Field Flashing Synchronous Generator

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
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
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

 * 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

System Process

 * 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

System Circuit
Detailed Operating Procedure:

1. Prime mover spins rotor to initiate a black start

2. User presses momentary button 1 to toggle SSR on connecting batteries to field windings of generator.

3. Battery bank provides excitation voltage and current directly to generator sufficient power is provided from synchronous   generator to run the field exciter.

4. User presses latching button 2 to toggle Excitation ON bit on UNITROL 1020 to start its excitation current output.

5. Generator reaches DCH Supervision Alarm setpoint on UNITROL 1020 and UNITROL 1020 toggles DCH Supervision Alarm I/O to  switch SSR back off, disconnecting batteries from field circuit.

6. Generator reaches rated output power.

7. ABB field exciter controls excitation in steady state operation

Planned Tests for Exciter System
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.

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