1Algorithm of Load Flow Simulation and Fault Analysis using MiPower Software Akshay Sharma Scholar M.E., Department of Electrical and Electronics Engineering, NITTTR, Bhopal, India
[email protected] Laxmikant Nagar Scholar M.E., Department of Electrical and Electronics Engineering, NITTTR, Bhopal, India
[email protected] Abstract - This paper focuses on load flow analysis in an electrical power system. A load flow analysis program using MiPower software has been developed using a fast decoupled load flow algorithm based on a Y bus admittance matrix to determine operating parameters of system bus. A network of 6 bus system is considered as a test case. The Simulink model developed using MiPower software results in fast iterative process. GUI (Graphical user interface) will be provided with the program as the component of the tool box. Fault analysis is carried out on one of the transmission line of 6 bus systems for frequently occurring single line to ground fault to observe the operating parameters of the system under consideration in terms of AC voltage, AC current and AC power waveform at the grid before and after the occurrence of Single line to ground fault. Key Words: Load flow analysis, MiPower, Single line to ground fault, Fault analysis, operating parameters transmission line of 6 bus systems for frequently occurring single line to ground fault. The simulation results and reports are analyzed in section 5. 1.1SYSTEM DESCRIPTION Figure1 shows a single line diagram of a 6-bus system with two identical generating units, five transmission lines and two transformers. Per-unit transmission line series impedances and shunt susceptances are given on 100 MVA base, generator's transient impedance and transformer leakage reactances are given in the accompanying table1.1 I. INTRODUCTION Load flow studies are used to ensure that electrical power transfer from generators to consumers through the grid system is stable, reliable and economic. It deals with the flow of electrical power from one or more sources to loads consuming energy through available paths. Unlike the traditional circuit analysis, a load flow study usually uses simplified notation such as a one-line diagram and per-unit system. Considerable research has already been carried out in the development of computer programs for load flow analysis of large power systems. However, these general purpose programs may encounter convergence difficulties. There are many solution techniques for load flow analysis. The solution procedures and formulations can be precise or approximate. In this paper we have attempted Fast decoupled load flow analysis to build a power system using the random data taking care of all the parameters required for the simulation and analysis. We have modeled an 11kv generation, 110kV transmission 6 bus grid using MiPower software. We begin with description of 6 bus system under section 1.1 and data collection and methodology required for modeling is discussed in section 3 and in section 4, Load flow study is carried out using Fast decoupled load flow analysis and voltage profile of buses are analyzed. In addition to load flow analysis, Our attention is on unbalanced (asymmetrical) fault analysis is carried out on one of the Figure 1 “6 Bus” System model Table-1.1 Bus Code p–q 3–4 3–5 3–6 5–6 4–6 Impedance Zpq 0.00 + j0.15 0.00 + j0.10 0.00 + j0.20 0.00 + j0.15 0.00 + j0.10 Line Charging Y'pq/2 0 0 0 0 0 Generator Data: G1 = G2 =100 MVA, 11 kV with X'd =10 % Transformer Data: T1 = T2 = 11/110 kV, 100 MVA, leakage reactance = 5 % All impedances are on 100 MVA base Bus width. Specify the Base MVA and Base frequency. III. Following table 3. if necessary change the Base-voltages. Zone number and Contingency weightage data if it is other than the default values. and finally presents complete Simulink model for selected type of 6 bus system [1]. then bus name can be given as NE and the bus description field can be North East [1]-[2]. standard libraries will be loaded along with the database. As generators G1 and G2 have same parameters. MODELLING OF COMPONENTS The Simulink Models of various components of power system network are essential for the assessment of desired performance requirements. and for system stability studies related to planning and operation of power system. we begin with description of various components. Elements 3-5 & 4-6 have common parameters. To draw the line select the positions in between two buses and connect one bus to another bus by double clicking the mouse button. then a short name is given in the bus name field and the bus description field can be used to abbreviate the bus name. Therefore 3 libraries are required for transmission line. color. The same applies for transformers also. If the data is furnished. modify the breaker ratings for required voltage levels in Breaker Ratings tab otherwise accept the default values and create the database to return to Network Editor. Modify the Area number.1 gives the data for other buses. In this section. For this example these standard libraries are not needed.2 II. Bus Name Nominal voltage 1 Bus 1 11 kV 4 Bus 4 110 kV 5 Bus 5 110 kV 6 Bus 6 110 kV 3. and relay libraries are required only for relay co-ordination studies. generator). 2.1 MiPower-DATABASE CONFIGURATION Power System Network Editor is used to select menu option Database Configure. If bus name is more than 8 characters. If Libraries are selected. Transmission line data for Line 3-4 in Line & Cable Library is shown in figure 6.2 BUS VOLTAGE CONFIGURATION In the network editor. For example let us say the bus name is northeast. The details of that line as shown in figure 5. Uncheck the Power System Libraries and Standard Relay Libraries. Figure 4 Line Element ID 3. Bus description field can be effectively used if the bus name is more than 8 characters. Since the impedances are given on 100 MVA base. Configure Database dialog is popped up. Browse the desired directory and specify the name of the database to be associated with the single line diagram. for the design and coordination of supplementary control and protective circuits. . elements 3-4 & 5-6 have common parameters. 2. Procedure to enter the data for performing studies using MiPower is discussed below. Draw a bus and a dialog appears prompting to give the Bus ID and Bus Name. only one generator library is required. DATA INTERPRETATION In transmission line data.1 BUS SIMULINK MODEL MiPower tool bar provide Bus icon. because all the data is given on pu for power system libraries (like transformer. Table 3. Figure3 Bus Data Dialogue Follow the same procedure for remaining buses. configure the base voltages for the single line diagram in menu option and again configure base voltage.2 TRANSMISSION MODEL LINE SIMULINK Figure 2: Configuration Information Transmission Line icon provided on power system tool bar. Database manager with corresponding Bus Data form will Element ID number and the details of that line with corresponding Line\Cable Data is to be provided on database manager.1 Bus Data 2 3 Bus Bus 2 3 11 110 kV kV Bus No. appear. Usually the minimum and maximum voltage ratings are ± 5% of the rated voltage. check the pu status in Electrical Information tab. line\cable. Enter Generator data in the form as shown in figure 11 below.1 0.4 GENERATOR SIMULINK MODEL Generator icon is provided on power system tool bar. . Element ID dialog is shown in figure 10.3 TRANSFORMER SIMULINK MODEL Two Winding Transformer icon is provided on power system tool bar.3. 3. Draw the generator by clicking on the Bus1.Two Winding Transformer Data in the form is shown in figure 8. Figure 7 Transformer Element ID Figure 10 Generator Element ID Transformer Element Data form is shown in figure 7.2 Transmission Line Element/ Library Data Line Number 1 2 4 5 6 Line Name Lne Line Line Line Line 3-4 3-5 3-6 4-6 5-6 De-Rated 100 100 100 100 100 MVA Positive 0 0 0 0 0 Sequence Resistance Positive 0. To draw the transformer.15 0.2 0.3 entered in Transformer library form is shown in figure 9. Table 3. The data form table 3. click in between two buses and to connect to the From bus.3 Figure 5 Line\Cable Data Figure 6 Line\ Cable Library Figure 8 Two Winding Transformer Data In the similar way enter other transformer details from table 3.1 0. double click on the From Bus and joint it to another bus by double clicking the mouse button on the To Bus [5].2 follow the same procedure for rest of the elements. Data for remaining elements given in the following table 3.15 Sequence Reactance Thermal 100 100 100 100 100 rating Figure 9 Two Winding Transformer Library Table 3.3 2nd Transformer Detail Transformer Number 2 Transformer Name 2T2 From Bus Number 6 To Bus Number 2 De Rated MVA 100 3. Connect another generator to Bus 2. Figure 12 Generator Library Table 3. Figure 15 Load Flow Studies 4. Part of the Report generated by MiPower is shown in Figure 16 IV. SIMULINK MODEL OF 6 BUS SYSTEM The Simulink model now incorporated into MiPower to analyze and design of power systems. total minimum & maximum MVAR limit of Generator are 0 & 120 respectively.4 Figure 14 Load Flow Analysis Study Info option provides following dialog.1 RESULT OF LOAD FLOW ANALYSIS Load flow analysis is done by Fast Decoupled Load flow Method. Select Fast Decoupled Load Flow and enable Optimal Load Flow Analysis [4].4 IV. The simulated model of 6 bus system is shown in figure 13. Figure 16 Report of Load Flow Analysis Figure 13 Simulink Model . Figure 11 Generator Data The details of Generator 1 are provided on Generator Library as shown in figure 12.Load flow studies. Following dialog will appear.4 Generator 2 details Bus Number 2 De-Rated MVA 100 Specified Voltage 11 Scheduled Power 80 Reactive Power 0 Minimum Reactive power 60 Maximum Note: To neglect the transformer resistance. in the multiplication factor table give the X to R Ratio as 9999. In similar way enter its details as given in the following table 3. LOAD FLOW ANALYSIS Load flow analysis can be performed using menu option as Solve . The report of the simulation shows the specified MW generation as 160 MW. Manohar.prdcinfotech. FAULT ANALYSIS (SINGLE LINE TO GROUND) To solve short circuit studies choose menu option Solve Short Circuit Analysis or click on SCS button on the toolbar on the right side of the screen. Vol. [2] [3] [4] [5] [6] Figure 19 Graphical View . VI. and Simultaneous faults. A MiPower load flow simulation program has been developed using a Fast decoupled load flow algorithm to calculate and control the voltage. vol. Khalid Mohamed Nor.5 V. Line to line. Nov. and the real and reactive power flowing in each line. 15. “Power System Stability & Control. No. “Semi Newton Load Flow Algorithms in Transient Security Simulations. McGraw-Hill.1. REFERNCES [1] K.com. 2004. Vivek Raveendran. “Reusability Techniques in Load Flow Analysis Computer Program. The procedure is directly applicable to other unbalanced operating conditions of interest to the power system analyst for various short circuits such as three phase to ground fault. 4. 5. 5.3 RESULT OF FAULT ANALYSIS The result of Short Circuit Analysis is developed by creating a line to Ground Fault at Bus 5 using MiPower is shown in Figure 19.” The International Journal of Engineering and Science Vol. Short circuit study will be executed. Electric Power Research Institute. No. S.2 GRAPHICAL ANALYSIS For the Graphical analysis of Short circuit studies. Sumit Tomar. Select Import Button of MiGraph Screen following Graphical representation will appear to understand the behavior of electric power systems under the occurrence of a short circuit as shown in Figure 19. Jovanovic. Double line to ground. The principal information obtained from the load flow study is the magnitude and phase angle of the voltage at each bus. P. pp. Click on Report to view the report file. Jan 1994. “Mppt and Simulation Figure 18 Short Circuit Analysis for a Grid-Connected Photovoltaic System and Fault Analysis. 19. 2012. 2013 [cited 08 Jan 2013].1 CASE STUDY INFORMATION Figure 19 Report on Short circuit analysis Figure 17 Short Circuit Studies Afterwards click Execute. 3. Available from: www. Single phase open fault. Short circuit analysis screen appears [5]-[6].html Prabha Kundur. May 2000. Prdcinfotech. 2. India: Bangalore Center.” IEEE Transaction on Power Systems.” 2nd ed.” International Journal of Scientific & Engineering Research.” IEEE Transaction on Power Systems. vol. CONCLUSION Load-flow studies are important for planning future expansion of power systems as well as in determining the best operation of existing systems. select Graph option of Short Circuit Analysis as shown by dialog Box in Figure 18. Analysis and Optimisation of a Power System Network.Case Study. “Modeling. Taufiq Abdul Gani. Sobha Rani. 158-166. June 2012.com/products. determine real and reactive power flows. Simulation. 5.