Generator Controller Reverse Engineering

Boise State University Department of Electrical and Computer Engineering

EE 482, Senior Design Project Spring 2007

Lewandowski Wind Farm Project

Final Report

Date Due: 04/30/07 Date Submitted: 04/30/07

Instructor: Robert Hay Group Members: Chris Raymes Advisor: Dr. Ahmed-Zaid Mike McKee Sponsor: G3, LLC Team Number: 4

EE 482 Technical Document Spring 2007

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TABLE OF CONTENTS 1. ABSTRACT......................................................................................................................... 3

2. INTRODUCTION ................................................................................................................ 4

3. PROBLEMS AND APPROACHES...................................................................................... 4

4. AUTO SYNCHRONOUS CONTROLLER (ASC) THEORY ................................................. 4

4.1 System Overview......................................................................................................... 4

4.2 System Components.................................................................................................... 5

4.3 Operational Theory ...................................................................................................... 6

4.4 Matlab/Simulink Model ................................................................................................10

5. LEWANDOWSKI WIND FARM ASC HARDWARE CONFIGURATION..............................11

5.1 Site Overview..............................................................................................................11

5.2 FCOG-6100 Firing Board with Gamma Regulator Board.............................................11

5.3 Silicon Controlled Rectifiers ........................................................................................13

5.4 Transient Surge Suppression Board ...........................................................................13

6. FUNCTIONAL LABORATORY MODEL .............................................................................14

6.1 System Overview........................................................................................................14

6.2 System Hardware Configuration .................................................................................14

6.3 Basic Operational Theory and Instructions..................................................................15

6.4 Initial Testing Results and Current Functional Status ..................................................18

7. FUTURE RESEARCH AND TESTING...............................................................................19

8. CONCLUSION...................................................................................................................20

9. AKNOWLEDGEMENTS.....................................................................................................20

10. APPENDICIES ...............................................................................................................21

10.1 APPENDIX A – ASC CONNECTION DIAGRAM .....................................................21

10.2 APPENDIX B – FCOG6100 FIRING BOARD DETAILS...........................................22

10.3 APPENDIX D – LABORATORY MODEL CONNECTION DIAGRAM.......................25

10.4 APPENDIX E – EAGLE SCHEMATIC/LAYOUT FOR SCR BOARD........................27

10.5 APPENDIX F – REFERENCES...............................................................................29


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1. ABSTRACT

As the need for environmentally sustainable energy sources become more important, wind energy has developed into an attractive supplement to conventional technologies. The focus of the project is to develop a comprehensive understanding of the functionality of the main generator and associated controls common to all three wind turbines at the Lewandowski wind farm. The primary intent of the project is to help expand a research based relationship between Boise State University and the wind farm owners. The project was divided into three main tasks. The initial task involved extensive research into the current functionality and hardware configurations of the wind turbine systems. This was accomplished through site visits, communication with the owners, and researching the details of the hardware components presently used in the systems. The second task involved the construction of a scaled system model in a laboratory environment. The final task was the development this detailed technical document to be provided to the university and the owners documenting the findings of the project team. The Lewandowski wind farm uses the ENERPRO Auto Synchronous Controller (ASC) control system1 to coordinate generator tie-in/off of the utility grid. The ASC control system takes advantage of the tendency of induction generators to self-excite when driven above synchronous speed and is based on the concept of utilizing a fixed gate delay (firing angle) thyristor controller; a concept originally developed at the National Aeronautics and Space Administration (NASA). The underlying theory is related to the relationship between an induction machine’s power factor and slip interacting with an opposing thyristor pair fired at a large fixed firing angle2. ENERPRO literature suggests that the ASC control system provides smooth ramp-up/down transitions, improved generator efficiency, and reduces inrush current from typical values of 12.0 times the rated generator current for conventional contactor control to 2.0 times the rated generator operating current3. This document and the related research will create a foundation for further research and testing of the performance and characteristics of the ENERPRO ASC system as implemented at the Lewandowski Wind Farm.


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2. INTRODUCTION

This document will first describe the scope of the Lewandowski wind farm project and the approaches taken by the project team to solve the problems presented in the scope. Secondly, the document will describe in detail the functionality of the ENERPRO Auto Synchronous Controller (ASC) control system including an overview of the ASC control system, a description of all ASC control system hardware components, and the operational theory behind the ASC control system. Third, the document will describe the ASC control system hardware configuration as implemented at the Lewandowski wind farm. Fourth, the document will explain in detail the ASC laboratory system model as built by the project team including a system overview, system hardware configuration, operational theory and instructions as well as system testing and results. Next, the document will suggest future research that the project team feels is important for expanding the understanding of the ASC system. Finally, the document will conclude with a review of the project team’s accomplishments with regards to the project scope. 3. PROBLEMS AND APPROACHES

The Lewandowski wind farm consists of three wind turbines built by the late Robert Lewandowski on land located southeast of Boise. Mr. Lewandowski passed away July of 2005 and left very little documentation regarding the details of his three wind turbines. On April 28, 2006, the newly formed corporation G3, LLC purchased the wind farm4. The goal of the project is to deliver this technical document to Boise State University and G3, LLC explaining in detail how the main 108 kW generator control system works as implemented in each turbine at the wind farm in order to advance further research. Two approaches were used to create this document:

• Research as much of the existing system components as possible through site visits, hardware manufacturer communication and literature, journal articles, and patents.

• Construct a model of the system using similar hardware scaled to run in a laboratory

environment to acquire a better understanding of the system such that the hardware configuration can be easily integrated into future research.

4. AUTO SYNCHRONOUS CONTROLLER (ASC) THEORY

4.1 System Overview

The Auto Synchronous Controller (ASC) is a wind turbine induction generator connect/disconnect controller that utilizes the interaction of thyristors/silicon controlled rectifiers (SCR’s) and generator slip (difference between the synchronous speed and the operating speed of the generator) to coordinate generator tie-in/off to the utility grid. The system is referred to as an Auto Synchronous Controller because the connect/disconnect operation occurs automatically as the generator speed rises above and falls below synchronous, where synchronous speed is the threshold below which the induction machine performs as a motor (positive slip, S) and above which the machine functions as a generator (negative slip, S)5. The ASC control system is enabled at 98% of the machine’s synchronous speed by a shaft speed limit switch. When the system is enabled, a bias of approximately 25% of the rated AC utility mains voltage is applied to the generator stator windings by firing the thyristors at an angle


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of greater than 120°, thus pre-biasing the generator with reduced motoring torque. As the generator shaft speed exceeds the machine’s synchronous speed by a typical value of 0.5%, the generator’s power factor angle (difference between the voltage and current angles) converges on the thyristor firing angle forcing the thyristors into full conduction and bringing the generator online with full utility mains voltage applied to the stator windings. If the shaft speed drops below the generator’s synchronous speed, the system automatically reverts to the pre-bias state to minimize motoring. When the shaft speed falls below the 98% speed switch threshold, the pre-bias is removed from the stator windings and the system shuts down. According to literature provided by ENERPRO, Inc. the ASC control system provides smooth ramp-up/down transitions, reducing inrush current from typical values of 12.0 times the rated generator current for conventional contactor control to 2.0 times the rated generator operating current6. In addition to reduced inrush current at start-up, ENERPRO literature maintains that the ASC control system improves the efficiency of generators used in wind turbine applications. Wind powered generators are sized to operate at typical wind velocities of 50 mph, and therefore the generators are substantially oversized for the more typical values of 10-25 mph generally encountered in the wind farm environment. Consequently wind generators are somewhat inefficient when operating in light winds. ENERPRO literature claims that the ASC control system applies lower than rated voltage to the generator in light winds, effectively reducing its internal electrical losses and increasing its net power output7.

4.2 System Components

As shown in Figure 1, the ASC control system consists of a thyristor switching assembly, a thyristor firing board, a gamma regulator board that provides feedback control for the thyristor firing angle, and transient surge suppression circuits that protect the thyristors from over-voltage during switching.


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Thyristor Array

FCOG-6100 Firing Board

GRB-1 Gamma

Regulator Board

Hold-off angle, γ

New firing angle, α

Gate Pulses

Line Side

Voltages

Load Side

Voltages

Status

Board Power 120V AC

Manual/Motor

Pre-Synchronous Enable

480V AC Protected Grid Connection

108 kW Generator

Connection

Transient Surge

Suppression Board

Line Side

Voltages

Load Side

Voltages

Auto Synchronous

Controller

Figure 1: Block Diagram Showing ASC System Hardware Components

4.3 Operational Theory

What follows is a summary of the operational theory for the ENERPRO ASC control system as understood by the project team. These results were acquired through comprehensive research of the existing system components by means of a site visit and hardware manufacturer communication, in addition to literature resources including journal articles and patents. The ASC control system takes advantage of the tendency of the generator to self-excite when driven above synchronous speed. The concept of induction generator self-excitation with a fixed gate delay angle thyristor controller is based on a patent by National Aeronautics and Space Administration (NASA) engineer Frank J. Nola8 of which ENERPRO, Inc. of Goleta, CA is the sole licensee. Although the physical ASC control system does not explicitly utilize a fixed gate delay (firing angle), the system’s fundamental operational theory is directly related to this concept. The underlying theory is based on the relationship between an induction machine’s power factor and slip interacting with an opposing thyristor pair fired at a large fixed firing angle. The opposing


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thyristor pair is modeled as a slip dependent variable inductance according to studies found in Auto Synchronous Controller Operation: Theory and Test Results by Frank J. Bourbeau of ENERPRO, Inc. The ENERPRO literature regarding this theory then uses a fixed firing angle (α) of 140° applied to the gate of an opposing thyristor pair connected in series with a single phase equivalent circuit of an induction machine to model the ASC control system as shown in Figure 2.

Figure 2 - single phase equivalent circuit

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For the ASC and induction machine equivalent circuit shown in Figure 3 with a positive slip value of 0.5 %, the machine’s power factor angle (Ф) is confined to quadrant I (i.e. 0° ≤ Ф ≤ 90°) due to a positive rotor resistance parameter (inversely proportional to slip) and therefore has not converged on the thyristor firing angle when fixed at 140°. In this ideal situation the thyristors are open circuited and no voltage is applied to the induction machine.

Figure 3 - speed = 1791 rpm, S = .005, Ф = 80°

α =140°, thyristors act as an open circuit10


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For the ASC and induction machine equivalent circuit shown in Figure 4 with a negative slip value of -1.5 %, the rotor resistance parameter is negative (machine is acting as a generator) and therefore the machine’s power factor angle moves to quadrant II (i.e. 90° ≤ Ф ≤ 180°) and eventually converges on the fixed thyristor firing angle at 140°. As the generator’s power factor angle converges on the fixed firing angle the thyristors become short circuited and the voltage applied to the generator approaches the utility mains voltage.

Figure 4- speed = 1827 rpm, S = -.015, Ф = 140° α = 140°, thyristors become short circuit

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Based on the ASC and induction machine equivalent circuit, the voltage-slip profile for the induction machine shown in Figure 5 indicates that the potential across the stator windings increases linearly from a slip value of 0.5% to a slightly negative slip value and then increases exponentially until the full system voltage is placed across the stator windings at a slip value of approximately -1.5%.

Figure 5 – Generator (Eg) voltage versus Slip (S)

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The physical ASC control system functionality is based on the phenomenon of induction generator self-excitation with a fixed gate delay angle thyristor controller with several important differences. The system is designed to enable with a slip of 2% (rotor RPM 98% of synchronous). Based on the profile indicated in Figure 5, it is reasonable to assume that a slip of 2% would yield zero generator voltage. However, a potentiometer on the gamma regulator board allows the ASC to be field configured such that a pre-bias equal to 25% of rated system voltage is applied to the machine at 2% slip. This pre-bias state excites the machine with negligible motoring losses to aid in full excitation when the slip goes negative and the generator power factor angle Ф converges on the thyristor firing angle α. Another important difference is related to stability augmentation and efficiency. According to Auto Synchronous Controller Operation: Theory and Test Results by Frank J. Bourbeau, ENERPRO, Inc. the fixed firing angle control method proved to be unstable in certain wind conditions. To compensate, feedback control is implemented to increase the firing angle as the generator voltage increases. ENERPRO literature suggests that the feedback control also allows the ASC to apply a lower than rated voltage to the generator in light winds, effectively converting the over-sized generator into an electrically smaller machine, reducing its internal electrical losses and increasing power output. To implement this control, ENERPRO uses a thyristor firing board (FCOG6100), a gamma regulator board (GRB-1), and a transient surge suppression board (TSB-3). The firing board supplies the gate pulses to a thyristor array enabling the system. The thyristor gating is enabled by speed switch contacts connected to the firing board. The system is enabled at 98% of the generator’s synchronous speed. Firing angle modulation is made possible by monitoring the hold-off angle γ, where γ is equal to half of the difference between the thyristor firing angle α and the generator power factor angle Ф. The gamma regulator board measures the hold-off angle by monitoring the thyristor cathode voltages passed through the firing board thyristor connections.


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4.4 Matlab/Simulink Model

MATLAB with Simulink proved useful in verifying details regarding ASC operation. The single phase model shown in Figure 6 was used to simulate the pre-bias state when the ASC has just been enabled at 98% of synchronous speed. It was found that a large firing angle of 149° setup a pre-bias state of 25% of rated voltage confirming ENERPRO theory and literature.

Single Phase Model of an Induction Machine with SCR Control (Fixed Firing Angle)

Xp = primary leakage inductanceXm = magnetizing inductanceXs = secondary leakage inductanceR = rotor resistance S = slip = 1 - N/1800

Assumptions:synchronous speed: 1800rpmfiring angle (fixed): 149 degreessystem voltage: 480Vrms L-Lpre-bias generator voltage: 120Vrms L-L

1764

shaft speed

Xs = 1e-3Xp = 1e-3

Xm = 1e-3

v+-

Vload

gm

ak

Thyristor1

g m

a k

Thyristor

Scope

signal rms

RMS

R +-

Va

riab

le R

esis

tor

R/S, R=1

N Rfcn

R(s)Pulse

Generator

i+

-

Is

120

Display

480Vrms

Figure 6: Simulink ASC and Induction Machine Single Phase Equivalent Model


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5. LEWANDOWSKI WIND FARM ASC HARDWARE CONFIGURATION

5.1 Site Overview

The site overview will provide a synopsis of the ASC control system configurations for the control systems common to each of three main 108 kW generators as implemented at the Lewandowski wind farm. Further specification and configuration detail regarding each of the ASC control system components will be discussed in Sections 5.2, 5.3, and 5.4. A very close approximation to what is believed to be implemented on site is shown in an ENERPRO drawing in Appendix A. Similar to this drawing, each of the three main 108 kW generator systems utilizes a 480V AC three phase connection to the utility grid and a 120V AC single phase interface to the ASC control system. Like the field configuration, the ENERPRO drawing in Appendix A shows an interposing relay connection (enable relay K1) used to enable the ASC system at 98% of synchronous speed. As shown in Figure 7 each of the turbine control systems utilizes a high speed counter process indicator connected to a proximity sensor, as shown in Figure 8 to monitor rotor speed. The high speed counter process indicator has a programmable high or low limit (depending on internal and interposing relay configuration, i.e. N.O. or N.C. contacts) to allow system enabling when rotor speed reaches 98% of the machine’s synchronous speed. It is important to note that on site a parallel capacitive load is connected to the generator using a motor contactor. It is not clear how this affects the system operation and when the capacitive load is connected on site; this will be discussed in Section 7.

Figure 7: High Speed Counter Process

Indicator

Figure 8: Shaft Proximity Sensor

5.2 FCOG-6100 Firing Board with Gamma Regulator Board

As per the ENERPRO ordering guide for the three-phase thyristor firing board including GRB-1, the on site component specific part number is: FCOG-6100-02-0-60-1-48-2-1.13 The specific part number for the firing board contains a “1” in the field “used with regulator.” This field specifies a firing board with J6 populated with a connection header used for interface with a regulator board; on site a gamma regulator board is used.14 The specific part number for the regulator board is: GRB-1A.


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Unlike the board used to construct the laboratory model, to be presented in Section 6, each control system firing board used on site utilizes solder bridges instead of a DIP switch package to configure the PP1 header as shown in Figure 9. These settings are used to provide phase reference and gate pulse profile selection. Table 1 gives the PP1 header settings as field configured for the firing board as shown in Figure 915. Table 1: PP1 Header Settings as Field Configured for the FCOG-6100 Firing Board

PP1 Position 1 2 3 4 5 6 7 8 Setting Open Open Open Close Close Close Open Close

PP1 positions 1, 2, 3, 4, 5, and 6 are used to program the systems PLL (phase locked loop) settings with respect to the systems phase reference. The settings in Table 1 yield a configuration suitable for AC controllers with high power factor loads. PP1 positions 7 and 8 are used to program the SCR’s gate pulse profile. The settings in Table 1 yield a “mode 1” profile such that the firing board delivers 120° bursts of 128 pulses (23,040 Hz carrier frequency) to the SCR’s16. The gamma regulator board incorporates a potentiometer (R1) to adjust the pre-bias voltage for the generator. The potentiometer is to be adjusted to give approximately 120 VRMS line-to-line (25% of rated) generator voltage at zero speed. This measurement must be made with a true RMS reading voltmeter.17

Figure 9: FCOG6100 with GRB-1 Showing Solder Bridges for PP1 Header Settings


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5.3 Silicon Controlled Rectifiers

Two silicon control rectifier (thyristor) packages are used on site manufactured from International Rectifier and POWEREX. The International Rectifier part used on site is known and is: IRKT250-16, however this part number is listed as divested from the manufacturer website and is not available. Each is mounted on the side of the enclosure with a large heat sink perforating through the enclosure, as seen in Figure 10. Three thyristor devices are used in each control system, each containing an opposing thyristor pair. The two gate drive signals and cathode feedback connections can been seen on each device in Figure 10 as a small connector with a red and white wire on the top of the SCR package (one connector for each internal SCR). The firing board has two connectors, J1 and J2, used for SCR gating and feedback. The FCOG6100 schematic, shown in Appendix B, details the connection information required for wiring the firing board to the SCR devices.18

Figure 10: SCR Packages

5.4 Transient Surge Suppression Board

The exact part number for the transient surge suppression or snubber board used on site, as shown in Figure 11, is not known. If the snubber board were to be replaced, the ENERPRO equivalent component specific part number is: TSB-3B-550-30-35-20-0 Rev B. This information was provided by communications with Engineering Sales Representative Patrick Marshall of ENERPRO, Inc. given on the CD Appendix. The transient surge suppression board (TSB) is designed to protect the SCR devices from over-voltage during switching. As detailed in Appendix A, each SCR paired device has two connections to the snubber board, one on the line side of the SCR device and one on the load side. The phase A SCR device is interfaced to the transient surge suppression board at TSB header J3, pins 1 and 3; the phase B SCR device is interfaced to the snubber board at TSB header J2, pins 1 and 3; and the phase C SCR device is interfaced to the transient surge suppression board at TSB header J1, pins 1 and 3.


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Figure 11: TSB or Snubber Board

6. FUNCTIONAL LABORATORY MODEL

6.1 System Overview

The project team constructed a scaled functional ASC model intended to be used as a research tool to assist this project and to be provided as a resource for future wind energy projects at Boise State University. The system uses similar ASC components to those used on site, but designed to operate using 208V AC three phase versus 480V AC, as used on site. The model is designed to interface with the Lab-Volt Industrial Machine Training System used at Boise State University with a 0.25 Hp induction machine (wound rotor, or squirrel cage). A prime mover is used to apply wind torque to the induction machine. This section will discuss the hardware configuration, operational theory, and any useful results found due to laboratory testing.

6.2 System Hardware Configuration

An AutoCAD drawing of the ASC laboratory model schematic is shown in Appendix D. Figure 12 shows the physical wiring of the laboratory model including terminal blocks, SCR board, FCOG6100 firing board with GRB-1; the transient surge suppression board is mounted directly under the firing board and is not readily visible in Figure 12, however the connections to TSB headers J1, J2 and J3 can be seen in Figure 12 as the three sets of two red conductors directly under the FCOG6100 J1 and J2 headers (two sets of six blue conductors marked “J1” and “J2”). The two source voltage inputs from the Lab-Volt power supply to the firing board can be seen in Figure 12 as the two red conductors just above the transformer at FCOG6100 header J4 pins 1 and 5; this configuration yields the high voltage input option (208V) to the firing board. The ASC control wiring can be seen in Figure 12 as the set of seven blue conductors below and to the left of the transformer at FCOG6100 header J3; the firing board is also bonded to the laboratory model enclosure through FCOG6100 header J3 at pin 8.


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Figure 12: Scaled ASC Laboratory Model

The SCR board can be seen in Figure 12 as the printed circuit board (PCB) just to the left of the firing board, where the six black devices are the heat sinks associated with each SCR. The SCR printed circuit board was designed and assembled by the project team. Schematic and layout information can be found in Appendix E. The SCR printed circuit board used in the laboratory model was constructed using six (6) TO-220AB SCR packages (Digikey part number: 25TTS08-ND), six (6) 5W heat sinks (Digikey part number: HS104-2-ND), six (6) heat sink pads (Digikey part number: BER221-ND), and two (2) 12 position 5MM terminal blocks (Digikey part number: 277-1026-ND). The PCB design shown in Appendix E, including schematic and layout, was completed using Eagle computer aided design (CAD) software19.

6.3 Basic Operational Theory and Instructions

Four critical components are needed for laboratory operation: Lab-Volt power supply, Lab-Volt prime mover / dynamometer, Lab-Volt induction machine, and the ASC system. These are shown in Figure 13. The ASC can be seen in the lower left corner. The prime mover / dynamometer can be seen directly to the right of the ASC, and the induction machine can be seen adjacent to the prime mover / dynamometer in the lower right hand corner. The power supply can be seen directly above the ASC system. Also, directly above the induction machine, a bi-directional Watt / VAR meter will be useful for power monitoring.


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Figure 13: ASC, Power Supply, Prime Mover / Dynamometer, Wound Rotor Induction Machine,

and Watt / VAR Meter

The scaled model is designed to use a 0.25 HP wye-connected wound rotor or squirrel cage induction machine to replicate the main generators used on site and a 208V AC three phase connection to the laboratory power supply. A 120/208V transformer on the firing board provides the 120V AC single phase interface to the ASC control system. The prime mover, used to simulate wind torque, requires a 0-120 V DC speed control input and 120 V AC electronics control input. The bi-directional Watt / VAR meter is used for power monitoring. The overall laboratory system hardware configuration is shown in Figure 13. Similar to the scaled laboratory model as constructed by the project team, the ENERPRO drawing in Appendix A shows an interposing relay connection (enable relay K1) used to enable the ASC system at 98% of synchronous speed. Unlike the site-configured ASC control systems the laboratory model uses a manual system enable. The toggle switch labeled “system enable” on the ASC model face plate, shown in Figure 14, will function as the manual system enable when the prime mover reaches 1764 RPM or 98% of the induction machine’s synchronous speed.


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Figure 14: ASC Model Face Plate

The overall scaled model hardware setup configuration is shown in Figure 15. To initially setup and operate the system, the system must be connected as shown in Figure 15, with the exception of the optional encoder circuit. If the system is connected and preconfigured properly (i.e. DIP switch positions) then it is possible to set the pre-bias potentiometer (R1) on the gamma regulator board. While applying the 208V AC three phase to the input of the ASC and manually enabling the ASC via the face plate toggle switch with the induction machine at zero speed and no load torque applied, the potentiometer is to be adjusted until 25% of 208V (52V) line-to-line is read across the generator connection with a true RMS voltmeter. After setting the pre-bias voltage, the system is ready for basic operation. To operate the system, use the variable DC supply to set the prime mover speed at 98% of synchronous speed (1764 RPM). Four-pole induction machines are used, and therefore have a synchronous speed of 1800 RPM. When the speed is 98% percent of synchronous speed, the ASC should be manually enabled. In theory, it should be possible to manually increase the prime mover speed slightly above synchronous and use the Watt / VAR meter to observe power generation. As shown in Appendix A, the ASC control system also has a motoring function enabled through an external motoring contact. Some ENERPRO literature suggests that the motoring function requires two resistors, one of which is 2 kΩ, and the other to be selected to provide the desired output current with the motor switch closed. The system was designed to accommodate these resistors. The motoring function was not used by the project team in its testing; any future research involving the ASC motoring function may require additional information and calculation when determining resistor values.


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ASC System

DC Speed

Control

Generator Excitation

Voltage / Generated

Power

Laboratory

Configuration

Lab-Volt Power Supply, Using

Fixed 208V AC 3Ф Line-to-Line,

Variable 0-120V DC 8A

Watt / VAR

Instrumentation

Induction Machine

Generator Excitation

Voltage / Generated

Power

Applied Torque

Simulating

Wind

208V AC 3Ф

Line-to-Line

Lab-Volt Primemover / Dynamometer, functioning as a primemover indicating shaft

speed controlled via variable DC voltage from Lab-Volt Power Supply

Manual Enable

Manual

Motoring

Enable Status

Optional High Speed Counter with a

Quadrature Input with a

Programmable Limit

A & B

Encoder

Signals

Relay Connection

Replacing

Manual Enable

Figure 15: Laboratory Operational Configuration with Future Encoder Feedback Option

6.4 Initial Testing Results and Current Functional Status

The overall scaled model hardware underwent its initial test at the end of the project with assistance from the project advisor. Although the system is not ready for full operation, the team was very pleased with the results. All the team’s wiring, design and assembly proved to be correct thanks to repeated checking and verification of the design. The ENERPRO hardware was energized without any faults. The SCR board, designed by the team, functioned correctly without any signs of excessive heating. The system wiring proved to be correct. The majority of the testing was focused on setting the pre-bias voltage on the generator by adjusting the potentiometer on the gamma regulator board. While 208V was applied to the ASC and the generator was connected to the ASC output, the system was enabled at zero speed (no prime mover speed applied). Potentiometer adjustments directly and significantly changed the generator voltage showing that the firing angle was changing. The voltage however was not adjustable down to the 25% (adjusted to about 140V) of rated line-to-line voltage. The team believes this is due to the small size and characteristics of the unloaded generator in the lab, versus a typical generator used in a power generation application.


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The team believes it will take a significant amount of time to fully research the characteristics of the induction machine used in the lab tests; specifically its power factor curve as a function of slip. Referencing this information with future discussions with ENERPRO regarding the range and capabilities of the gamma regulator board should yield successful results. The project team has paved the path for these results by contacting the founder and president of ENERPRO, and inventor of the ASC control system, Frank J. Bourbeau. According to Mr. Bourbeau, the 0.25 HP machine will not be large enough to work as a scale model induction generator. The appropriate voltage versus torque response will not be achieved because the power factor and efficiency of the 0.25 HP induction machine are too small. As per Mr. Bourbeau, the induction machine needs to at minimum 5 kW, and if possible a high efficiency design. Future research will have to address these issues and concerns. Any information received after the completion of this project will be forwarded to the project advisor. 7. FUTURE RESEARCH AND TESTING

After accounting for the induction machine sizing issue, future research and several physical tests can be performed using the laboratory model. Some of the tests and research the project team has considered are bulleted below:

• Observe the firing angle and power factor during various slip configurations.

• Test the system during very high speeds (simulating high wind) observing power factor, power factor and firing angles.

• Test the system during slow speeds in order to verify ENERPRO’s efficiency claims regarding generator de-rating.

• Test the effects of pre-bias voltage adjustments above and below 25% of rated voltage.

• Test the effects of enabling below or above the 98% of synchronous threshold.

• Observe and record the generator cut-in current profile in the lab under different conditions.

• Compare performance and research with other methods of control (contactor, traditional soft-start, other wind controllers, etc.)

• Examine potential improvements gained by utilizing a programmable logic controller in addition to the current ASC system.

• Test the effects of a parallel capacitive load on ASC operation to better understand the on site configuration. As seen in Figure 16, Mr. Lewandowski utilized large capacitive loads in parallel with the generator. This is assumed to affect power factor and consequently the operational characteristics of the ASC system. This should be researched and tested in the laboratory.

Figure 16: Capacitive Load as Implemented On Site


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8. CONCLUSION

The project team has made significant progress in its understanding of the ASC system as pertaining to the Lewandowski wind farm as well as laying the foundation for many laboratory research opportunities. The team expects an improved understanding of the ASC system for researchers at Boise State University and G3, LLC through its project efforts. As with most research, this endeavor has revealed many questions regarding ASC operation as well as significantly improving the understanding of the system. The team hopes that this work will lead the way to answering some of the questions in Section 6, and others not conceived by the research team, via future Senior Design and research projects at Boise State University. The team feels that the project was very successful and its completion satisfies all scoped items. 9. AKNOWLEDGEMENTS

The project team is appreciative for the efforts of the following individuals:

• Saul Rivera and Tony Limjoco, Design/ Engineering Managers with ENERPRO, Inc for the technical information provided regarding ASC theory and operation

• Frank J. Bourbeau, Founder and President, ENERPRO, Inc.

• Ty Nelson, Sales Representative with Graybar Electric, Boise who provided the team with terminal blocks and terminal block numbers

• Dr. S.M. Loo and his research associates for their support in producing the SCR board for the ASC laboratory model

• Project advisor Dr. Said Ahmed-Zaid

• Project sponsor Todd Haynes of G3, LLC


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10. APPENDICIES

10.1 APPENDIX A – ASC CONNECTION DIAGRAM


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10.2 APPENDIX B – FCOG6100 FIRING BOARD DETAILS


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24


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10.3 APPENDIX D – LABORATORY MODEL CONNECTION DIAGRAM


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10.4 APPENDIX E – EAGLE SCHEMATIC/LAYOUT FOR SCR BOARD

PCB Schematic:

PCB Bottom Layer:


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PCB Top Layer:

PCB Component Placement (Top):


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10.5 APPENDIX F – REFERENCES

1 www.enerpro-inc.com

2 Auto Synchronous Controller Operation: Theory and Test Results, Frank J. Bourbeau, ENERPRO, Inc,

September, 1991 3 Auto Synchronous Controller Operation: Theory and Test Results, Frank J. Bourbeau, ENERPRO, Inc,

September, 1991 4 IDWRreport_InhouseVersion, G3, LLC

5 Grid Connection with Auto Synchronous Controller, Frank J. Bourbeau, ENERPRO, Inc, October, 1987



8 Power Factor Control System for AC Induction Motors, Frank J. Nola, United States Patent No.

4,266,177, May 5, 1981 9 Auto Synchronous Controller Operation: Theory and Test Results, Frank J. Bourbeau, ENERPRO, Inc,

September, 1991 10

Auto Synchronous Controller Operation: Theory and Test Results, Frank J. Bourbeau, ENERPRO, Inc, September, 1991 11



Three-Phase Thyristor Firing Board, Ordering Brochure, ENERPRO, Inc. 1994 14

Three-Phase Thyristor Firing Board, Ordering Brochure, ENERPRO, Inc. 1994 15 General Purpose 3Ø Firing Circuit, Dwg. No. E128 Sheets 1 and 2, ENERPRO, Inc. December, 18

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1991 16

Operating Manual for a 6-SCR General Purpose Gate Firing Board, Part No. FCOG6100 REV. J, J’, J’’, K, ENERPRO, Inc. October, 1993 17

Connection Diagram: Auto Synchronous Controller, Dwg. No. E497-5, , Inc., September, 24th 1998

18 General Purpose 3Ø Firing Circuit, Dwg. No. E128 Sheets 1 and 2, ENERPRO, Inc. December, 18

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1991 19

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Generator Controller Reverse Engineering

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