Week 2

Last week, we had done some preparation work for our project, such as consulting some introductions, articles and reports which are related to power system fault analysis as well as the method of simulation by MATLAB. In this week, we set about designing the model of power system applying the simulink tool of MATLAB software. Owing to the provided demos of power system simulation, we can make more sense to what we are going to do. An example is shown below in the Figure 1,

Figure 1

but it is relatively more actual power system design with complicated components and connections compared to the requirement of our project. However, it is a useful case indeed provided for us to make a simplification. According to the complex demo, we took an attempt to design several circuits with some electrical components like three phase source, distributed parameters line, impedance, transformers and that sort of thing. One of our designs is demonstrated in the Figure 2.

Figure 2

For consideration of different faults, a three phase fault device  should be added into the circuits. Seen from the window at the bottom right corner, it is the property and setting of three phase fault component. 

• Ticking all of the fault refers to the balanced three phase fault.  
• Only ticking one of the A, B, C fault and 'Ground Fault' refers to the unbalanced single line to ground(SLG) fault. 
• Only ticking two of the A, B, C faults means the unbalanced double line(LL) fault.
• Ticking two of the A, B, C faults and 'Ground Fault' means the unbalanced double line to ground(DLG) fault.

During the process of building the circuit, one problem was appeared that how to set the value of several parameters for each components. In addition, we didn't have any idea about how to give a reasonable value for a power system.

Our supervisor gave us an simple example with particular values which can be regarded as references. Also the distributed parameters line is difficult to calculate the exact values, so our supervisor advise us using the 'three-phase series RLC branch' which is easy to figure out. Moreover, the transformer is always essential in a real power system. Besides, the synchronous generator and the asynchronous motor are suggested to be instead of simple source and load.

Based on the proposal from supervisor, the general designs after improvement are revealed in the following Figure 3,4,5. 

Figure 3

Figure 4

Figure 5

Since the property setting error, the result of simulation isn't like the desired waveform and we managed to achieve the goal bu debugging each parameter, but the consequent can make us satisfied.