The main objective of this project is to analyse the different parameters of five bus bar power system. Analysis of these bus bars parameters must be supported by both theoretically and simulated results obtained by using Power World Simulator (PWS). Power World Simulator (PWS) used for engineering analysis, power system visualisation, simulation and analysis tool . In this project five bus bars attached to each other according to their specific input data. According to power system terminology, bus is the node at which two or more different devices joined known as buses. In electrical power distribution, bus bar thick strip that conduct electricity to other electrical apparatus .
In this project, input data for five bus power system provided and the required power system designed on the Power World Simulator as per requirement. When five bus power systems designed on PWS instructions completely followed in order to make required design. After that one-line diagram is obtained shown in figure 1. Then design critically analysed by performing simulation in order to check voltages and flows on other network components.
Figure 1: One-line diagram for five bus power system
2. Problem Analysis
When designing five bus bar power system different problem were faced because designing is quite complex and skilled operation.
2.1 Data analysis
Before start designing in order to draw one-line diagram input data for buses were properly analysed and also transmission line data and transformer data. As four variables associated with each bus: voltage magnitude Vk, phase angle δk , real power Pk, and reactive power Qk. By these variables analyse which were input data and which were unknown from the provided input data.
2.2 Designing analysis
In designing, general designing principles were followed in order to design five bus power system. The five-bus power system modelled in Power World Simulator (PWS), this software used for power system analysis. Although some guide provided to start modelling the five-bus power system in PWS. Modelling was quite complex and take several times because of different adjustment and given parameters was properly entered for buses, transmission lines, and transformers in order to simulate model properly. After completing the required model on PWS, power flow can be visualized and also other parameters that were unknown when simulation performed.
2.3 Software analysis
According to the main objective of the project mainly focused on the modelling as per requirement and five-bus power system modelled on the Power World simulator for the purpose of simulation. This software requires some technical skills. That's why general principles must follow in order to simulate the desired model otherwise problem might occur.
3. Problem Solutions
3.1 Data solution
The one-line diagram can obtain by inserting the bus data, transmission line data and transformer as per requirement for the five-bus power system. The bus input data enable to distinguish between different kinds of buses. These buses are as follows:
Slack bus ( V and δ - input data)
Load bus (P and Q - input data)
Voltage controlled bus (P and V - input data)
Similarly transmission line input data provide series resistance, reactance, and shunt charging, transformer input data provide series resistance and reactance. With the help of these input data one-line diagram can be achieved by using the software.
3.2 Designing solution
The required model designed on Power World Simulator which permits the system to perfectly model as single phase system. The connection between devices drawn by a single line in order to join them, therefore one-line diagram achieved. The desired model has five buses and by available input data for all devices model can be achieved by inserting all devices parameters properly. Make sure that all the devices connected to each other, otherwise it's impossible to achieve the required results. In PWS, generator have circle shape with a rotor at the centre, large arrows represent the load and transmission line represented by simple line. By following the general principles required one-line diagram can be achieved.
3.3 Software solution
Five-bus power system modelled on PWS as per requirement and then simulation performed to determine the unknown variables. By this software different techniques like Gauss-Seidel and Newton-Raphson techniques can be performed. By PWS, Y bus (Bus Admittance Matrix) can be easily obtained and compare with theoretical values of admittance matrix. PWS has some different and interesting specification if compare with MATLAB and Proteus. Simulation can easily perform by PWS but make sure that all the given parameters properly inserted.
The main objective of this project to analyse the five-bus power system that means to critically analyse the parameters for buses, transformers, and transmission lines. These parameters can be determined theoretically by performing different theoretical techniques but the result obtained have some human error and time consuming, that's why in order to remove these error Power World Simulator used. By following the modelling analysis and solution, implementation of five-bus power system can be achieved by using the software Power World Simulator (PWS). PWS used in order to compare both simulated and theoretical results.
Power World Simulator has two modes, Edit mode and Run mode. Edit mode used to add buses, load and many other components as shown in figure 4.1
As this project based on Power World Simulator as per requirement and by following the bus input data totally five buses inserted in order to full fill the requirement. In the Edit mode, five buses inserted to desired location. All buses parameters set as provided and adjusted in Bus Field Options dialog and there are three load buses, one slack bus, and one voltage control bus. Between bus1 and bus5 transformer line connected and similarly between bus4 and bus3. This can be done graphically by selecting insert, transformer. Buses 2, 4 and 5 connected by line, all these line have different parameters, line series resistances, series reactance and MVA limit inserted in the line information dialog. The required model has two generators one on slack bus1 and other on voltage control bus3, and also two loads, one load inserted on bus2 and other load inserted on voltage control bus3. Parameters for buses, transmission lines and transformers properly set as given. By following all these principle required one-line diagram obtained as shown in figure 4.2
Power World Simulator also has other mode, Run Mode which is used for the simulation. When simulation performed all the unknown values appeared on the screen. The arrows show the direction of power flow as shown in figure 4.3. On this final model different technique and changes performed as per requirement.
5. Results and Discussions
After completing the one-line diagram on Power World Simulator simulation performed. Through simulation all the unknown values determined and these parameters shown in table 5.1
After that Y-matrix can be easily displayed in PWS by selecting case information, solution details, Y-bus. The Y-bus derived by other system parameters which cannot be change directly. These simulated values compare with the theoretical values. Y-bus matrix shown in table 5.2
Theoretical values for Y-bus admittance matrix elements are given below:
Off diagonal elements:
Y42 = Y24 = - 089276 + j 9.91964
Y52 = Y25 = - 1.42284 + j 15.8714
Y51 = Y15 = 3.72 - j 49.72
Y54 = Y45 = 2.8568 - j 31.7428
Y43 = Y34 = 7.458 - j 99.44
Y11 = 3.72 - j 49.7
Y22 = 2.3211 - j 25.791
Y33 = 7.458 - j 99.44
Y44 = 11.21 - j 121.25
Y55 = 8.0053 - j 97.324
The theoretical values compare with the simulated values as obtained in table 5.2 almost same result obtained.
After computing the Y-matrix, Gauss-Seidel and Newton-Raphson techniques apply in Power World Simulator in order to solve the power flow problem and compare the solution obtained by PWS. PWS gives the calculation by default Gauss-Seidel technique, so the bus record table 5.1 shown above is the solution for Gauss-Seidel. The solution computed by Newton-Raphson technique shown in table 5.3.
After computing the solutions from both the techniques and compared with each other. It observed from both the results that there was not much difference in both results except in generated reactive power (MVAr). Newton-Raphson gives more accurate results because it performs more iteration as compare to Gauss-Seidel.
In the case when demand increases at bus 2 set as almost double, as a result load on the transformer between bus 3 and bus 4 increases and also reactive power in generator at bus 3 increases which indicates that losses in the generator also increases. It is observed that the acceptable generated range at bus 2 is 844MW, demand increases but power at bus to not upto required demand.
In PWS the shunt capacitor connected on bus 2 in parallel with load and this method of connecting capacitor in parallel with load is known as power factor correction and decreases the apparent power of source, so source current also decreases. As the line connected between the load and generator line losses decrease and less line voltage drop across the line. The capacitor of 210 Mvar rating inserted at bus 2 and decreases the losses from 46.50 MW to 29.1MW as shown in area field option dialogue below:
The connected capacitor shown in figure 5.2 which supplying the reactive power of 188.1Mvar. Capacitive reactance rating depends on assumed voltage 1.0 pu and this loss due to capacitor reactance varies directly with the square of the voltage. The voltage at bus 2 increases to 0.95 pu as per requirement also shown in figure 5.2
After that another possible changing in five-bus power system performed to find the low voltage problem, for that another transmission line inserted in parallel between bus 4 and 2 having the same parameters with the already exciting model and then simulation performed. After that all the parameters analyse and at bus 3 MVar of the generator decreases and hence losses. Load on line between bus 3 and 4 also decreases. At bus 2 the voltage increases to 0.96 pu and losses at bus 2 decreases shown area field dialogue given below.
By inserting transmission line power factor also improve and simulated one-line diagram shown in the figure 5.3. The choice for inserting the line is less preferable as compare to capacitor in real implementation because of the cost factor but both these can be used for power factor improvement.
In PWS, the real and reactive mismatches equation by simply selecting the option mismatches option, the table given below shows real and reactive power mismatches. The convergence tolerance is ±1% of their rated value.
The transmission line between bus 2 and 4 is removed for maintenance. After that five bus power system again simulated and its operating condition is not acceptable because transmission line between bus 5 and bus 4 is overloaded. Then in order to run the system under normal condition the load at bus 2 and bus 3 are equally shared in such a way that the overloading on the transmission line between bus 5 and bus 4 is reduced.
After completing this project, we get enough information about how to draw bus power system by using Power World Simulator (PWS). This simulation software easy to use and give brief description of each step, voltage, load angle etc. Most importantly this software is less time consuming and free from any human error. This project gives very good understanding and knowledge about bus power system and clear idea about the different parameters that mainly analysed during simulation.
Now a day's mostly all industries using such kind of software's in order to check any fault and transmission losses. Mainly electric consumption have increased and also the number of interconnections, so future planning become more complex. The software like PWS efficiently calculates power-flow solution of any numbers of bus power systems. This project gives an idea to analyse different kind of transmission design.