Regulated Power Supplies(RPS) for transducers : 12V DC Supply
1 Phase Autotransformer
Data Acquisition Card - NI 9239 and NI cDAQ 9184
Software:
National Instruments - LabVIEW 2012
What challenge/problem are you trying to solve through your application:
In recent years, power quality has become an important issue and is receiving increased attention from electrical utility experts and consumers. It covers a wide range of issues, from voltage disturbances like sag, swell, outages and transients, to current harmonics, performance wiring and grounding. Poor power quality affects the functioning of utilities, industrial units, productions, system performance, customer services and operating cost.
The symptoms of poor power quality include intermittent lock-ups and resets, corrupted data, premature equipment failure, overheating of components for no apparent cause, etc.
Also, a lot of research has been carried out on waveform distortion which forms an important aspect of power quality analysis. It occurs mainly due to harmonics, noise and impulsive transients. The ultimate cost is in downtime, decreased productivity and reduction of customer satisfaction. By knowing the exact amount of harmonics, noise and transient impulses etc., one can take appropriate steps to reduce their harmful effects and this forms the basis of this project.
How does your application solve the above mentioned challenge/problem:
Though analog meters and recorders are available for monitoring of some power quality parameters, continuous monitoring is practically difficult to implement. Also, with the increased usage of non-linear loads, harmonic analysis has become crucial. Moreover, it is all too common that different power quality problems can occur simultaneously, interchangeably or randomly. In order to understand the power quality problems better, comprehensive monitoring and data collection of power quality events are important. Monitoring systems serve as a vital diagnostic tool and help to identify the cause of power quality disturbances while making it possible to identify problem conditions before they cause interruptions or disturbances.
In this work,a technique has been presented and applied for the detection of various power quality parameters. It has been compared to existing methods. This technique has been extended further for voltage analysis.
The proposed model involves the implementation of different virtual instruments using a graphical programming language, here, LabVIEW - by way of software development and manipulation.
LabVIEW has extensive libraries of functions for data acquisition, instrument control, and data analysis. It can model standard laboratory instruments while offering more flexibility. This work presents a simple power quality monitoring method based on LabVIEW. The system based on virtual instruments not only detects power quality indices of the present power generation in real time, but also has some simple analysis functions.
Power quality parameters such as apparent, active and reactive power, power factor and harmonics are all presented. Observations of the system depict the importance of power quality monitoring and the precision of the developed system.
Description of Project:
In this work, a simple power quality monitoring system is developed by designing Virtual Instruments (VIs) using LabVIEW. Power quality parameters such as apparent, active and reactive power, power factor and harmonics are all presented. Observations of the system depict the importance of power quality monitoring and the precision of the developed system.
Also, a National Instruments Data Acquisition card is chosen to interface the analog AC signal as a second step after taking the input. These inputs to the system are conditioned before interfacing and this helps curb the loss of data and ensures simultaneous sampling. Sensors are used for measurement of single phase currents and voltages. Current probes and Hall Effect voltage sensors are employed to acquire voltage and current signals for proper and accurate sensing.
Using LabVIEW internal programs, different noises or disturbances are generated to view different events of power quality on simulated signals by the developed Virtual Power Analyzer. Then, the simulation blocks are replaced by Data Acquisition palettes. Waveforms of the different parameters are observed for various types of loads and values of power (active, reactive, apparent), power factor, Total Harmonic Distortion (THD) (%), and Signal-to-noise and distortion ratio (SINAD) (in decibels) are obtained. In addition to this, power quality indices such as sag, swell, and interruptions are also classified.
Thus, the work proposes the development of a computer-based power analyzer that provides real-time monitoring of various power quality parameters, with remote monitoring feature. The system runs on a desktop computer with National Instruments (NI) 9239 Data Acquisition (DAQ) card and cDAQ 9184 Chassis. The system is implemented as a virtual instrument (VI), whereby, a programming and user interface is developed using LabVIEWTM. The main objectives of the work are to capture power quality parameters and disturbance events and the storage of this data for post-monitoring analysis and corrections.
Thus, the target specifications are as follows:
1. Obtaining voltage, current and power waveforms, calculation of RMS values of voltage and current, power factor.
2. Plotting of the Amplitude vs. Frequency spectrum.
3. Apparent, Active and Reactive power calculations.
4. THD in the system (%), SINAD in dB, Harmonic content in the spectrum.
5. Classification of power quality events such as sag, swell and interruptions.
Also, the system can continuously measure voltage and current on a cycle-by-cycle basis and using MS- Excel, it is possible to log time, date and duration of the various power quality events. Since the DAQ used functions on an Ethernet Chassis, remote sensing is achieved.
