Reference no: EM132381867
ELECENG3110 Electric Power Systems and ELECENG7074 Power Systems PG Assignment - Power System Steady-State Performance, The University of Adelaide, Australia
Investigation of power system steady-state performance -
The objective of this assignment is to investigate the steady-state performance of the six bus power system depicted in Figure 1 (attached). You will employ the educational version of the Power World power-flow program to conduct the required power-flow studies.
The deliverable outcome is to be a comprehensive technical engineering report detailing clearly and concisely the conduct of your investigation that clearly summarizes and discusses the key findings from your analysis and the technical conclusions that you draw from the studies. The report should address each of the matters and questions listed in the following scope of work. Credit will be given for innovative studies and analysis that either reveal other aspects of system performance or which improve the performance of the system.
With reference to the above guidelines your report is expected to convey information to other engineers about key aspects of the performance of the system and it is intended for selective reading. The latter point means that you should organize your report into sections with informative headings.
1. Scope of work
(a) System model and parameters. Clearly tabulate key parameters of the network and its components including, but not limited to,
- nominal voltage levels of the network buses;
- equipment current and/or MVA ratings;
- transformer impedances in per-unit of both system MVA base and the transformer MVA base;
- transmission line lengths, surge-impedance loads (SIL), line parameters in per-unit on the system MVA base and in per-unit of the SIL.
You will need to use the PowerWorld software and its documentation to navigate to the various forms and tables that itemize the relevant parameters. Treat this exercise as the normal process of becoming familiar with a new software package.
(b) Analysis of base case. For the base case scenario provided solve the power-flow and tabulate the solution including:
- the bus voltage magnitudes and angles;
- the load connected to the main load centre at bus 2;
- the output (i.e. P & Q) from the generators;
- the real and reactive power flow and losses in each transformer and transmission line;
- comparison of the transmission line power flows with their SIL.
Document the real and reactive power losses of the entire system.
Explain why the performance of the base case scenario is unsatisfactory.
(c) Effect of changing load [intact system]. It is important to understand how the system bus voltages, power and reactive power flows change as the system load changes. Plotting curves of key system variables as the system load changes is very useful for this purpose. Adjust the load at bus 2 to zero and solve the load flow. Record the following variables:
(i) Bus 2: voltage, real and reactive power
(ii) Bus 1: voltage, generator real and reactive power output
(iii) Bus 3: voltage, generator real and reactive power output
(iv) Bus 4 to 6: voltage
(v) Lines & transformers: real and reactive power into each bus
Increase the load at bus two to 50 MW with a power factor of 0.95 (lag) and record the same set of variables. Repeat, progressively increasing the load in increments of 50 MW (with power factor of 0.95 (lag)) to 1000 MW.
Plot curves of the recorded variables against the system load. Take care to reduce the number of plots by combining voltage curves on a single plot, generator real and reactive power outputs on a single plot, etc. Ensure that your plots include meaningful legends, that axes are labelled with variable names and units and that they are given meaningful captions.
Carefully analyse the curves and report your key observations and discuss the engineering significance of the results.
(d) Effect of changing load [contingencies]. The performance of the system following the outage of a transmission element is very important when assessing the secure operating limits of the system. In this part plot the bus 2 voltage as a function of load power (in 50 MW increments, with a power factor of 0.95 (lag)) for each of the following individual contingencies:
(i) Transmission line from bus 5 to 2 disconnected.
(ii) Transmission line from bus 4 to 2 disconnected.
(iii) Transmission line from bus 5 to 6 disconnected.
Overlay the PV curves for each of the three contingencies together with the corresponding PV curve of the intact system on a single plot.
Carefully analyse the curves and report your key observations and discuss the engineering significance of the results.
(e) Voltage control with load-bus SVC. A potential solution for the inadequate performance of the base case is to install a Static Var Compensator (SVC) at the major load bus. A SVC can be represented for analytical purposes by a generator with zero power output and with reactive power limits set appropriately. Thus, to determine the required SVC capacity connect a synchronous generator to the load bus with P = 0 and set the minimum and maximum reactive power limits to a very large value (e.g. 9.999 x 103 MVAr).
Determine the SVC capacity that would be required to achieve a load bus voltage of 1.0 pu. Comprehensively document your power-flow solution and compare the network voltages and power flows with those obtained in the base case. How have the system real and reactive power losses changed as the result of introducing the SVC? Interpret and clearly explain your findings in terms of power system concepts.
(f) Optimization of voltage control. Based on your understanding of the factors that affect the real and reactive power losses in a network systematically adjust generator and SVC voltage set-points and/or transformer tap positions in order to minimize the real and reactive power losses in the system. Ensure that bus voltages remain within acceptable limits and that all equipment operates within their limits current / MVA limits. Usually, during normal operation it is desirable for network bus voltages to be within the range from 0.95 pu to 1.0 pu. It is usually desirable for generator bus voltages to be set close to 1.0 pu, say within the range 0.98 pu to 1.02 pu.
Document the adjustments that you make, explain the reasons why you make them and report the effect of the adjustments on reactive power flows and system losses. In conducting your search for a good set of voltage control settings it is productive to adhere to the principle of small adjustments and avoid making adjustments to multiple settings simultaneously.
Document the best voltage control settings that you are able to determine for this operating condition and clearly explain why the settings yield lower losses than the original settings.
How much has the SVC output changed as the result of applying your best set of voltage control settings.
(g) System performance for a range of operating conditions. Based on the case with the SVC that you constructed in (f) conduct studies for the following scenarios and document your findings. In particular document the reactive power generated by the SVC in each scenario.
(i) Transmission line from bus 5 to 2 disconnected.
(ii) Transmission line from bus 4 to 2 disconnected.
(iii) Reduce the output of the bus 3 generator from 520 MW to 200 MW and reduce the load at bus 2 from its expected peak value of 900 MW / 329 MVAr to its minimum value of 200 MW / 66 MVAr.
(Note: Three separate cases are derived from the case that you developed in (f). The first case is derived from the case in (f) by applying the change in (i), the second case is derived from the case in (f) by applying the change in (ii), etc.)
How do the results from these studies help you to decide the capacity of the SVC which will be required to securely operate the system?
2. Factors considered in assessment
This assignment is structured as an engineering investigation and the assignment report will be assessed in that context. Thus assessment will consider:
(a) Completion of the scope of work.
(b) Report organization, brevity and clarity.
(c) Clarity and sophistication in explaining the engineering significance of the findings.
(d) Accurate, relevant and clear application of power system analysis principles to the scope of work.
(e) Accuracy and correctness of results.
(f) Skill in application of the Power World power-flow program.
Students sometimes ask how long should the report be. My answer is that is a question you must decide for yourself based on what you consider to be an appropriate level of analysis and discussion required to clearly and concisely communicate your findings from your investigation to the reader. I doubt that you could achieve this objective in less than 10 pages and I doubt that you would require more than 30 pages.
Attachment:- Electric Power Systems Assignment Files.rar