UNC-Charlotte's Power Systems Teaching · PDF fileUNC-Charlotte's Power Systems Teaching lab...

UNC-Charlotte's Power Systems Teaching lab

UNC-Charlotte: College of Engineering


B. Chowdhury

Panel Session Title: Existing and Proposed Power Systems Laboratories for the Undergraduate Curriculum

PES GM 2014

1



Outline• Background - Energy

Production & Infrastructure Center (EPIC) and its role in education

• Innovative features of Lab• Traditional experiments• New experiments• Example experiment:

Investigating 3-phase OH line • Example experiment: Solar PV

panel characterization

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EPIC and its Role

• EPIC and its role in energy education– Founded by the energy industry for workforce

development and applied research in energy– Cluster hirings (6 new faculty members hired within last

three years in power and energy)– Energy concentration – College revamping curriculum to

add an energy concentration across most disciplines.– The lab is the result of the new focus on interactive classes

and lab work– EPIC scholarships/assistantships

3



Innovative Features

• Equipment can be configured to create exercises for– Electric machines and drives– Power systems– Smart grid concepts, microgrid management, distributed

generation, renewable energy integration, energy storage, etc.• From basic electromagnetic (fluxes and field) properties to

renewable energy-centric microgrid operation.• Individual racks may be interconnected to form full power

system models with generation, distribution and loads.• Equipment may be wheeled into the classroom for

demonstrations.



Traditional Experiments in The Power System Laboratory

Experiment DescriptionPower measurements in R-L-C loads

Wattmeters are used to measure power in three-phase wye- or delta-connected loads.

Three-phase transformers

Three-phase transformer connections, e.g., delta-wye, wye-wye, etc. are studied. In addition, open- and short-circuit tests reveal transformer model parameters.

Generator synchronization

Synchronous generators are synchronized to the grid using different synchronizing techniques; phase sequence is examined.

P and Q control with synchronous machines

Excitation control is used to control active and reactive powers at the terminals of a synchronous machine. Over- and under-excited operations are examined.



New Experiments in The Power System Lab - Partial List

Experiment Description

Transmission line performance, fault studies, line protection

ABCD parameters; line performance calculations;short circuits; reactive power compensation;series/parallel connection of lines of unequal lengths.

Grid-tied and off-grid PVtechnologies

Testing the optimum tilt in response to the sun’s angle; I-V characteristics; off-grid PV system in direct power mode and storage mode; anti-islanding.

Grid-tied and off-grid windtechnologies

WT control concepts; operating at varying wind speeds; optimum operating points under changing wind conditions; response to high and low voltage “fault-ride-through”; operating off-grid wind with energy storage.

Smart grid controlExploring hybrid systems using wind and PV power in a microgrid; voltage control using SCADA; protection issues in the distribution network with DG.



Transmission line benchFeatures:• Line length (model): 150km/300km• R, L, C representation.• May be varied.• May be loaded with R, L, C loads• Adjustable 3-phase power supply• Metering



Transmission line model and performance

• Operate the line under no-load, surge impedance loading, and short-circuit conditions for the two line lengths to derive line performance data:– Voltage increase on open-circuit lines– Voltage drop as a function of line length– Voltage drop as a function of power factor– Capacitive and inductive power losses on a line– Phase shift on a line

• Design reactive (L and C) compensation with varying loads.• Verify system performance under symmetric and

unbalanced faults (SLG, LLG, LL) • Set protective relays (OC, distance, differential, etc.)



Example experiment: Investigating 3-phase overhead line

• Investigate behavior of an overhead line under– no load, matched load and short circuit conditions– determine line efficiency.– Students will connect the lines to C, L and mixed

loads, and attempt to compensate reactive power in the lines.

• Determine SIL for the two line lengths– Adjust RLoad at the receiving end to match set

value of P.



Lab station showing hardware for PV experimentation

Features:Complete system• 10-W polycrystalline solar

module• 500-W halogen lamp with

dimmer;• Three 120 VA independent solar

emulators.

• Solar charge controller• Lead-acid batteries.

• Off-grid inverter and grid-connected inverter.



Solar PV Panel Characterization

• Experiment: Recording characteristics• In this experiment, we measure the solar module’s V/I

characteristic at various irradiances.

3 panels (emulators) can be connected in series or parallel

V

I



Features• Rotor with three blades• Wind vane• Generator (permanent magnet

synchronous generator)• Rectifier• Slip-rings• Charge regulator or controller• Rechargeable storage battery• Inverter

Lab setup for experimenting with small wind technology



Simple experiments at varying speeds

Objectives

• To understand the relationship between wind speed and generator power

• Exercise - Determine the generator's maximum power at wind speeds of 8, 10 and 12 m/s.– Verify that the relationship between maximum

generator power and wind speed is cubic– Verify that the load must be adjusted according to the

wind speed in order to maximize the generator power



Lab setup for experimenting with grid-tied wind technology

Features• Wind emulator

• 1 kVA DFIG unit with two controlled inverters

• Emulation of wind and airfoil geometry

• Adjustable blade pitch

• Manual and automatic synchronization.

• Automatic control of active and apparent power, frequency and voltage



Speed-dependent power control characteristic

Wind power characteristics (red)Theoretical curve (green )Control characteristic (blue)



Experiment goals• Effects of pitch angle adjustment

– Operate the WT at varying wind speeds

• WT’s dynamic response in the partial load range– Determine the influence of load on speed– Determine optimal operating points for the

generator

Large wind power plant experiments



Learning about the smart grid

• Generation coordination• Automation (sensors, controllers and

communication equipment)• Smart metering• Microgrid control• Demand response



Smart grid setup

Features:• Smart meters SCADA Remote sensing units• Protection relays PV emulator Wind emulator• Energy storage Inverters Conventional

generation• Flexible loads



Conclusion

• Student class projects• Senior design projects• Class demo• Lab currently serving two courses (power

systems, motors and drives)• Will be used to design a 1-hour lab course in

advanced topics in power (renewable energy, smart grid, distribution automation, etc.)

Date post:	26-Mar-2018
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