Overflow the company. The induction generator has a squirrel cage rotor which draws magnetizing current from the stator giving rise to a high reactive power demand when fluxing, as when the generator circuit breaker is first closed. Which informations do I need to calculate the efficiency and horsepower of a 3 phase induction motor? I saw an answer to another question that stated: "An ordinary induction generator connected to a power grid will draw lagging reactive volt-amperes from the grid and supply real power to the grid. Number of Slide Outs: 3. When an induction generator is connected to a grid, it takes reactive power from the grid. Then the model of SPCS has been used to analyze the performance of same rating WRIG (at same given wind speed). Stack Overflow for Teams is moving to its own domain! So this means that the current induced by the rotor field is in phase with the stator magnetizing current. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. The rotor is a squirrel cage made with either aluminium or copper bars. I thought an induction motor ran above synchronous speed worked as a generator because above synchronous speed the rotor cuts the stator flux in the opposite direction as below synchronous speed, therefore inducing currents in an opposite direction and a magnetic field of opposite polarity as before in the rotor. megawatt (1 mw) wind turbine for one year can displace induction generators can be divided into two types according over 6.5 tons of sulphur dioxides, 3.2 tons of nitrogen oxide, to source of reactive power first is standalone generator and 1,500 tons of carbon dioxide and 1 0 obj The corresponding mode of operation of induction machine is called generating mode & the slip of induction machine . Did find rhyme with joined in the 18th century? When connected to the grid, SCIGs can supply power at grid frequency irrespective of the wind speed. Now if you drive it with an induction motor connected to another grid which has its own variations in frequency. Grid-connected domestic wind turbines may use grid energy storage, thus replacing purchased electric power with locally produced power when available. The studied systems with single induction generator under . 1. Concerning the modelling of induction machine, a fifth-order model in dq 0 frame presented in [ 1 ] is used for simulation of the induction generator (IG), which allows the study of . While, the load absorbs the active and reactive power (Pl, Ql) from the grid system and/or the induction generator. If it is feeding a 50 Hz power supply it must be driven 2% to 5% above ts sync speed. If the slip were increased to just 1.0%, the reactive power requirement increases to almost 480 kVAR. Grid connected-induction generator start-up sequence observation using laboratory simulator @article{Wijaya2015GridCG, title={Grid connected-induction generator start-up sequence observation using laboratory simulator}, author={F. Danang Wijaya and Eka Firmansyah and Sarjiya and B. S. M. Isnaeni}, journal={2015 IEEE Innovative Smart Grid . The current that the motor produces as a generator is produced in the rotor and passed to the stator by transformer action. Note that the motor slip "s" is negative when the motor is acting as a generator. The prepared model of GIG using IVCS are analyzed such that an optimum value of input voltage is found i.e. (Qg) from the excitation capacitor (Qe)or/and grid system and produces the reactive power when the capacity of the excitation capacitor more than reactive power that is required by induction generators. 1) Modify GoHz Single Phase 240v Converter to Split Phase 120v/240v, 2) 3 Phase Motor Running on Single Phase Power Supply. Thanks for contributing an answer to Electrical Engineering Stack Exchange! According to emergency grid rule requirements, wind farm should has the ability to stay connected and continue generation under external voltage failure conditions, that is, wind turbines have to keep in connection with grid and own continue power supply. The power captured by the wind turbine is converted into electrical power by the induction generator and is transmitted to the grid by the stator winding. Wiring a VFD to control single phase motor speeds, Difference between 50Hz and 60Hz frequency, Impact of 60Hz (50Hz) motor being used on 50Hz (60Hz) power supply, Induction generator synchronization with grid. Why was video, audio and picture compression the poorest when storage space was the costliest? 4. ;Different from the grid-following structure, the doubly-fed induction generator (DFIG)-based wind turbine with a grid-forming structure has no coupling between the current loop and the phase-locked loop, and has a certain frequency/voltage active support ability, so it is more suitable for operation in the weak grid. This is a question about squirrel-cage induction machine theory. show the induction generator which is driven by the prime mover such as a wind turbine is connected to a load. Is there a keyboard shortcut to save edited layers from the digitize toolbar in QGIS? Enter the email address you signed up with and we'll email you a reset link. In case of standalone IGs the magnetizing flux is established by a capacitor bank connected to the machine and in case of grid connection it draws magnetizing current from the grid. Positive torque means the machine is acting as a motor and negative torque means it is operating as a generator. In this video, You will learn how to simulate grid connected induction generators using MATLAB/Simulink.#induction_machines#induction_generators#MATLAB_Simul. #1. Connect and share knowledge within a single location that is structured and easy to search. While for purposes of aerodynamic efficiency they operate at nearly constant speed, the slight variation of speed with torque (and power) can significantly reduce mechanical torque transients associated with gusts of wind and grid-side disturbances. The torque is proportional to the sine of the angle. For a four-pole motor (two pairs of poles on stator) powered by a 60 Hz source, the synchronous speed is 1800 rotations per minute (rpm) and 1500 RPM powered at 50Hz. Please correct my errors in thinking. The DFIG is equipped with the control for maximum power point . If this is correct, I am a little confused. In addition, the active and reactive power balances in the induction generator can be written as follows: P produce = P absorbs Q produce = Q absorbs Induction Generator Modeling The induction generator modelling is derived from an In this paper, the performance of a grid connected doubly fed induction generator based wind turbine (DFIG-WT) system is examined, in the presence of backlash in its gear-train. The ac voltage is typically increased to 12,470 V or more and connected to the grid. Can I run a 50Hz motor on 60Hz power supply? Grid connected Induction generator Connecting an induction generator to the grid requires reactive power, which is provided by the system. <> It stays in sync and delivers energy as long as it is driven at an rpm higher than its synchronous speed. Documentation, User Support, and Verification of Wind Turbine and Plant Models (DE-EE0001378), September 2012, [Online]. The U.S. Department of Energy's Office of Scientific and Technical Information When a short-circuit fault occurs on the transmission line, there will be an excess of electric power, but the power demand will increase instantaneously once the fault is removed. Could an object enter or leave vicinity of the earth without being detected? But the current producing the stator magnetic field is the magnetizing current, -90 degrees out of phase with the grid voltage. 6) Wiring a VFD to control single phase motor speeds, 7) Difference between 50Hz and 60Hz frequency, 8) Impact of 60Hz (50Hz) motor being used on 50Hz (60Hz) power supply. If the stator field leads the rotor field, the angle and the torque are positive. It has become fashion to have wind generators feed the grid via semiconductor conversion equipment, in some instances the harmonics are being generated in the RF range and 50 Hz and 60 Hz systems can be badly affected. Speed range 1530 to 1575. %PDF-1.5 The induction motor's speed will follow the frequency variations of the grid it is connected to and the induction motors speed variations will pass mechanically to the induction generator BUT THOSE SPEED VARIATIONS WILL HAVE NO EFFECT ON THE SYNCHRONIZATION OF THE INDUCTION GENERATOR with the grid it is feeding power to. Thank You in advance. It works very well except load regulation sucks if av held constant for maintain 60hz frequency I using 5HP (which is 3.729kw) motor for Gen. To allow for inefficiencies I decide full load should be 2.5kw. Why is there a fake knife on the rack at the end of Knives Out (2019)? Another advantage to induction generators is safety. For a given wind speed, the operating speed of the turbine under steady conditions is a nearly linear function of torque. Exterior Length: 39 ft. Based on the source of reactive power induction generators can be classified into two types namely standalone generator and Grid connected induction generator. grid)? The parameters of a DFIG may deviate from their rated values due to the . . Grid-Connected Induction Generator The stator of the Induction motor is connected to the line power source that provides excitation. induction generator working principle induction generator types 2 Induction motors get their excitation from the utility grid through a connection at the stator. Can lead-acid batteries be stored by removing the liquid from them? "An ordinary induction generator connected to a power grid will draw lagging reactive volt-amperes from the grid and supply real power to the grid. The motor always turns slightly slower than the synchronous speed. Assignment problem with mutually exclusive constraints has an integral polyhedron? from publication: Integral Sliding Mode Control for . Pertaining to the connectivity issues in wind power plants with grids, this study introduces an efficient mechanism based on a state feedback control structure to establish a fast and stable grid connection for a wind-driven doubly-fed induction generator (DFIG). the induction generator. When the speed of induction generator above synchronous speed the active power delivered by the 3- phase load. The speed of the machine is increased above the synchronous speed . If the rotor field leads the stator field, the angle and the sine are negative. 1 Introduction. With all these inherent advantages of six-phase induction generator, there is strong motivation to take a thorough investigation of six-phase machine from stability point of view. The conventional additional frequency control strategies of wind farms can effectively reduce the frequency fluctuation . However as the two fields rotate, they not directly aligned, there is an angle between them called the torque angle. Sections discuss induction . stream 504), Mobile app infrastructure being decommissioned, Armature reaction of a synchronous generator. When an induction generator is connected to the grid, the system supplies reactive power to operate the generator. Interior Color: ON ORDER. This paper focuses on the configuration of large Doubly Fed Induction Generator (DFIG) based wind farm connected into the grid. An induction generator produces electrical power when its rotor is turned faster than the synchronous speed. It is simultaneously a lagging power-factor load and a unity power factor supply.". <>>> The output of the induction generator will stay locked exactly to the grid it is driving into over that speed range. To browse Academia.edu and the wider internet faster and more securely, please take a few seconds toupgrade your browser. This paper analyzes both dynamic and steady-state performances of induction generators connecting to a utility grid. This paper explains the development of a mathematical model of DFIG driven by wind turbine. With fast increase of penetration level of wind generation in power systems, capability of fault ride-through (FRT) of grid-connected wind farms is required by the grid codes in many countries [].Doubly fed induction generator (DFIG) is a type of most-commonly used variable-speed wind turbine generators with multiple advantages in industrial applications []. Ht3]&u!:-^g3LPE#1f (oA@k|E4Hd Ws"iI?)h)1/_|0&zPwP,(W2G>9%Q)wAK2Yx~v-w5fy^Inq )uts?qQ3`8PnAK,vShQpXxT&x. Is this correct? Model Predictive Control for Doubly-Fed Induction Generators and Three-Phase Power Converters describes the application of model predictive control techniques with modulator and finite control sets to squirrel cage induction motor and in doubly-fed induction generators using field orientation control techniques as both current control and direct power control. . Grid Connected Unsymmetrical Two-Phase Induction Generator System Using Time-Based Unbalanced Space Vector PWM and Adaptive Hysteresis Band Current Control Abstract. A capacitor bank can be connected across the stator terminals to supply reactive power to the machine as well as to the load. Does subclassing int to forbid negative integers break Liskov Substitution Principle? These machines can be operated in two modes [2] [3] [4] [5] 1) Grid Connected Mode: In this mode, the induction machine is connected with the power supply line and machine is made to run. Copyright 2022 GoHz.com. YA $rtyEhjTq#KYW8I8GJ~:yl]>Ge'W^ DQ|a. *EbdE@O,WEiEUV 2lziPMm*:T4r\HoVq!eH ueW!3qD, The grid system can exports or I connect 9 lead 3 phase motor with capacitors for operate as generator. I assumed the rotor field would align with the stator field and would therefore induce currents in those stator windings with the most current and therefore the strongest magnetic field. ~L`]0%e/y 7iC"@! `-,&@RqXhJASc[}/WU gL)98OpZO+z\*X?-3ubsH B Gross Vehicle Weight: 24,000 lb. Fig. This paper presents performance analysis of a single-phase grid conneted unsymmetrical two-phase induction generator. Calculate the active and reactive power of the connected load after field increase in synchronous generator. Can someone verify my understanding of induction motors? Download scientific diagram | The description of the non-grid-connected hydrogen production and logistics of floating offshore wind power. It stays in sync and delivers energy as long as it is driven at an rpm higher than its synchronous speed. 6-8 shows the simulation results of the system model with capacitor bank and SVC, where the effect of grid fault on rotor speed, electromagnetic torque and system voltage has been shown w.r.t time. Is this meat that I was told was brisket in Barcelona the same as U.S. brisket? . analysis of a synchronverter-based system conducted through the bifurcation theory to expose its stability regions in a grid-connected configuration with an aggregate . Sync speed is 120 X frequency / number of poles thus a 4 pole machine on 50 Hz power supply must be driven at 1500 plus 30 rpm min and 75 rpm ideal. 2 0 obj It is used for a small range of wind speed. Large-scale wind farms connect to the grid and deliver electrical energy to the load center. Why doesn't this unzip all my files in a given directory? Asking for help, clarification, or responding to other answers. Sorry, preview is currently unavailable. 5wdbRTUVVqk[LRRd9&2l&O:2Vyf`m0Myh:LJ"MM>>e||9~UE#'?K& g/DEX[2Ymct Bm|@^c9RK(,3U9gYgoYQE{U*k^}j3j@1u6yQb%Cewme5UA\kRBCT6 O$> )MOh"(%{ :0SA}D=Fz>t(Cu&(Cs2(R !1Kj:3I ;1H\{"k:VkD8:q (PCC) caused by the doubly fed induction generator, a closedloop control method of the static synchronous compensator (STATCOM) is proposed, through which proportional integral (PI . A single parameter based fuzzy model for controlling the Doubly Fed Induction Generator (DFIG) based Wind Energy Conversion System (WECS) to operate in islanded mode is discussed in this paper. 4 0 obj The generator is 0.7 m long. The control scheme for both RSC and SSC employ cascaded control loops: Outer . You can find a simple explanation of what an induction generator can do. The speed range of the turbine is dictated by the torque vs. speed characteristic of the induction generator. The grid system can exports or imports the active and reactive power (P s, Q s). This may be an invalid assumption. The induction generator has a squirrel cage rotor which draws magnetizing current from the stator giving rise to a high reactive power demand when fluxing, as when the generator circuit breaker is first closed. Download : Download high-res image (157KB) PSO based controlled six-phase grid connected induction generator for wind energy generation Abstract: This paper deals a detailed performance investigation of asymmetrical six-phase grid connected induction generator (GCIG) in two proposed configurations in variable speed operation. Use MathJax to format equations. If it is feeding a 50 Hz power supply it must be driven 2% to 5% above ts sync speed. For sudden changes in wind speed, the mechanical inertia of the drive train will limit the rate of change in electrical output. Generally, there are two types of induction generators widely used in wind power systems - Squirrel-Cage Induction Generator (SCIG) and Doubly-Fed Induction Generator (DFIG). Sleeps: 9. To learn more, see our tips on writing great answers. At 2.0% slip, reactive power consumption grows to 900 kVAR. What is the rationale of climate activists pouring soup on Van Gogh paintings of sunflowers? It he equivalent circuit, the current is produced by a negative resistance in the rotor circuit. You can find a simple explanation of what an induction generator can do. DFIG System. 3 0 obj rev2022.11.7.43014. Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. the rotor speed is slightly ahead of the rotating flux in the stator winding. Will it have a bad influence on getting a student visa? How do I prevent the generator from motoring when the wind speed is to low to drive the generator at or above above sync speed. GRID CONNECTED DOUBLY FED INDUCTION GENERATOR FOR WIND ENERGY CONVERSION SYSTEM INTEGRATED WITH PV MODULE 1 K. KALYANI , Pg Student 2 Mr. P. SAI NIRANJAN KUMAR , Assistant Professor Department of Electrical and Electronics Engineering G.NARAYANAMMA INSTITUTE OF TECHNOLOGY & SCIENCE(For women)Hyderabad ENERGY CONVERSION SYSTEM INTEGRATED WITH PV Type 2: It consists of an AC-DC-AC converter in addition to the induction generator before being connected to the power grid. Yet this cannot be true if this current is supposed to be in phase with the source voltage, as the above answer suggested. If the grid goes down, the generator loses its field and stops so that it cannot send . The production of low-carbon gaseous fuels from biomass has the potential to reduce greenhouse gas emissions and promote energy sustainability, stability and affordability around the world. Does a grid-connected induction generator create phase difference between the grid voltage and generated current? Grids that are being fed by large number of wind generators are already finding that the problems are becoming intolerable. Nowadays DFIGs are more focused in the wind energy conversion systems due to its own advantages. It is simultaneously a lagging power-factor load and a unity power factor supply." Power flow will be balanced with its AVR & generator control. Wind turbines with squirrel-cage induction generators connected directly to the line are the simplest electrically. Academia.edu uses cookies to personalize content, tailor ads and improve the user experience. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Who is "Mar" ("The Master") in the Bavli? Dynamic characteristics of the studied induction generators under a severe torque disturbance and sudden disconnection from the utility grid are studied in detail. endobj Engine Manufacturer: Ford. Grid-connected Wind Turbine (phasor type) Induction Generator using MATLAB/SIMULINK Principle of operation: An induction generator produces electrical power when its rotor is turned faster than the synchronous speed. A coupling inductor is connected between the grid and converter which filters the high frequency ripples generated from converter switching. 12. Control of Grid Side Converter for Grid Connected Six Phase Induction Generator Power Quality Enhancement Authors: Mohit Bajaj National Institute of Technology Delhi India . An Induction Machine sometimes is used as a generator. % Thor Motor Coach Miramar Class A gas motorhome 37.1 highlights: Triple Slides Tilt-A-View Inclining King Bed . This facilitates them to be used in wind generating systems. I don't understand the use of diodes in this diagram.