Field Flashing Synchronous Generator

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Black Start System for a Synchronous Generator
Sponsor: Schweitzer Engineering Laboratories
Team Name: The Flash
Duration: Fall 2015 - Spring 2016
Faculty Advisor:
Technical Advisor:
Students:
  • Will Parker
  • Bruno Loza
  • Khalid Alotaibi
  • The goal of this project is to create a black start system for a 15-kVA synchronous generator system in the University of Idaho Model Power System Lab. Team members will design the system, simulate using RTDS system modeling, install the system, and then conduct tests. This project is sponsored by Schweitzer Engineering Laboratories and is advised by professors in the University of Idaho electrical engineering department.



    Problem Definition[edit]

    When power goes completely out, it is necessary to excite the fields of power system generators with battery power to re-start the generators before switching back to using generator output power for field excitation; this is known as a black start. We are designing a black start field exciter system for the 15kVA synchronous generator in the Buchanan Engineering Power Lab to be used for research on black start conditions.

    Background[edit]

    When power has been completely or partially lost in a grid, a black start procedure is required to restore generation capabilities. In some cases, diesel generators are used to start the larger main power generators. In the northwest, hydroelectric stations are the common black-start sources. The advantage of hydroelectric power is that the only requirement is that the turbines spin by having the intake gates open and the generator field coils be excited.

    Deliverables[edit]

    • Black Start System for GJL 15 kVA Generator:
      • ABB Field Exciter
      • Battery Bank
      • Exciter Power Supply Transfer Switch
      • Battery Bank
      • Transfer Switch Controller
    • Validation/improvement of existing RTDS model
    • Model of black start on RTDS simulation
    • Documentation of black start system operating procedures for future work

    Specifications[edit]

    Black Start Diagram


    System Process[edit]

    1. Prime mover spins rotor to initiate a black start
    2. Battery bank provides excitation voltage and current directly to generator sufficient power is provided from synchronous generator to run the field exciter
    3. Black start system controls transfer of exciter power supply from batteries to generator power.
    4. Generator reaches rated output power.
    5. ABB field exciter controls excitation in steady state operation


    Specs Table[edit]

    Specific Requirement Description Target Acceptable Performance Final Design
    Size

    The Black Start System should
    take up a minimal amount of space
    in the BEL Power Lab.

    36" x 48" x 36""

    All dimensions
    smaller than Target.

    6” x 12” x 18”
    "Normal"

    Operating Range

    Normal current through
    the transfer switch
    at rated conditions.

    25 Amps DC and AC

    Can sustain 20 Amps or Better

    Switch does not carry full field current.
    Battery connected to field with
    25A rated TE RM8 Relay with 60A surge rating.


    Transfer Switch Control

    Controller determines when generator
    output is sufficient to
    operate the exciter.

    I/O ports capable of driving transfer switch

    command inputs. Communicate with exciter to
    utilize exciter voltage sensors on
    generator output terminals

    I/O ports capable of driving

    transfer switch command inputs.
    Uses separate voltage/current sensors

    Local Manual Control or
    automatic battery disconnect with
    UNITROL 1020 FCB command DIO signal.

    Forcing Output

    The transfer switch must be capable
    of supplying a short term
    "burst" of power to the generator.

    Up to 45 Amp AC or DC
    Lasts more than 10 seconds

    Sustain 45 Amp DC
    for 10 seconds

    Switch does not carry full field current.
    Battery connected to field with
    25A rated TE RM8 Relay with 60A surge rating.

    Exciter DC supply Voltage

    Battery bank voltage supplied
    to exciter during black start

    24 VDC

    Min 18VDC Max 300 VDC

    Experimental data shows
    UNITROL 1020 AUX input powers on at 12.0V.
    Using FIAMM 12V 7Ah sealed lead acid battery

    Display

    The black start system should indicate
    the power source being used
    to power the exciter

    Indicate power source
    record transfer time

    Indicate power source

    Indicates black start active or battery charging

    System Design[edit]

    System Circuit[edit]

    Black Start Circuit

    System Process: Local Control

    1. Prime mover spins rotor to initiate a black start

    2. User turns selector switch to ON position to connect battery to black start system and power on ABB AUX power supply to AVR control system.

    3. User presses momentary button 1 to turn relay on connecting batteries to field windings of generator.

    4. Battery bank provides excitation current directly to generator. Sufficient power is provided from synchronous generator to run the ABB field exciter PWR inputs.

    5. User releases button 2 disconnecting batteries from field.

    6. UNITROL 1020 to starts its excitation current output in soft-start ramp up.

    7. ABB field exciter controls excitation in steady state operation.

    8. User turns selector switch to charge position to connect batteries to charger.

    Design Prototype[edit]

    Front of Prototype Board Front Connections
    2015 FieldFlash Prototype-front.png
    • VBatt+: Positive connection from battery
    • VBatt-: Negative connection from battery
    • Ie+: Positive connection to field windings
    • Ie-: Negative connection to field windings
    • Remote: Available ports for automatic switching from AVR exciter
    Back of Prototype Board Back Description
    2015 FieldFlash Prototype-back.png

    Element details:

    • Resistor: 1.0 Ohm
    • Relay: Electromechanical Relay
    • Switch: Standard mechanical switch

    Final System Design[edit]

    Front of Black-Start board

    2015 FieldFlash FinalPics closeup.jpg

    No Excitation to System

    2015 FieldFlash FinalPics GenBack.jpg

    Attempt to Start Generator With AVR

    2015 FieldFlash FinalPics Back.jpg

    RTDS[edit]

    RTDS Complete System Model
    This model includes

    • Black Start System
      • Dial for switching between system steps
      • Selector switch for system step selection
        • Step 1: No excitation to synchronous generator
        • Step 2: Excitation provided from battery
        • Step 3: Excitation is switched from battery to AVR
    • ABB AVR exciter
    • Dynamic RL Load
    • 3-phase RMS Meter
    • Rotor speed slider
    • Per-unit to SI unit conversion
    2015 FieldFlash RTDS RSCAD.png

    No Excitation to System
    With no excitation provided from the AVR or battery the following changes occur:

    • Total field current (IF) = 0
    • AVR field voltage (Ef) = 0
    • Total field voltage (Ef_total) = 0
    • RMS bus voltage (BusRMS) = 0
    2015 FieldFlash RTDS NoExc.png

    Battery Excitation
    When introducing the battery to the field windings circuit, a field current is then created which then allows the synchronous generator to produce a terminal voltage. The terminal voltage is much less than the rated voltage thus the AVR has to be brought into the system in the next step.

    • Total field current (IF): Ramps up to 0.06-pu
    • AVR field voltage (Ef): irrelevant
    • Total field voltage (Ef_total): Instant step change to 0.4-pu
    • RMS bus voltage (BusRMS) = Ramps up to 40.26-V
    2015 FieldFlash RTDS BattExc.png

    Switch from Battery to AVR Excitation
    With the AVR brought into the system and the battery disconnected, the AVR takes control of the field excitation. The terminal voltage created by the battery is enough to allow the AVR to remain powered while this transition occurs. The total field voltage is now instantly influenced by the AVR which allows the terminal voltage of the synchronous generator to reach the rated voltage (240-V).

    • Total field current (IF): Logarithmic increase to 1.75-pu
    • AVR field voltage (Ef): Exponential increase from 0.915-pu to 1.75-pu
    • Total field voltage (Ef_total): Exponential increase from 0.4-pu to 1.75-pu
    • RMS bus voltage (BusRMS): Ramped increase from 40-V to 240-V
    2015 FieldFlash RTDS AVRExc.png

    Steady-State Operation
    This model includes

    • Total field current (IF) = 1.75-pu
    • AVR field voltage (Ef) = 1.75-pu
    • Total field voltage (Ef_total) = 1.75-pu
    • RMS bus voltage (BusRMS) = 240-V (rated voltage)
    2015 FieldFlash RTDS SS.png

    Project Learning[edit]

    ABB AVR[edit]

    ABB Unitrol AVR

    Planned Tests for Exciter System[edit]

    1. Check that DCH Supervision Alarm works

    Attach UNITROL PRW and Generator monitor inputs to autotransfromer output from lab voltage supply.

    Connect UNITROL field output to dummy RL load simulating motor field windings

    Increase voltage out of autotransformer to simulate generator output ramping up as field current builds.

    Verify that DCH Supervision Alarm bit toggles at expected setpoint

    2. Test field Excitation with 24 VDC source

    Run generator with VFD controlled motor

    Apply 24VDC from power lab DC power supply to field winding circuit to simulate the proposed battery bank. Use power supply current limit to prevent excessive current then remove current limit and test power resistors in series with source to limit current.

    Observe generator output voltage rise time and final value with 24VDC excitation.



    Team Information[edit]

    Team "Flash"
    Picture Biography Discipline
    Will Parker
    2015 FieldFlash Willphoto.jpg
    Will is a senior in electrical engineering from Palouse, Washington. He will be pursuing a masters in electrical engineering at the University of Idaho after graduation. His emphasis has been in power systems and power electronics. When not studying, Will enjoys backpacking, fly fishing, and gardening. Electrical Engineering
    Bruno Loza
    2015 FieldFlash Brunophoto.jpg
    Bruno is a senior studying electrical engineering with an emphasis in power. He was raised in southern Idaho and his hobbies include playing guitar, ultimate Frisbee, and soccer. Electrical Engineering
    Khalid Alotaibi
    2015 FieldFlash Khalidphoto.jpg
    Khalid is an International student who came from Saudi Arabia. He is a senior in electrical engineering and his emphasis is power. In addition, Khalid loves to play and watch soccer. Other hobbies include volleyball, traveling, horse riding and swimming. Electrical Engineering

    Documents Archive[edit]

    System Specifications[edit]

    File:2015 FieldFlash SystemSpecifications.pdf

    Guides[edit]

    File:2015 FieldFlash QuickStartGuide.pdf
    File:2015 FieldFlash RTDSguide.pdf

    Technical Presentation[edit]

    File:2015 FieldFlash TechPres.pdf

    Meeting Minutes[edit]

    File:2015 FieldFlash Minutes 09-14-15.pdf
    File:2015 FieldFlash Minutes 09-15-15.pdf
    File:2015 FieldFlash Minutes 09-21-15.pdf
    File:2015 FieldFlash Minutes 09-28-15.pdf
    File:2015 FieldFlash Minutes 10-05-15.pdf
    File:2015 FieldFlash Minutes 10-12-15.pdf
    File:2015 FieldFlash Minutes 10-26-15.pdf
    File:2015 FieldFlash Minutes 11-06-15.pdf
    File:2015 FieldFlash Minutes 11-09-15.pdf
    File:2015 FieldFlash Minutes 11-16-15.pdf
    File:2015 FieldFlash Minutes 11-30-15.pdf
    File:2015 FieldFlash Minutes 12-07-15.pdf

    File:2015 FieldFlash Minutes 01-28-16.pdf
    File:2015 FieldFlash Minutes 02-04-16.pdf
    File:2015 FieldFlash Minutes 02-11-16.pdf
    File:2015 FieldFlash Minutes 02-18-16.pdf
    File:2015 FieldFlash Minutes 03-03-16.pdf
    File:2015 FieldFlash Minutes 03-10-16.pdf
    File:2015 FieldFlash Minutes 03-22-16.pdf
    File:2015 FieldFlash Minutes 03-29-16.pdf
    File:2015 FieldFlash Minutes 04-05-16.pdf
    File:2015 FieldFlash Minutes 04-12-16.pdf
    File:2015 FieldFlash Minutes 04-19-16.pdf
    File:2015 FieldFlash Minutes 04-26-16.pdf