3.5 Consider the microgrid of Figure 3.68. A three-phase 500 kVA, 440 V Y grounded/3.2 kV delta transformer T, with the per unit reactance of AC bus Local loads 250 kVA DC bus PV generating station DC/AC Inverter m Zyans Local power grid 3.2 kv T2 13.2 KV 440 V/3.2 kV 500 kVA 3.5% 3.2/13.2 kV 500 KVA, 8% Figure 3.68 A one-line diagram of Problem 3.5. PROBLEMS 173 3.5% feeds from an AC source of a PV generating station. The distribu- tion line is 10 miles long and has a series impedance of 0.01 + j0.09 2 per mile. The local load is 250 kVA. The balance of power can be injected into the local utility using a 500 kVA, 3.2 kV Y grounded/13.2 kV delta transformer T2 with the per unit reactance of 8%. Assume the voltage base of 13.8 kV on the local power grid side, kVA base of 500, and the DC bus voltage of 800 V. Compute the following: (i) The inverter and the PV generating station ratings. (ii) The per unit impedance diagram of the microgrid.

3.5 Consider the microgrid of Figure 3.68. A three-phase 500 kVA, 440 V Y grounded/3.2 kV delta transformer T, with the per unit reactance of AC bus Local loads 250 kVA DC bus PV generating station DC/AC Inverter m Zyans Local power grid 3.2 kv T2 13.2 KV 440 V/3.2 kV 500 kVA 3.5% 3.2/13.2 kV 500 KVA, 8% Figure 3.68 A one-line diagram of Problem 3.5. PROBLEMS 173 3.5% feeds from an AC source of a PV generating station. The distribu- tion line is 10 miles long and has a series impedance of 0.01 + j0.09 2 per mile. The local load is 250 kVA. The balance of power can be injected into the local utility using a 500 kVA, 3.2 kV Y grounded/13.2 kV delta transformer T2 with the per unit reactance of 8%. Assume the voltage base of 13.8 kV on the local power grid side, kVA base of 500, and the DC bus voltage of 800 V. Compute the following: (i) The inverter and the PV generating station ratings. (ii) The per unit impedance diagram of the microgrid.

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter3: Power Transformers

Section: Chapter Questions

Problem 3.25P: Consider a single-phase electric system shown in Figure 3.33. Transformers are rated as follows:...

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Similar questions

Consider the single-Line diagram of a power system shown in Figure 3.42 with equipment ratings given: Generator G1: 50MVA,13.2kV,x=0.15p.u. Generator G2: 20MVA,13.8kV,x=0.15p.u. Three-phase -Y transformer T1: 80MVA,13.2/165YkV,X=0.1p.u. Three-phase Y- transformer T2: 40MVA,165Y/13.8kV,X=0.1p.u. Load: 40MVA,0.8PFlagging,operatingat150kV Choose a base of 100 MVA for the system and 132-kV base in the transmission-line circuit. Let the load be modeled as a parallel combination of resistance and inductance. Neglect transformer phase shifts. Draw a per-phase equivalent circuit of the system showing all impedances in per unit.
Consider a single-phase electric system shown in Figure 3.33. Transformers are rated as follows: XY15MVA,13.8/138kV, leakage reactance 10 YZ15MVA,138/69kV, leakage reactance 8 With the base in circuit Y chosen as 15MVA,138kV determine the per-unit impedance of the 500 resistive load in circuit Z, referred to circuits Z, Y, and X. Neglecting magnetizing currents, transformer resistances, and line impedances, draw the impedance diagram in per unit.
In developing per-unit circuits of systems such as the one shown in Figure 3.10. when moving across a transformer, the voltage base is changed in proportion to the transformer voltage ratings. (a) True (b) False
Consider three ideal single-phase transformers (with a voltage gain of ) put together as three-phase bank as shown in Figure 3.35. Assuming positive-sequence voltages for Va,Vb, and Vc find Va,Vb, and VC. in terms of Va,Vb, and Vc, respectively. (a) Would such relationships hold for the line voltages as well? (b) Looking into the current relationships, express IaIb and Ic in terms of IaIb and Ic respectively. (C) Let S and S be the per-phase complex power output and input. respectively. Find S in terms of S.
Consider the oneline diagram shown in Figure 3.40. The three-phase transformer bank is made up of three identical single-phase transformers, each specified by X1=0.24 (on the low-voltage side), negligible resistance and magnetizing current, and turns ratio =N2/N1=10. The transformer bank is delivering 100 MW at 0.8 p.f. lagging to a substation bus whose voltage is 230 kV. (a) Determine the primary current magnitude, primary voltage (line-to-line) magnitude, and the three-phase complex power supplied by the generator. Choose the line-to-neutral voltage at the bus, Va as the reference Account for the phase shift, and assume positive-sequence operation. (b) Find the phase shift between the primary and secondary voltages.
Consider Figure 3.4. For an ideal phase-shifting transformer, the imda nce is unchanged when it is referred from one side to the other. (a) True (b) False
The per-unit equivalent circuit of two transformers Ta and Tb connected in parallel, with the same nominal voltage ratio and the same reactan of 0.1 per unit on the same base, is shown in Figure 3.43. Transformer Tb has a voltage-magnitude step-up toward the load of 1.05 times that of Ta (that is, the tap on the secondary winding of Tb is set to 1.05). The load is represented by 0.8+j0.6 per unit at a voltage V2=1.0/0 per unit. Determine the complex power in per unit transmitted to the load through each transformer, comment on how the transformers share the real and reactive powers.
Reconsider Problem 3.64 with the change that now Tb includes both a transformer of the same turns ratio as Ta and a regulating transformer with a 4 phase shift. On the base of Ta, the impedance of the two comp onents of Tb is jO.1 per unit. Determine the complex power in per unit transmitted to the load through each transformer. Comment on how the transformers share the real and reactive pors.
Consider the three single-phase two-winding transformers shown in Figure 3.37. The high-voltage windings are connected in Y. (a) For the low-voltage side, connect the windings in , place the polarity marks, and label the terminals a, b, and c in accordance with the American standard. (b) Relabel the terminals a, b, and c such that VAN is 90 out of phase with Va for positive sequence.
How to generate 480V three phase 400Hz ac from 230V three phase 60Hz ac source? (Please specify the power components you pick, such as transformers, dc-dc converter, dc-ac converter and/or ac-dc converter, how these components are connected and the key parameters of these components, such as the turns ratio of transformer and the duty cycle functions for the converters.)
(a) The diagram for a single phase 60 MVA transformer is given below. Convert it to a Step-down Autotransformer. Show all the calculations for Vin, Iin, Vout and Iout. Also, show the advantage mathematically.
A bank of three single-phase transformers, each rated 30MVA,38.1/3.81kV, are connected in Y- with a balanced load of three 1, Y-connected resistors. Choosing a base of 90MVA,66kV for the high-voltage side of the three-phase transformer. spify the base for the low-voltage side. Compute the per-unit resistance of the load on the base for the low-voltage side. Also, determine the load resistance in ohms referred to the high-voltage side and the per-unit value on the chosen base.