Expert In Power System Simulation_MATPOWER_MATLAB

To solve adn guide solutions using MatPower

Task2003:
A DSO must electrify an area where there are two primary substations (PS1 and PS2). On the basis of
the arrangement of the MV loads (Ls) and secondary substations (SSs), the DSO is planning to carry
out two MV grid sections (each of which is powered by its own PS), according to the diagram shown in
the figure; you are asked to:
a) determine the commercial section of the bare conductors of the overhead lines (OHLs) and those of
underground power cable lines (PCLs);
b) provide, in the switching substation (SWS), the installation of a capacitor bank (C) for the power
factor correction of the PS1 at a value not lower than 0.95;
c) propose and verify the solution in such a way that, following-up a fault occurred, e.g., in a line or in
the PS, the faulty section can be, partially or entirely, re-powered (with a backwards feed) through the
healthy grid supplied from the other PS.
Any missing data must be chosen explaining the reason for the choice. In order to simplify the control
of voltage values and the possible violation of their limits, it is suggested to use a power flow analysis
based on MATPOWER.
Task 2003
The MV distribution network, represented by the single-line diagram drawn in the figure, consists
of several feeders one of which is a very long overhead power line (OHL). This line is protected by
a circuit breaker (CB) which is controlled by several relays, two of which are relays 51 and 67 (see
Table I).
With switch SW open, you are asked to determine trip thresholds of the relay 51 and/or the relay 67
when:
1. a three-phase fault occurs at the sending terminal end of the OHL;
2. a line-to-line fault occurs at the receiving terminal end of the OHL;
3. a single-phase to ground fault (through a resistance RF = 0 Ω) occurs at the receiving
terminal end of the OHL.
After the determination of the Petersen’s coil reactance, XP, tuned 90% to the zero sequence
capacitance of the MV network, and the determination of resistance value of the resistor, RP, in
parallel to the Petersen coil, in such a way to have a resistive fault current equal to 20 A, with
switch SW closed, you are asked to determine trip thresholds of the relay 51 and/or the relay 67
when:
4. a three-phase fault occurs at the receiving terminal end of the OHL;
5. a line-to-line fault occurs at the sending terminal end of the OHL;
6. a single-phase to ground fault (through a resistance RF = 5 Ω) occurs at the receiving
terminal end of the OHL.
For single-phase to ground faults (questions 3 and 6) also evaluate the voltages at the fault point and
at the bus-bar.