Adjustable Governor for Synchronous Generator - SEL

Problem Statement
A power system is used to develop power at a specific voltage and frequency. Load changes on the output of a power-generating system will cause fluctuations in both voltage and frequency. The fluctuations are undesirable and must be prevented or at least mitigated.

Specifications
Hard fast specifications for this project have not been communicated, which is normal for senior design. Instead, we have been given boundary performance metrics and are asked to develop minimum specifications based upon industry standards. This section of the transcript attempts to capture the various statements that have been made with respect to performance and present them for review to establish agreement with our customers and to sanity check the team’s current understanding. Corrections and feedback is solicited.

The first performance metric to discuss is Settling Time (ST). ST will be defined (at least for this paper) as the time between a deviation of output frequency from the system setpoint and the moment when the system returns to the setpoint with no significant over or undershoot. SEL has stated that they want the system response to be fast. Also, the current VFD governor control is not fast enough. Thus, the current system performance will be used to establish an absolute minimum performance for our project. Dr. Johnson has further clarified that many power system governors have ST values around 5 seconds, and this is considered good performance in the industry. During the meeting, the team brought up that we would like to compete (in a good way)

against each other. The external feedback group will try to improve ST over the model characterization group, and vise versa.

The second performance metric to discuss is precision. Dr. Johnson suggested we consider how tightly we will control frequency. For instance, will the output frequency be controlled to 60 with an error of 1 hz, or an error of .1 hz, or .01 hz. The key here is to what precision with the output frequency be held to its set point. The team will look to requirements placed on Avista or Idaho Power to establish a starting point for this specification.

MODBUs & EFB


The code to construct and send simple MODBUS data packets has been written and is currently undergoing tests on the hardware and VFD. With the code, a user has the ability to specify three different field-attributes that make up a MODBUS frame; node address, function code, and an array of data bytes to be sent. The code will automatically calculate the frame’s 16-bit CRC and append it to the end of a frame transmission. In its current form, the MODBUS implementation results in the VFD displaying an increasing number of UART errors each time a packet is sent. As a demonstration, I have attempted to form and send packets in attempt to cycle the VFD through it’s start-up procedures, accelerate to a reference, and then coast to a stop. The search for why UART errors exist is an ongoing effort and all layers of implementation are being scrutinized (from physical to data-link). An interface logic-analyzer (by IFTools) loaned to me from an SEL-coworker is being used to investigate.

RTDS Simulations
RTDS, REAL TIME DIGITAL SIMULATOR simulates the control-loop governs the existing system such that it responds as if it were a different, larger industrial power system like hydroelectric, steam, or gas.



SEL 411L
We are using SEL-411L Relay Protection and Automation System for detecting the change in frequency in the system while applying load. SEL 411L allows us to capture any change happing over period of time for further analysis.

Document Archive

 * Team Meeting Minutes


 * [[File:091115 Byte Back minutes.pdf]]
 * [[File:091815 Byte Back minutes.pdf]]
 * [[File:092515 Byte Back minutes.pdf]]
 * [[File:100215 Byte Back minutes.pdf]]
 * [[File:100915 Byte Back minutes.pdf]]
 * [[File:101615 Byte Back minutes.pdf]]
 * [[File:102315 Byte Back minutes.pdf]]
 * [[File:2015_Byte_Back_minutes_103015.pdf]]
 * [[File:2015_Byte_Back_minutes_110615.pdf]]
 * [[File:2015_Byte_Back_minutes_111915.pdf]]
 * [[File:2015_Byte_Back_minutes_120315.pdf]]