- Parent Category: Coordination
- Category: 9-Bus Systems
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# 9-Bus System (System I)

** I. Introduction:**

\(\bullet\) In this test case, 9-bus interconnected distribution system with one single-end fed and equal impedances for all the lines is considered.

\(\bullet\) This system has \(3\phi\) fault at the midpoint of each line, as shown in the below figure, with no backup protection for relays \(\{R_{17},R_{19},R_{21},R_{23}\}\).

\(\bullet\) Bus 1 is supplied by a power source of \(100 \text{ MVA}\), \(33 \text{ kV}\) with a source impedance of \((0+j0.1) \ \text{p.u}\). Also, the lines impedances are equal to \((0+j0.2) \ \text{p.u}\).

\(\bullet\) All the directional overcurrent relays (DOCRs) have same CT ratio (\(CTR\)) of \(500:1\), and all these DOCRs are considered to be numerical, in which both plug-setting (\(PS\)) and time-multiplier setting (\(TMS\)) are continuous.

\(\bullet\) The lower and upper limits of \(PS\) of each DOCR are calculated based on the following practical equaltions:

$$PS^{min}_{i} = \frac{OLF \times I_{n,i}}{CTR} \text{..... (1)}$$

$$PS^{max}_{i} = \frac{2}{3 CTR} I^{min}_{f,i} \text{..... (2)}$$

where \(I_{n,i}\) is the nominal current rating of the circuit protected by the relay \(R_i\). \(OLF\) is the overload factor (with \(OLF=1.25\)), and \(I^{min}_{f,i}\) is the minimum fault current that should be detected by the \(i\)th relay.

\(\bullet\) In addition, relays \(\{R_{17},R_{19},R_{21},R_{23}\}\) are assumed with no backup.

\(\bullet\) Also, the minimum operating time of each relay \(T^{min}\) is taken as 0.2 s.

\(\bullet\) The rest data are given below *(click on them for bigger size)*:

** II. Single-Line Diagram:**

\(\bullet\) This single-line diagram was drawn by Ali R. Alroomi in Sept. 2013 and all the necessary data were coded in MATLAB m-files.

** III. Files:**

\(\bullet\) System DATA (MATLAB, m-file Format) [Download]

\(\bullet\) Results Tester (MATLAB, m-file Format) [Download]

** IV. References (Some selected papers that use this system):**

[1] P. Bedekar and S. Bhide, "Optimum Coordination of Directional Overcurrent Relays Using the Hybrid GA-NLP Approach," *IEEE Transactions on Power Delivery*, vol. 26, no. 1, pp. 109–119, Jan. 2011.

[2] F. Adelnia, Z. Moravej, and M. Farzinfar, "A New Formulation for Coordination of Directional Overcurrent Relays in Interconnected Networks," *International Transactions on Electrical Energy Systems*, vol. 25, no. 1, pp. 120–137, Nov. 2013.

[3] M. N. Alam, B. Das, and V. Pant, "A Comparative Study of Metaheuristic Optimization Approaches for Directional Overcurrent Relays Coordination," *Electric Power Systems Research*, vol. 128, pp. 39–52, Nov. 2015.

[4] F. A. Albasri, A. R. Alroomi, and J. H. Talaq, "Optimal Coordination of Directional Overcurrent Relays Using Biogeography-Based Optimization Algorithms," *IEEE Transactions on Power Delivery*, vol. 30, no. 4, pp. 903–911, 2015.