Corrective Actions for Relieving Overloads in a Transmission System

Project Plan

Team

Dec05-03

Client

MidAmerican Energy Company

Matt Mitchell

Faculty Advisor

Dr. McCalley

Team Members

Tien Huynh, EE

Zakaria Joundi, EE

Bryan Pauls, EE

Mark Scheibe, EE

REPORT DISCLAIMER NOTICE

DISCLAIMER: This document was developed as a part of the requirements of an electrical and computer engineering course at IowaStateUniversity, Ames, Iowa. This document does not constitute a professional engineering design or a professional land surveying document. Although the information is intended to be accurate, the associated students, faculty, and IowaStateUniversity make no claims, promises, or guarantees about the accuracy, completeness, quality, or adequacy of the information. The user of this document shall ensure that any such use does not violate any laws with regard to professional licensing and certification requirements. This use includes any work resulting from this student-prepared document that is required to be under the responsible charge of a licensed engineer or surveyor. This document is copyrighted by the students who produced this document and the associated faculty advisors. No part may be reproduced without the written permission of the senior design course coordinator.

Date Submitted

March 1, 2005

1

Table of Contents

List of Figures...... iii

List of Tables...... iv

List of Definitions...... v

1Introductory Material

1.1Abstract

1.2Acknowledgement

1.3Problem Statement and Solution

1.3.1Problem Statement

1.3.2Problem Solution

1.4Operating Environment

1.5Intended User and Intended Use

1.5.1Intended User(s)

1.5.2Intended Use(s)

1.6Assumptions and Limitations

1.6.1List of Assumptions

1.6.2List of Limitations

1.7Expected End-Product and Other Deliverables

1.7.1Microsoft Excel Workbook

1.7.2MatLab Program

1.7.3Documentation

2Proposed Approach

2.1Functional Requirements

2.2Constraints Considerations

2.3Technology Considerations

2.4Technical Approach Considerations

2.5Testing Requirements Considerations

2.6Security Considerations

2.7Safety Considerations

2.8Intellectual Property Considerations

2.9Commercialization Considerations

2.10Possible Risks and Risk Management

2.11Project Proposed Milestones and Evaluations Criteria

2.12Project Tracking Procedures

2.12.1Meetings

2.12.2E-Mails

3Statement of Work

3.1Task 1 - Problem Definition

3.1.1Subtask 1a - Problem Definition Completion

3.1.2Subtask 1b - End User and End Uses Identification

3.1.3Subtask 1c - Constraint Identification

3.2Task 2 - Technology and implementation considerations and selection

3.2.1Subtask 2a - Identification of Possible Technologies

3.2.2Subtask 2b - Identification of Selection Criteria

3.2.3Subtask 2c - Technology Research

3.2.4Subtask 2d - Technology Selection

3.3Task 3 - End-Product Design

3.3.1Subtask 3a - Identification of Design Requirements

3.3.2Subtask 3b - Design Process

3.3.3Subtask 3c - Documentation of Design

3.4Task 4 - End-Product Prototype Implementation

3.4.1Subtask 4a - Identification of Prototype Limitations

3.4.2Subtask 4b - Implementation of Prototype End-Product

3.5Task 5 - End-Product Testing

3.5.1Subtask 5a - Test Planning

3.5.2Subtask 5b - Test Development

3.5.3Subtask 5c - Test Execution

3.5.4Subtask 5d - Test Evaluation

3.5.5Subtask 5e - Documentation of Testing

3.6Task 6 - End-Product Documentation

3.6.1Subtask 6a - Development of End-User Documentation

3.6.2Subtask 6b - Development of Maintenance and Support Documentation

3.7Task 7 - End of Product Demonstration

3.7.1Subtask 7a: Planning the Demonstration

3.7.2Subtask 7b: Demonstrating to the Faculty Advisor

3.7.3Subtask 7c: Demonstrating to the Client

3.7.4Subtask 7d: Demonstrating to the Industrial Review Panel

3.8Task - 8 Project Reporting

3.8.1Subtask 8a: Development of Project Plan

3.8.2Subtask 8b: Development of the Project Poster

3.8.3Subtask 8c: Development of the Design Report

3.8.4Subtask 8d: Development of the Project Final Report

4Estimated Resources and Schedule

4.1Personnel Effort Requirements

4.2Other Resource Requirements

4.3Financial Requirements

4.3.1Costs

4.3.2Estimated Project Cost

4.4Project Schedule

4.5Deliverable Schedule

5Closure Materials

5.1Project Team Information

5.1.1Client Information

5.1.2Faculty Advisor Information

5.1.3Student Team Information

5.2Closing Summary

5.3References

Appendix A: Small-Scale Model Explaination...... 25

List of Figures

0.1.Figure listing the levels of severity of a TLR...... v

1.1.Block diagram of the proposed program...... 1

4.1. Project Schedule...... 22

4.2 Deliverable Schedule...... 23

List of Tables

4.1 Personnel Effort Resource Requirement...... 21

4.2 Estimated Project Costs...... 22

List of Definitions

Economic dispatch: the allocation of the total load demand among generating units in order to achieve the most economical production of power.

Generation shift factors: gives the fraction of change in injection at a certain bus and that appears on a branch in a given network.

Incremental cost: the increase in cost in dollars per increase in mega-watt hours.

Incremental heat rate curve: curve used to determine the values to which the units should be loaded to decrease the fuel costs to a minimum.

Monotonic unit (MU): a generator that produces more power output as fuel input is increased.

MW: mega-watt unit used to measure real power.

Non-monotonic unit (NMU): a generator that can have an increase in power output with no increase in fuel input

PTDF’s: power transfer distribution factor is a generation of the shift factor.

TLR: transmission load relief.

TLR levels: the levels correspond to different types of actions that may be taken. These levels are summarized in the figure below. [1]

Unit Commitment Data: whether a unit is committed to being turned on and running during a specific time period.

VBA: Visual Basic Application.

1

1Introductory Material

This section will introduce the project, including the abstract, acknowledgements,problem statement and solution, operating environment, intended users and uses,limitations and assumptions, expected end-product and other deliverables.

1.1Abstract

Due to a change in demand, high voltage transmission circuits can become overloaded. Overloads are resolved by the dispatch of power based on hand calculations performed by a reliability coordinator. The solutions focus completely on reliability and disregard the economics of their decisions. The project team will develop a software application that receives data from a power network and produces a recommended change for the network to control overloads in an economically minded manner. Major milestones will be the development of an algorithm to calculate optimal economic dispatch for a given monotonic network, the integration of an existing algorithm for manual input of a non-monotonic network, the implementation of the algorithm in Microsoft Excel, and the presentation of the completed software to the client. Optimal results will allow for power to be dispatched at the lowest cost to the client while protecting the reliability of the network.

Figure 1.1. Block diagram of the proposed program

1.2Acknowledgement

The design team would like to thank our faculty advisor Dr. Jim McCalley and our client, Matt Mitchell, from MidAmerican Energy. Their donated time, technical advice, and support are greatly appreciated.

1.3Problem Statement and Solution

The problem statement is broken up into two separate sections; one that defines the general problem area and another that describes the proposed approach to the solution.

1.3.1Problem Statement

When MidAmerican Energy has scheduled or unscheduled network outages they must have the ability to quickly fix overloaded high voltage transmission circuits. The central reliability coordinator is in charge of correcting the problem(s) that have arisen. To solve these problems, the coordinator adjusts generator output on specific generators, which typically will solve the overloaded lines. When adjusting generation, the economics are usually not taken into account. The team’s goal is to devise a program that will make the economic part of the redispatch of the generators easier for the reliability coordinator.

1.3.2Problem Solution

The solution to the problem would take into account the following items in order to provide the best solution: generation shift factors, incremental heat rate curve, unit commitment data, total system production cost, and level of MW redispatch needed to relieve the overloaded lines. Generation shift factors will be given in an approximated form to the team from MidAmerican Energy. Incremental heat rate curve data will be taken from a current senior design project and from MidAmerican Energy. Unit commitment data and total system production cost will be also be given by MidAmerican. The general power flow problem will be solved by using the MatLab linear program solver and answers will be exported and displayed within a worksheet inside of Microsoft Excel. A small-scale system with the solution steps have been included in Appendix A.

1.4Operating Environment

The end-product will be installed and used in a comfortable and safe environment inside the control center at MidAmerican Energy Company. The computer that the software is executed on should be kept away from high moisture areas. The operable temperature can range from 45 to 90 degrees Fahrenheit. The preferred temperature for the environment should be at room temperature, which is 72 degrees Fahrenheit. A high moisture area can be hazardous to the computer and can cause it to have hardware problems which will lead to the prevention of using this software. The hazard that the product may be exposed to are computer viruses that can spread through this software and cause it to be corrupted. The computer is not to be dropped or thrown.

1.5Intended User and Intended Use

This section is divided into two parts, one to cover the intended user(s), and the second is to cover the intended use(s).

1.5.1Intended User(s)

The software will be designed for the reliability coordinator(s) at MidAmerican Energy who is responsible for reducing the loading on the circuit when an overloading condition occurs. The adequate educational background of the intended user is determined by MidAmerican before hiring for that position. The user(s) must also have experience using Microsoft Excel; specifically how to run a VBA program inside of Excel. Basic knowledge of generator shift factors is a plus.

1.5.2Intended Use(s)

The software written with MatLab will be used to determine the most cost effective way to redispatch the generation unit(s) in order to relieve overloaded high voltage transmission circuits. Redispatch usually involves shifting power production from one or a group of generation units to one or a group of other generators to resolve the overload in an optimized manner using linear programming.

1.6Assumptions and Limitations

This section contains the assumptions and limitations of the project.

1.6.1List of Assumptions

  • Project ideas remain in the project team
  • The end-product will be used in the United States
  • A working system takes priority over an efficient system
  • MidAmerican will supply previous network data to help design and test the algorithm
  • Network data shall include the eastern interconnection of 20,000 buses
  • Incremental heat rate curves shall be piece-wise linear
  • Losses are negligible

1.6.2List of Limitations

  • Software must acquire system data, compute the algorithm, and display the final dispatch solution within five minutes of detected overloads
  • Only MidAmerican generators (50) shall be considered when shifting generation

1.7Expected End-Product and Other Deliverables

The end-product will include three items, a Microsoft Excel Workbook, MatLab program, and documentation to explain how to use and maintain the product.

1.7.1Microsoft Excel Workbook

The final product will use Microsoft Excel as the interface, where data will be entered and all of the calculations will be made inside of MatLab. A small program written in VBA will call the self-executing MatLab file to solve the problem using the linear program solver. The solutions will then be imported back into Microsoft Excel to ensure that all of the material the reliability coordinator needs to make a decision is inside of one program. Comments will be incorporated into the VBA code in case it needs to be modified in the future.

Monotonic generator outputs will have to be calculated by the program, but there needs to be an option to manually enter non-monotonic generators as well. The program should be able to give the solutions within five minutes of the information being entered into Excel.

1.7.2MatLab Program

Once the data is imported into MatLab, calculations will be made to set up the general power flow problem. Once all of the matrices are set-up, the problem will be put into the linear program solver, which should provide the most economical dispatch of power from each generator. The solutions will then be exported into Microsoft Excel. To ensure that this part of the problem is able to transfer to computers that do not have MatLab installed, the code will be made into a self-executing program. All of the functionality of the program will still be able to be utilized and there just will be no need for MatLab to be installed on the computer that will run this section of code.

1.7.3Documentation

Along with the Microsoft Excel workbook and the self-executing MatLab program, documentation about the program will be included. This will give details on how the MatLab and VBA code were created, the full-length code with comments included, test results of the simulation, and a PowerPoint presentation showing a step-by-step demonstration of how to properly enter in data and run the simulation. The algorithm upon which the program was based on will also be given to the client. An evaluation of the results that were obtained from the algorithm is also going to be included.

2Proposed Approach

The proposed approach contains the functional requirements of the project, the constraint considerations, technology considerations, safety considerations, intellectual property considerations, commercialization considerations, possible risks and risk management, project milestones and evaluation criteria, and the project tracking procedures.

2.1Functional Requirements

The requirements needed for complete functionality of the end-product are as follows:

  • Must allow manual input of PTDF’s in matrix form
  • Must read in system data, compute the generation shifts, and display the final dispatch solution within a five minute execution time.
  • Must identify the least cost redispatch from among specified generators to reduce loading of overloaded circuits to within ratings.
  • Algorithm must solve for a 20,000 bus/50 generator system

2.2Constraints Considerations

The constraints that determine the design of the end-product are as follows:

  • Microsoft Excel is a preferred medium
  • Use of linearized network modeling will result in some error in flow reductions obtained from identified generation shifts. Typical expected error should be assessed.

2.3Technology Considerations

The considerations based upon the project team’s knowledge of a technology and its ability to perform the needed tasks is as follows:

  • Programming Language: The programming languages to be used are VBA and MatLab. First, VBA is an unfamiliar language for the project team, but was chosen because it is the programming language that can be used inside of Excel, which the client wants to be used as the interface. MatLab coding is more familiar to the team, which was learned in previous courses.
  • Mathematics Platform: The mathematics platforms to be use are Microsoft Excel and MatLab. Microsoft Excel was chosen because it is the platform used by the client. MatLab was chosen because it can handle the large matrices needed to define the 20,000 bus system

2.4Technical Approach Considerations

The technical approach considerations define the process that will be followed to complete the project.

  • An algorithm should be created which uses network data provided by MidAmerican Energy Company
  • VBA should call the self-executing MatLab code
  • MatLab should be used to perform matrix computations

2.5Testing Requirements Considerations

Testing considerations determine the types of testing to be used, and determines the types of acceptance criteria to be used.

  • Testing should begin by using a small-scale model, which should be in complete working order before moving onto the full-scale model.
  • Testing should be performed using previous network data supplied by MidAmerican Energy
  • Functionality of the software application and algorithmwill be confirmed by comparing the software results to results calculated by hand using a small-scale model.
  • Accuracy will be assessed in two ways:
  • Optimality: by comparing cost of the identified solution with the cost of other possible solutions
  • Feasibility: by modeling identified solutions using an AC power flow to determine the level of error due to DC network assumptions
  • After testing by the group, MidAmerican Energy will test the software and give feedback to the team.

2.6Security Considerations

The project’s security considerations are divided in two segments. Security considerations during the project and security considerations related to the operation of the end-product.

  • During Project: Project knowledge and the generation test data supplied from MidAmerican Company shall be kept within the group.
  • Operation of the End-Product: While developing the software multiple copies and periodic backups will be made in order to ensure no loss of data.

2.7Safety Considerations

There are no safety considerations.

2.8Intellectual Property Considerations

The data will be provided by MidAmerican Energy Company to the team. The following are the intellectual property values that are required of the team:

  • The team will come up with the algorithm for developing the software.
  • Permission is required from MidAmerican Energy Company to use their logo.
  • The team will keep the data provided by and the algorithm designed for MidAmerican Energy confidential, unless otherwise specified.

2.9Commercialization Considerations

The commercialization of the end-product shall be decided by MidAmerican Energy once the team hands it over to them. The team shall not decide or plan for the commercialization of the end-product.

2.10Possible Risks and Risk Management

The team may encounter the following risks:

  • The end-product may not work properly because of bad algorithm.
  • Due to health issues or any other circumstances, the team may encounter losing a group member(s).
  • The team maylose time to work on the project due to problems encountered, which are beyond their control.
  • Team members may have miscommunication with each other and the project wouldn’t progress as scheduled.
  • The project may not meet the deadlines.

Solution to the risks that the team may encounter:

  • The team must be organized and comment all of the code so that the team can come back to fix it if necessary. Must also make the code as flexible for changes as possible to fix a possible bad algorithm.
  • All members must be aware of how the code works so that each member can work on it if member(s) cannot continue working with the team, or misses a meeting.
  • The team can meet additional times and try to make up the lost time.
  • The team must make sure every member is involved and that they complete their tasks so the project may progress.
  • The team must make sure to meet deadlines. If the team gets behind schedule, additional meetings should be held to catch up. There should be an emphasis on staying ahead of schedule.

2.11Project Proposed Milestones and Evaluations Criteria