Chapters 1234

List of Abbreviation FACTS Flexible Alternating Current Transmission System

FDLF Fast Decoupled Load Flow

GNU Gnu's Not Unix (operating system)

IEEE Institute of Electrical and Electronics Engineers

LCPI Line Collapse Proximity Index

MATLAB Matrix Laboratory

PIP Active Power Performance Index

PIV Reactive Power Performance Index

PSAT Power System Analysis Toolbox

PSCAD Power System Computer Aided Design

PV Photovoltaics

SSSC Static Synchronous Series Compensator

STATCON

Static Synchronous Condenser

SVC Static VAR Compensator

TCSC Thyristor Controlled Series Capacitor

UPFC Unified Power Flow Controller

1

AbstractIn the early days, the electrical power grid was a small and localized system that serviced a particular geographic area, with all its’ energy produced near the device or service requiring that energy. After its inception in the industrial age and the realization of the possibility of long distance transmission, the electrical grid has evolved to a wider, more expansive network that incorporated and interconnected different central stations.[1]

This identification of severe lines is able to significantly improve the secure performance of power systems and to reduce the chances of failure of system. Good planning helps to ensure that reliability and security of the system. Contingency ranking analysis helps the power system engineer to give the most priority to notice or monitoring the line flows to which line and monitoring other lines flow in descending order.

2

Table of Contents

Table of Contents

1. Introduction …………………………………………………………………………… 5

1.1 Background ……………………………………………………………………. 6

1.2 Scope of Work ………………………………………………………………… 6

1.3 Design …………………………………………………………………………. 6

1.4 Team Members …………………………………………….…………………... 7

2. Literature Review ………………………………………………….....………………… 8

2.1 Previous Work …………………………………………………………………. 9

3. Design ………………………………………………………………………………… 12

3.1 Requirements ………………………………………………………………….. 13

3.2 Analysis of Requirements and Constrains ……………………………………… 13

3.3 Different Design Approaches/choices ………………………………………… 13

3.4 Developed Design ……………………………………………………………... 13

3.4.1

3

Chapter 1

Introduction

6

1.1Background

The base of the project is the IEEE 14 Bus Test Case which is represent a portion of an electrical power grid. The IEEE 14 Bus Test Case is a transmission system. The data set by IEEE to have various studies like fault analysis, load flow, inter-connected grid and losses reduction problems.

The main idea of the project is to test the system for critical lines and then observe the effects of adding renewable energy sources to the system in improving reliability and reducing the overall losses and in conclusion solving the problems of critical lines.

Usually when a power line is taken down either for maintenance or because of disruptions of natural events, the transmission line outage sometimes increases the total power system losses, cascading outage of transmission lines and finally, causes the system to collapse [1].

Having distributed energy generating sources incorporated in the electrical grid will generate the needed power to compensate for the losses at critical times and prevent the system to collapse. Having these energy generating sources running at all times will reduce the overall losses in the system, which will all be demonstrated later on in the document. The final result is a reliable, reduced losses system.

1.2 Scope of Work

The work that had to be performed for the completion of the project can be summed up in the following key points:

1. Extensive research about the IEEE 14 bus test case.2. Building of the IEEE 14 bus system on PSCAD.3. Running the system.4. Obtaining current and power values and comparing them with the ones

provided with the IEEE 14 bus test case. 5. Actually starting the project by taking down individual lines and obtaining

the branch current values and power flow.6. Locating the lines that carry 150% of the rated current after each line take

down and labeling them as critical.7. Distributing renewable energy generating sources (PV modules in this

project).

7

8. Check and see if the current values in the critical lines were back to regular rated values.

9. Run the system with the added PV modules, without taking any lines down to check if losses really were reduced.

1.3 DesignThe same IEEE 14 bus system was replicated on PSCAD according to the tables provided with the IEEE 14 bus test case archive [2] with PI sections as an equivalent for the transmission lines according to the parameters provided in the IEEE 14 bus system test case tables and description. Several multimeters were distributed all over the system, mainly at the transmission lines to measure the currents and power flow and at the buses to measure the voltages. Photovoltaic (PV) systems were added on specific buses chosen after careful analysis which will be explained in the Design chapter.

1.4 Team MembersThe team consists of four people: Dr. Ayman Faza as the project advisor and students Abdullah Al-Hambouth, Sami Seifan and Serene Abeda. The tasks in the scope of work mentioned earlier in this chapter were divided equally between the three students. The responsibilities of every individual are shown in table below.

Scope # Abdallah Sami Serene1 √ √ √2 √ √ √3 √ √ √4 √5 √6 √7 √ √8 √9 √ √ √

Table 1.1 Team members’ responsibilities.

8

Chapter 2

Literature Review

9

2.1 Previous Work

Several papers were reviewed, all discussing the same subject and aiming to the same objective but each in a different approach applied on the IEEE 14 bus system, in this section the different approaches will be discussed and the results will be stated to be compared with the results of this project.

One of the major goals of this project is to increase the system reliability by testing it for critical lines by analyzing the system and to implement an appropriate solution so that the system can run smoothly without having to experience uncontrolled operation. To test the system for critical lines basically means predicting the effect of transmission line outage on other lines in the system, this technique is called contingency analysis. In this context, contingency means the failure of a power system component like transmission lines. The analysis can be done by calculating performance indices for each contingency separately.

The authors of the paper “Power system security analysis under transmission line outage condition” chose the Line Collapse Proximity Index (LCPI) to identify the most critical transmission lines which is an index based on the effect of power flow in transmission lines, line charging reactance and the direction of reactive power

10

flow with respect to direction of active power flow [1]. After some derivation it is found that

LCPI=4 Acosα ¿¿ (See Appendix B for the full derivation)

LCPI is calculated for each line, ranking them from the line with the highest value (the most critical) to the least. The result of the analysis was that only two lines in the system (line-6 connected between buses 3 and 4 is assigned as rank-1 and line-17 connected between buses 9 and 14 is assigned as rank-2) are critical and cause overloading in other lines. The full result table is provided in Appendix ( )

Another paper “Improved Transmission Line Contigency Analysis in Power System Using Fast Decoupled Load Flow”[3].Explored calculating performance indices for individual contingencies sequentially in the system calculated with the helpFast Decoupled Load Flow (FDLF) in MATLAB. These indicies are active power performance index (PIP) and reactive power performance index (PIV). (The formulas of the indices are provided in Appendix ( )

Based on the values obtained, the lines then are ranked from the most severe (the one with the highest PIv ) to the least. It was found that the outage in line-16 connected between buses 9 and 10 is the most vulnerable one and its outage will result a great impact on the whole system.

While the paper “Contingency Ranking and Analysis using Power System Analysis Toolbox (PSAT)”[4] discussed using the Power System Analysis\ Toolbox (PSAT) which is an open source Matlab and GNU/Octavebased software package for analysis and design of small to medium size electric power systems to find the contingency ranking for the power system, which can be performed by continuation power flow using PSAT for line outage. And found out that line-10 connected between Bus 7 to Bus 9 is most severe line among all 20 lines

Another major goal in this project is minimizing transmission line losses, the book Reactive Power Management of Power Networks with Wind Generation [5] proposed devices that can help reduce transmission line losses, these devices are called FACTS and they are power electronics based devices used to enhance AC system voltage stability and reduce losses. They can be connected in series, in parallel, or in a combination of both [4] as shown in figure 2.1. Series connected FACTS devices used to reduce the effect of long transmission lines inductance value by connecting series capacitor, this will help to decrease the voltage drop between the receiving end bus and sending end bus. On the other hand, Shunt or parallel connected FACTS devices could be consist of shunt capacitive compensation or shunt inductive compensation. Shunt capacitive compensation used to improve the power factor when there is an inductive load connected to the transmission line, while the shunt inductive compensation used to charge the transmission line and increase the power transfer capability.

11

In the paper “Efficient Method of Determining Loss Minimization Using FACTS Devices in Deregulated Power System”[6] the authors chose to place the TCSC between busses 1 and 2 because this line previously had the maximum MW loss, after placing the TCSC in this particular line the MW losses were reduced by 2.68 MW. In another paper “Voltage and Real Power Loss Analysis Incorporating CE-SSSC with VS-SVC Combination through Fruit Fly Optimization” a CE-SSSC with SVC combination was placed between busses 1 and 5 particularly to improve the voltage stability limit and reduce losses, after placing the CE-SSSC with SVC combination the MW losses was reduced by 5.301 MW[7].Meanwhile in “Optimal Location of Thyristor Controlled Series Capacitor for reduction of Transmission Line losses using BAT Search Algorithm” a TCSC model was chosen and located between busses 7-9 depending on the total MW losses, and that caused a reduction in the MW losses by 0.259 MW[8]. The value of real power obtained from different sources mainly vary because of the difference of algorithm used to solve power flow, FACTS device parameters and the methods that used to choose the location of FACTS devices.

In this project the process of identifying the critical lines was different from the ones mentioned earlier. It mainly depended on measuring the line currents after ever contingency and comparing it to the already decided maximum allowable current in the lines, which was 150% of the rated current in the line. This method took a good amount of time but was worth it at the end as the results were used to determine at what buses the solution should be implemented. When the proper solution was implemented to these specific buses not only did the line currents drop below the critical values, an immense reduction in losses was also achieved.

The contribution to previous work will be very clear in the results chapter. Just comparing the results with previous work results will determine the efficiency of the methods in the project.

12

Chapter 3

Design

13

3.1 Requirements

As a simulation project, the only major requirement is the simulation program. The whole design was built using PSCAD. The university provided an educational student lisence of the program for all students to use.

3.2 Analysis of Requirements and Constraints

As mentioned in the abstrast the goal of the project is to provide a more stable reliable power system, so it would be more suitable and realistic if the analysis was performed on a system with a higher number of buses, the available ones in the Power System Test Case Archive [2] were 14, 30, 57, 118, 300 bus systems. This plan was terminated because of two contrains, the time contrain and the fact that the student license of PSCAD had a limit to the number of electrical nodes used in a project (200 electrical nodes to be precise) which was a constrain even for the 14 bus system when the PV systems were implemented.

The vision of the project was not limited to PV systems alone, the original idea was that at least two kinds of renewable energy sources (solar and wind) should be in the new more reliable system, that plan also got terminated because the student license of PSCAD set a limitation for the usage of wind turbine models.

Because the original system before modification had an unexpectedly high percentage of line losses, it was an unnegotiable goal that the percentage of line losses should be reduced by at least 20%, this 20% was considered a kind of a constrain.

3.3 Different Design Approaches/choices

One way to achieve the goal of this project is using power electronic devices (like the ones mentioned earlier in chapter 1) to reduce line losses but a different approach was chosen using renewable energy generating sources, FACTS devices are expensive if implemented in real life, renewable sources are somewhat expensive but are a viable investment.

3.4 Developed Design

3.4.1 IEEE 14-Bus System Info

14

All the info needed about the 14 bus system like figure 3.1 and tables 3.1, 3.2 were taken from the Power Sytems Test Archive online [2], and were the base of our project. The first step we started with is build the system according to the parameters and configurations in tables 3.1, 3.2.

Figure 3.1 IEEE 14 bus system one line diagram

15

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 181 Bus 1 HV 1 1 3 1.06

00.0 0.0 0.0 232.

4-

16.90.0

1.060

0.0 0.0 0.0

0.0 0.0

2 Bus 2 HV 1 1 2 1.045

-4.98 21.7

12.7

40.0 42.4 0.0

1.045

50.0

-40.0

0.0

0.0 0.0

3 Bus 3 HV 1 1 2 1.010

-12.72

94.2

19.0

0.0 23.4 0.0

1.010

40.0

0.0 0.0

0.0 0.0

4 Bus 4 HV 1 1 0 1.019

-10.33

47.8

-3.9

0.0 0.0 0.0

0.0 0.0 0.0 0.0

0.0 0.0

5 Bus 5 HV 1 1 0 1.020

-8.78 7.6 1.6 0.0 0.0 0.0

0.0 0.0 0.0 0.0

0.0 0.0

6 Bus 6 LV 1 1 2 1.070

-14.22

11.2

7.5 0.0 12.2 0.0

1.070

24.0

-6.0 0.0

0.0 0.0

7 Bus 7 ZV 1 1 0 1.062

-13.37

0.0 0.0 0.0 0.0 0.0

0.0 0.0 0.0 0.0

0.0 0.0

8 Bus 8 TV 1 1 2 1.090

-13.36

0.0 0.0 0.0 17.4 0.0

1.090

24.0

-6.0 0.0

0.0 0.0

9 Bus 9 LV 1 1 0 1.056

-14.94

29.5

16.6

0.0 0.0 0.0

0.0 0.0 0.0 0.0

0.19

0.0

10

Bus 10 LV

1 1 0 1.051

-15.10

9.0 5.8 0.0 0.0 0.0

0.0 0.0 0.0 0.0

0.0 0.0

11

Bus 11 LV

1 1 0 1.057

-14.79

3.5 1.8 0.0 0.0 0.0

0.0 0.0 0.0 0.0

0.0 0.0

12

Bus 12 LV

1 1 0 1.055

-15.07

6.1 1.6 0.0 0.0 0.0

0.0 0.0 0.0 0.0

0.0 0.0

13

Bus 13 LV

1 1 0 1.050

-15.16

13.5

5.8 0.0 0.0 0.0

0.0 0.0 0.0 0.0

0.0 0.0

14

Bus 14 LV

1 1 0 1.036

-16.04

14.9

5.0 0.0 0.0 0.0

0.0 0.0 0.0 0.0

0.0 0.0

Table 3.1 Bus data

S3,base=100MVA

Column 01:- Bus number (Integer)Column 02:- Name (Alphabet)

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Column 03:- Load flow area number (Integer) Don't use zero!Column 04:- Loss zone number (Integer)Column 05:- Type (Integer)(P real or active power | Q reactive power | V magnitude of voltage |Theta phase angle ) 0 - Unregulated (load bus, PQ) 1 - Hold MVAR generation within voltage limits, (PQ) 2 - Hold voltage within VAR limits (gen bus, PV) 3 - Hold voltage and angle (swing bus, V-Theta) (must always have one)Column 06:- Final voltage, p.u. (Float)Column 07:- Final angle, degrees (Float)Column 08:- Load MW (Float)Column 09:- Load MVAR (Float)Column 10:- Generation MW (Float)Column 11:- Generation MVAR (Float)Column 12:- Base KV (Float)Column 13:- Desired volts (pu) (Float) (This is desired remote voltage if this bus is controlling another bus.)Column14:- Maximum MVAR or voltage limit (Float)Column 15:- Minimum MVAR or voltage limit (Float)Column 16:- Shunt conductance G (per unit) (Float)Column 17:- Shunt susceptance B (per unit) (Float)Column 18:- Remote controlled bus number

17

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 211 2 1 1 1 0 0.01938 0.05917 0.0528 0 0 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0 0.01 5 1 1 1 0 0.05403 0.22304 0.0492 0 0 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0 0.02 3 1 1 1 0 0.04699 0.19797 0.0438 0 0 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0 0.02 4 1 1 1 0 0.05811 0.17632 0.0340 0 0 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0 0.02 5 1 1 1 0 0.05695 0.17388 0.0346 0 0 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0 0.03 4 1 1 1 0 0.06701 0.17103 0.0128 0 0 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0 0.04 5 1 1 1 0 0.01335 0.04211 0.0 0 0 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0 0.04 7 1 1 1 0 0.0 0.20912 0.0 0 0 0 0 0 0.978 0.0 0.0 0.0 0.0 0.0 0.04 9 1 1 1 0 0.0 0.55618 0.0 0 0 0 0 0 0.969 0.0 0.0 0.0 0.0 0.0 0.05 6 1 1 1 0 0.0 0.25202 0.0 0 0 0 0 0 0.932 0.0 0.0 0.0 0.0 0.0 0.06 11 1 1 1 0 0.09498 0.19890 0.0 0 0 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0 0.06 12 1 1 1 0 0.12291 0.25581 0.0 0 0 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0 0.06 13 1 1 1 0 0.06615 0.13027 0.0 0 0 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0 0.07 8 1 1 1 0 0.0 0.17615 0.0 0 0 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0 0.07 9 1 1 1 0 0.0 0.11001 0.0 0 0 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0 0.09 10 1 1 1 0 0.03181 0.08450 0.0 0 0 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0 0.09 14 1 1 1 0 0.12711 0.27038 0.0 0 0 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0 0.010 11 1 1 1 0 0.08205 0.19207 0.0 0 0 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0 0.012 13 1 1 1 0 0.22092 0.19988 0.0 0 0 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0 0.013 14 1 1 1 0 0.17093 0.34802 0.0 0 0 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Table 3.2 Branch data.

Column 01:-Tap bus number (Integer) for transformers or phase shifters, the side of the model the non-unity tap is onColumn 02:-Z bus number (Integer) for transformers and phase shifters, the side of the model the device impedance is on.Column 03:-Load flow area (Integer)Column 04:-Loss zone (Integer)Column 05:-Circuit (Integer) (Use 1 for single lines)

Column 06:-Type (Integer) 0 - Transmission line

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1 - Fixed tap 2 - Variable tap for voltage control (TCUL, LTC) 3 - Variable tap (turns ratio) for MVAR control 4 - Variable phase angle for MW control (phase shifter)Column 07:-Branch resistance R, per unit (Float) Column 08:-Branch reactance X, per unit (Float) No zero impedance linesColumn 09:-Line charging B, per unit (Float) (total line charging, +B)Column 10:-Line MVA rating No 1 (Integer) Left justify!Column 11:-Line MVA rating No 2 (Integer) Left justify!Column 12:-Line MVA rating No 3 (Integer) Left justify!Column 13:-Control bus numberColumn 14:-Side (Integer) 0 - Controlled bus is one of the terminals 1 - Controlled bus is near the tap side 2 - Controlled bus is near the impedance side (Z bus)Column 15:-Transformer final turns ratio (Float)Column 16:-Transformer (phase shifter) final angle (Float)Column 17:-Minimum tap or phase shift (Float)Column 18:-Maximum tap or phase shift (Float)Column 19:-Step size (Float)Column 20:-Minimum voltage, MVAR or MW limit (Float)Column 21:-Maximum voltage, MVAR or MW limit (Float)

19

3.4.2 IEEE 14-Bus System Components on PSCAD

1. 3-Phase Voltage Source

Figure 3.2 3-Phase Voltage Source

The design has two 3-phase AC voltage sources.

Parameters:

Base MVA (3-phase) =100 MVABase Voltage (L-L, RMS) = 138 kVBase Frequency = 60 HzResistance (series) = 0.001 Ω (ideally zero, but the minimum value allowed by PSCAD is 0.001Ω)Voltage Magnitude (L-L, RMS) = Final Voltage (p.u) * Base Voltage (L-L, RMS)Phase = Final angle (degrees) according to table 3.1

Voltage Magnitude is calculated differently for each generator according to the Final Voltage values which vary from one bus to another. (They are available in the bus data table 3.1)

2. Synchronous Condenser

20

Figure 3.3 Synchronous Condenser PSCAD ready model.The design has three Synchronous condenser models, their presence in this power system is highly important as it supplies reactive power Q for the system when operated overexcited to keep the system balanced. It is worth mentioning that at some point the synchronous condenser could run without a load simply for power factor correction.

The model consists of the following components:

Synchronous Machine

Figure 3.4 Synchronous machine

Parameters

Rated RMS Line-to-Neutral Voltage = 7.91 kV (Set by PSCAD)

21

Rated RMS Line Current = S3∅ ,base

3∗V L−N , base = 4.21424 kV

Base Angular Frequency = 376.99111843 rad/sInertia Constant = 1.988 s

Solid State Exciter with Real Constant

Figure 3.5 Solid State Exciter with Real Constant

The only output of the exciter is Ef which is the computed field voltage and it goes directly to the synchronous machine, this output (Ef) is varied by a control system to maintain the system voltage at Vref.Vref is specified by a Real Constant which is equal to the desired terminal voltage in pu in a base of the synchronous machine. The output voltage of the synchronous machine is measured through Vabc and compared to Vref.

Parameters:

Rectifier Smoother Time Constant = 0.001 s (Set by PSCAD)Controller Lead Time Constant = 0.1s (Set by PSCAD)Controller Lag Time Constant = 0.2s (Set by PSCAD)L-G Voltage Base = 7.91 kV (Same as the synchronous machine which is also set by PSCAD)Line Current Base = = 4.21424 kV (Same as the synchronous condenser)Reverse Resistance = 14285.0 Ω (Set by PSCAD)

Three Phase RMS Meter

Figure 3.6 Three Phase RMS Meter and Output Channel.

22

A 3-phase voltmeter to measure RMS voltage (Vabc of the Solid State Exciter) and an output channel to show the result in a graph.

Parameters:

Meter Type: AnalogRated Voltage (L-L, RMS) = 138 kVSmoothing Time Constant = 0.02 s

Transformer3-phase 2 winding transformer to step up the the terminal voltage of the synchronous condensor to the final bus voltage as shown in table 3.1.

3. Buses

Figure 3.7 Bus.The design is made up of 14 buses with bus 7 not being an actual bus.

Parameters:Base = 138 kV

4. Coupled PI Sections

Figure 3.8 Single line view of PI Section

A π section is used an equivalent for very short transmission lines, but after some modification in its settings and parameters it was (….)

Parameters:

Nominal PI or Coupled PI Model : CoupledLine Rated Frequency = 60 HzRated Voltage L-L = 138 kVMVA for All Phases = 100 MVA

23

+ve Sequence Resistance = Branch Resistance R, p.u+ve Sequence Inductive Reactance = Branch Reactance X, p.u+ve Sequence Capacitive Susceptance = Line Charging B, p.u

5. Transformers

3-Phase 2 Winding Transformer

(a) (b)

Figure 3.9 3-Phase 2 Winding Transformers (a) Y-Y, (b) Y-∆

3-Phase transformers are very important in distrubution and transmission systems; it only makes sense because we need to step up and step down voltages.

In the design two Y-Y connected transformers were used between buses 4-8 and 5-6 for voltage regulation to fix the voltage drop in the lines. While a Y-∆ Transformer was already connected in the ready Synchronous Condenser model.

Parameters:

3-Phase Transformer Base = 100 MVA

Base Operation Frequency = 60 Hz

Winding 1 Line to Line voltage RMS = Final Voltage of bus connected to Winding 1(p.u)* Base Voltage (L-L RMS)

Winding 2 Line to Line voltage RMS = Final Voltage of bus connected to Winding 2(p.u)* Base Voltage (L-L RMS)

3-Phase 3 Winding Transformer

24

From Table 3.2

Figure 3.11 3-Phase 3 Winding Transformer

Parameters:

3-Phase Transformer MVA = 100 MVA

Base Operation Frequency = 60 Hz

Positive Sequence Reactance (#1-#2) = Z12 = Z1 + Z2



Winding 1 Line to Line voltage RMS = Final Voltage of bus connected to Winding(p.u)* Base Voltage (L-L RMS)



6. Fixed Load

Figure 3.10 Fixed Load

Parameters:

25

From table 3.2

Rated Real Power Per Phase = LoadMW3

Rated Reactive Power (+ inductive) Per Phase = Load MVAR3

Rated Load Voltage RMS L-G = Final Voltage of bus(p.u)* Base Voltage (L-N RMS)

7. Capacitive Load

Figure 3.12 Capacitive Load

Parameters:

Three Phase Load (MW) = 3 * (Rated Load Voltage RMS L-G (kV))2 * Shunt susceptance B (1/ohm)

Three Phase RMS Voltage = 138 kV

Rated Frequency = 60 Hz

The previously mentioned components conclude the basic IEEE 14-bus system without the implementation of the PV modules.

Power flow, line currents and bus voltages were measured and documented at this point

26

Figure 3.13 14-bus system on PSCAD

27

3.4.3 Power Flow Analysis

Before adding the PV systems, some sort of analysis had to be done to determine the most suitable buses for the PV addition. Power flow analysis was the best way to go, the process was very simple and repetitive, one line would be taken down and the power flow in other lines is measured and documented (All the results are documented and will be discussed in chapter 4). If a line is taken down and it causes no problems in other lines ( current doesn’t exceed 150% of the rated current in other lines) then it is excluded from the next step.The following figure were of great help in determining PV locations and are worth sharing. Fig 3.14 original pf

28

Figure 3.15 1-5 OFF

Figure 3.16 2-3 OFF

Figure 3.15 shows the result of taking line 1-5 down, it shows the power flow direction with colored arrows. The green arrows indicate normal operation, while the red arrows indicate that the current has exceeded the 150% of the rated current maximum.

Power Flow stayed the same as before the take down.

Current in line 2-5 exceeded the maximum value.

Figure 3.16 shows the result of taking line 2-3 down,


Current in lines 2-4, 2-5, 4-5 and 3-4 exceeded the maximum values.

29

Figure 3.17 2-4 OFF



Current in lines 2-5 and 4-5 exceeded the maximum value.

Figure 3.18 4-5 OFF



Current in lines 2-4, 6-11, 10-11 and 13-14 exceeded the maximum value.



Current in lines 6-11 and 10-11 exceeded the maximum values.

Figure 3.19 9-10 OFF

30


Power Flow changed in line 12-13

Current in line 12-13 exceeded the maximum value.




Current in lines 6-12, 12-13 and 9-14 exceeded the maximum value.




Current in lines 6-11, 10-11 and 9-14 exceeded the maximum value.

After the previous graphical analysis it was decided that the PV systems should be placed on buses 3, 10, 12 and 14.


32

Branches

Current (kA rms)

150% reated current

1 to 2 off

1 to 5 off

2 to 3 off

2 to 4 off

2 to 5 off

3 to 4 off

4 to 5 off

6 to 11 off

6 to 12 off

6 to 13 off

9 to 10 off

9 to 14 off

10 to 11 off

12 to 13 off

1 to 2

0.623856979

0.935785468

0.623936

0.623923

0.62353

7

0.623692

0.623903

0.62368

9

0.623965

0.623739

0.623894

0.623541

0.623258

0.623371

0.623851

1 to 5

0.312965461

0.469448192

0.31292

1

0.400562

0.39124

3

0.391562

0.288126

0.22283

5

0.310816

0.312029

0.308638

0.314465

0.313955

0.311785

0.312112

2 to 3

0.310850505

0.466275758

0.31131

7

0.366131

0.3795

0.347559

0.408241

0.37560

2

0.310915

0.311283

0.311

0.310929

0.309698

0.310766

0.311642

2 to 4

0.244737364

0.367106047

0.24474

8

0.356052

0.396936

0.318183

0.202772

0.37659

3

0.243839

0.244447

0.243231

0.243881

0.242939

0.244037

0.24466

2 to 5

0.185415702

0.278123553

0.18553

2

0.336371

0.294995

0.28505

6

0.155345

0.07661

5

0.182929

0.184739

0.180623

0.187525

0.186682

0.184476

0.185368

4 to 3

0.097764584

0.146646875

0.09786

9

0.048463

0.452693

0.03990

5

0.065219

0.03838

1

0.098938

0.098146

0.099334

0.098047

0.09794

0.098599

0.097825

5 to 4

0.260582991

0.390874487

0.26044

8

0.103966

0.445645

0.42629

7

0.157641

0.208911

0.266749

0.263143

0.273551

0.248562

0.248658

0.261609

0.260761

6 to 11

0.034163157

0.051244736

0.03417

9

0.03456

0.039068

0.03991

0.03452

0.032938

0.05877

8

0.036415

0.049881

0.062726

0.027871

0.017425

0.034684

6 to 12

0.037147855

0.055721782

0.03711

1

0.037039

0.038126

0.03823

1

0.037108

0.036896

0.04137

8

0.039475

0.081317

0.035057

0.043409

0.038204

0.027871

6 to 13

0.0895018

0.1342527 0.08942

6

0.088645

0.093459

0.09383

7

0.089105

0.08842

0.10790

3

0.099052

0.118723

0.080681

0.083144

0.093781

0.097073

9 to 10

0.032438524

0.048657785

0.03244

5

0.036322

0.026359

0.02643

4

0.034812

0.034088

0.01269

6

0.062726

0.029018

0.013813

0.047937

0.046105

0.031616

9 to 14

0.032927842

0.049391762

0.03291

5

0.034952

0.027678

0.02707

5

0.033976

0.034337

0.02221

0.020626

0.03925

0.072563

0.046935

0.027396

0.034648

11 to 10

0.018873387

0.028310081

0.01888

0.021609

0.022856

0.02407

1

0.020721

0.018051

0.04179

0.016726

0.020328

0.032658

0.045689

0.020519

0.019244

12 to 13

0.009510021

0.014265031

0.00951

8

0.009656

0.01042

0.01061

4

0.009636

0.009295

0.01384

9

0.011773

0.026905

0.054072

0.008149

0.009519

0.010628

13 to 14

0.034854708

0.052282061

0.03483

9

0.034436

0.039873

0.04045

2

0.034662

0.033517

0.05996

4

0.046851

0.02825

0.008577

0.025843

0.034875

0.040343

0.033043

3.4.4 PV Generation

After choosing which buses the PV systems should be connected to, the next step is deciding how much active power should the PV give to each bus by putting 3-phase power sources on the decided buses.A 3-phase power source in PSCAD is a component that regulates the bus voltage by injecting complex power to the bus.

The biggest current violation in all cases recorded was the line current of 3-4 when line 2-3 is taken down, so the analysis started with bus 3. A 3-phase generator was added to bus 3 to regulate its voltage by injecting complex power to the bus, but since we only care about active power (because PV only provides active power) a multimeter measures the power provided by the generator. See table ( )

For buses 10 and 14, a generator was added to each bus, taking lines 6-11, 6-12, 6-13, 9-10 and 13-14 down and measuring the amount of active power the generators provide in each case. Then the average of the values for each generator was calculated. These Values are what the PV systems should provide.

For bus 12, by trial and error covering 60% of its load with PV generation was the perfect amount. All of the above is documented in the following table 3.2

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3.4.5 PV Model

Figure 3.13 PSCAD PV Model.

This PV system model was allready built and provided by PSCAD which initially provided 20MW. The needs of the project varried from 20MW as four PV models were implemented on four different buses so some modification had to be done on the scaling to get different wattage. At this point a problem occured which was that the maximum wattage provided by the PV model was only 23 MW. One of the suggested solutions was that another Scale Current Source can be connected in series and it worked perfectly providing us with an unlimited range of output wattage.

How this works basically is that the PV array gets two inputs, solar radiation and cell temperature and its output is dc current that depends on factors like number of modules connected in series per array, number of module strings in parallel per array and number in cell strings in parallel per module. The dc current then goes to a boost converter (DC-DC) and then goes to an inverter because the final output needed should be AC.

Figures 3.14 and 3.15 show the circuit diagrams of the boosy converter and the invetrer.It is worth repeating that this circuit was already assembled and ready to use and only a few changes were made on it by the team memebers.

37

Figure 3.14 Boost converter circuit diagram.

Figure 3.15 Inverter circuit diagram.

38

Chapter 4

Results

39

4.1 Results After PV Addition

4.1.1 Reduction in Line Currents

Branches Current (kA rms)

150% of rated current (kA rms)

Currents with PV 1 to 2 off

1 to 5 off

2 to 3 off

2 to 4 off

2 to 5 off

3 to 4 off

1 to 2 0.623856979 0.935785468 0.620231642 0.62147 0.620133

0.60288 0.620161

0.619906

1 to 5 0.312965461 0.469448192 0.24481451 0.246738

0.271653

0.290083

0.281817

0.252069

2 to 3 0.310850505 0.466275758 0.119430335 0.121721

0.152891

0.014198

0.132922

0.103322

2 to 4 0.244737364 0.367106047 0.142877996 0.14104 0.235148

0.2097 0.182745

0.152099

2 to 5 0.185415702 0.278123553 0.104340677 0.100975

0.222739

0.150472

0.1562 0.108923

4 to 3 0.097764584 0.146646875 0.025860309 0.042441

0.074925

0.098146

0.07049 0.056482

5 to 4 0.260582991 0.390874487 0.182772961 0.17969 0.05525 0.247077

0.2719 0.121439

0.189236

6 to 11 0.034163157 0.051244736 0.027260381 0.027075

0.028303

0.032231

0.03119 0.027272

0.026886

6 to 12 0.037147855 0.055721782 0.021249973 0.0212 0.021536

0.021372

0.031156

0.021556

0.021189

6 to 13 0.0895018 0.1342527 0.059244235 0.058158

0.059765

0.059332

0.087935

0.060077

0.05894

9 to 10 0.032438524 0.048657785 0.020233153 0.018511

0.020605

0.017218

0.01456 0.01769 0.018235

9 to 14 0.032927842 0.049391762 0.011602208 0.011232

0.004127

0.015408

0.01396 0.009641

0.011663

11 to 10 0.018873387 0.028310081 0.014313255 0.014258

0.017546

0.014852

0.01746 0.016167

0.013361

12 to 13 0.009510021 0.014265031 0.009234815 0.00921 0.00942 0.00949 0.01061 0.00943 0.00912

40

4 6 8 413 to 14 0.034854708 0.052282061 0.023512715 0.02551

10.03085

70.02216

10.02664 0.02780

20.03351

7PV GEN @ 3

76 77.9 77 76 77.9 78.2 77.9

PV GEN @ 10 7.2 7.4 7.2 7.2 7.396 7.4 7.4PV GEN @ 12 4.4 4.4 4.4 4.4 4.478 4.5 4.4PV GEN @ 14 20.5 20.8 20.5 20.5 20.8 20.8 20.8

(a)

Table 4.1 Line Currents after PV addition.

4 to 5 off

6 to 11 off

6 to 12 off

6 to 13 off

9 to 10 off

9 to 14 off

10 to 11 off

12 to 13 off

13 to 14 off

0.619723

0.619609

0.620256

0.620302

0.619666

0.619609

0.620316

0.620175

0.619595

0.183972

0.244008

0.243839

0.241717

0.246031

0.244843

0.244249

0.245833

0.242905

0.15183 0.118356

0.112062

0.106575

0.119473

0.118893

0.114113

0.118921

0.108725

0.239412

0.147884

0.1445 0.137143

0.14681 0.148238

0.143246

0.144052

0.142496

0.031654

0.104638

0.10318 0.099589

0.106193

0.105967

0.102163

0.102941

0.103238

0.077103

0.038967

0.04168 0.042814

0.042722

0.04105 0.039218

0.042299

0.042582

0.188444

0.18167 0.184795

0.17846 0.183706

0.179761

0.180015

0.170328

0.046224

0.02923 0.036992

0.043441

0.029542

0.017828

0.034684

0.03338

0.02336 0.02257 0.04891 0.02034 0.02173 0.02171 0.01260 0.01972

41

1 6 5 8 1 2 50.06834

30.06554

60.07505

20.05554

70.06006

70.06050

90.06568

70.05656

70.02431 0.04384

50.01769 0.01299 0.01967

70.03008

50.01759

70.01580

10.03205

90.01930

40.01012 0.02854

30.00743

50.01018

40.01086

60.03534

80.02770

40.01735 0.01497 0.02037

30.02087

70.01305

50.01464

40.02244

50.01178

90.01116

20.01237 0.03600

60.00855

70.00907

90.01003

50.00850

20.02010

70.02692

40.02371 0.02977

20.02665

20.03400

30.04034

30.02498

978 78 77.48 80 77.29 77.5 77.7 78.1 79.27.4 7.35 7.377 7.5 7.252 7.4 7.4 7.4 7.484.5 4.48 4.375 4.5 4.445 4.5 4.4 4.5 4.5

20.8 20.8 20.66 20.9 20.73 20.8 20.8 20.9 20.9

(b) Figure 4.1 Line Currents after PV addition.

42

Table 4.1 shows the line (branch) currents after the addition of PV generation on buses 3, 10, 12 and 14. The values highlighted in green are the ones that were critical before the addition of PV (table 3.3). It is clear how the values reduced below the 150% of the rated current mark. It is even noticable that the current values after PV are even lower than the original rated current values. This brings us to the other section in this chapter which talks about the losses line currents before and after PV.

The line current of branch 6-11 when branch 12-13 was taken down reduced slightly just not enough to pass as noncritical (More than 150% * Rated Current).

4.1.2 Line Losses

Branches Pij (MW) Qij (MW) Pji (MW) Qji Plosses Qlosses1 to 2 156.84 -20.46 -152.4 27.726 4.44 7.2661 to 5 78.842 5.45475 -75.704 1.8116 3.138 7.266352 to 3 76.876 6.1728 -74.07 0.2797

22.806 6.45252

2 to 4 60.688 2.2138 -58.56 0.32238

2.128 2.53618

2 to 5 45.94 2.478 -44.68 -2.633 1.26 -0.1553 to 4 -22.448 5.8034 22.916 -6.0622 0.468 -0.25884 to 5 -62.14 6.2246 62.776 -4.47 0.636 1.75466 to 11 5.887 6.3798 -5.8024 -6.2433 0.0846 0.136556 to 12 8.9442 2.9622 -8.8268 -2.7565 0.1174 0.20576 to 13 20.87 8.9742 -20.506 -8.3722 0.364 0.6029 to 10 7.763 2.0688 -7.7168 -1.996 0.0462 0.07289 to 14 7.826 2.3638 -7.7264 -2.1825 0.0996 0.181311 to 10 -1.9534 -4.2332 1.9845 4.2748 0.0311 0.041612 to 13 2.1562 1.0078 -2.1388 -0.9961 0.0174 0.0116613 to 14 8.0756 3.0998 -7.9376 -3.0704 0.138 0.0294

Ptotal Qtotal15.7743 26.1428

6Figure () line losses before PV

43

Branches Pij Qij Pji Qji Plosses Qlosses1 to 2 156.78 -20.552 -152.36 27.808 4.42 7.2561 to 5 61.834 3.9766 -59.848 -1.536 1.986 2.44062 to 3 25.002 12.924 -24.364 -15.77 0.638 -2.8462 to 4 35.116 4.9108 -34.235 -6.3006 0.881 -1.38982 to 5 24.876 4.268 -24.398 -6.7792 0.478 -2.51123 to 4 5.7972 -8.5488 -5.4852 7.4964 0.312 -1.05244 to 5 -43.098 -1.0424 43.466 1.9426 0.368 0.90026 to 11 4.5088 5.3598 -4.427 -5.2826 0.0818 0.07726 to 12 4.5484 3.7284 -4.4918 -3.6222 0.0566 0.10626 to 13 12.356 11.492 -12.095 -11.086 0.261 0.4069 to 10 1.8072 3.7508 -1.7628 -3.7194 0.0444 0.03149 to 14 -1.9014 1.2132 1.9218 -1.1844 0.0204 0.028811 to 10 -0.5619 -3.2836 0.58744 3.2748 0.02552 -0.008812 to 13 1.8034 1.4272 -1.7764 -1.396 0.027 0.031213 to 14 -2.6288 5.9284 2.6504 -5.8706 0.0216 0.0578

Ptotal Qtotal9.62132 3.5272

Figure () Line losses after PV

By using the method of distributed generation we reduced the losses from ( )P ( )Q MW MVAR

The goal was achieved, better than facts pv is more economical , pay back period of pv

44

Future work

Wind

45

References:

[1] S. Ravindra, V. C. Veera Reddy, S. Sivanagaraju, “Power System Security Analysis under Transmission Line Outage Condition” INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN ELECTRICAL, ELECTRONICS, INSTRUMENTATION AND CONTROL ENGINEERING, vol. 3, issue 1, Jan 2015.

[2] Rich Christie (1993). “Power Systems Test Case Archive” [Online]. Available: https://www.ee.washington.edu/research/pstca/

[3] Amit Kumar Roy, Sanjay Kumar Jain, “Improved Transmission Line Contigency Analysis in Power System Using Fast Decoupled Load Flow” International Journal of Advances in Engineering & Technology, Nov 2013.

[4] Namami Krishna Sharma, Sudhir P. Phulambrikar, Manish Prajapati, Ankita Sharma, “Contingency Ranking and Analysis using Power System Analysis Toolbox (PSAT)”

[5] Hortensia Amaris, Monica Alonso, Carlos Alvarez Ortega, “FACTS”, 2013, in Reactive Power Management of Power Networks with Wind Generation, Springer.

[6] J.amratha Manohar, J.Amarnath “Efficient Method of Determining Loss Minimization Using FACTS Devices in Deregulated Power System” Emerging Trends in Engineering and Applied Sciences, 2011

[7] L.Jebaraj, C. Christober Asir Rajan, Irisppane Soubachie, “Voltage and Real Power Loss Analysis Incorporating CE-SSSC with VS-SVC Combination through Fruit Fly Optimization” Wesas Transaction on Power Sytems, vol. 10, 2015

[8]B. Venkateswara Rao, G.V. Nagesh Kumar, “Optimal Location of Thyristor Controlled Series Capacitor for reduction of Transmission Line losses using BAT Search Algorithm” Wesas Transaction on Power Sytems, vol. 9, 2014

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https://www.ee.washington.edu/research/pstca/

Chapters 1234

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