Optimal Placement of Capacitors in a Distribution System

Abstract 

Optimal capacitor placement is concerned with the optimal location of capacitors in a distribution system such that energy losses are reduced to a minimal value and the voltage profile and power factor of the system is improved. The reactive power can be controlled in order to improve the voltage profile and minimize the system loss. Generally, some load bus voltage might violate their upper or lower limits during system operation due to disturbances and/or system configuration changes. The technical losses can be minimized by generally considering the optimal placement of capacitors in both the transmission and distribution systems. This helps in minimizing the cost of investment and therefore, maximizing the returns.

This project involves optimization problem and various optimization methods have been reviewed for optimal capacitor placement. The test power system was modeled in Digsilent PF software. Load flow simulation was done to determine the system losses before and after compensation. Digsilent also provided an optimal capacitor placement tool which utilizes Tabu search algorithm. The Tabu search algorithm in Digsilent provided an easier way for optimal capacitor placement since the code already exist in Digsilent programming language. A methodology utilizing Tabu search method in Digsilent was proposed therefore. The results obtained from the algorithm were satisfactory and the total cost of investment was minimized, through minimizing the power loss, the size of capacitors and improving the voltage profile. 

Contents

Declaration ......................................................................................................................................2

Acknowledgement ..........................................................................................................................2

Dedication .......................................................................................................................................3

Abstract ...........................................................................................................................................4

Chapter 0ne .....................................................................................................................................8

1.0 Introduction ...............................................................................................................................8

1.1 Background ...........................................................................................................................8

1.2 Problem statement .................................................................................................................9

1.3 Justification .........................................................................................................................10

1.4 OBJECTIVES .....................................................................................................................11

1.4.1 Main objective ..............................................................................................................11

1.4.2 Specific objectives ........................................................................................................11

Chapter two ...................................................................................................................................11

2.0 Literature review .....................................................................................................................11

2.1 Background .........................................................................................................................11

2.1.1 SOURCES OF REACTIVE POWER ..........................................................................12

2.1.2 Advantages of reactive power ...................................................................................... 14 

2.1.3 Need for reactive power ...............................................................................................14

2.1.4 Advantages of good voltage profiles ............................................................................14

2.1.5 Operational mode of capacitor banks ...........................................................................15

2.1.6 CAPACITOR VOLTAGE LIMITS .............................................................................15

2.1.7 Methods of voltage control ...........................................................................................16

2.2 OPTIMISATION METHODS ................................................................................................ 21

2.2.1 SIMULATED ANNEALING .......................................................................................... 21

2.2.2 EXHAUSTIVE SEARCH METHOD .......................................................................... 22

2.2.5 LINEAR DETERMINISTIC OPTIMISATION METHOD ........................................ 23

2.2.6 Tabu search ................................................................................................................... 24

CHAPTER THREE ...................................................................................................................... 25

3.0 METHODOLOGY ................................................................................................................. 25

3.1 Problem formulation ........................................................................................................... 26

3.2 Optimization procedure ....................................................................................................... 27

3.3 Constraints ........................................................................................................................... 28

3.4 Summary of optimization process ....................................................................................... 31

CHAPTER FOUR ......................................................................................................................... 32

4.0 Results and discussion ............................................................................................................ 32

4.1 Voltage profile results ......................................................................................................... 32

4.2 Tabu search results .............................................................................................................. 34

5 Conclusion ................................................................................................................................. 35

6 Recommendations ...................................................................................................................... 37

7.0 References ............................................................................................................................... 38

Appendix .......................................................................................................................................