Field Flashing Synchronous Generator



Black Start System for a Synchronous Generator
Sponsor:	Schweitzer Engineering Laboratories
Team Name:	The Flash
Duration:	Fall 2015 - Spring 2016
Faculty Advisor:	Dr. Feng Li
Technical Advisor:	Dr. Johnson
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 | edit source]

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 | edit source]

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 | edit source]

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 | edit source]

Black Start Diagram

System Process[edit | edit source]

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

Specs Table[edit | edit source]

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 | edit source]

System Circuit[edit | edit source]

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 | edit source]

Front of Prototype Board	Front Connections
	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
	Element details: Resistor: 1.0 Ohm Relay: Electromechanical Relay Switch: Standard mechanical switch

Final System Design[edit | edit source]

Front of Black-Start board
No Excitation to System
Attempt to Start Generator With AVR

RTDS[edit | edit source]

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
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
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
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
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)

Project Learning[edit | edit source]

ABB AVR[edit | edit source]

ABB Unitrol AVR

Planned Tests for Exciter System[edit | edit source]

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 | edit source]

Team "Flash"
Picture	Biography	Discipline
Will Parker	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	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	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 | edit source]

Meeting Minutes[edit | edit source]