KoCoS Blog

Monitoring power quality (PQ) in the distribution system is an important task for energy suppliers and their customers. In a distribution system, various types of faults cause power quality disturbances. Power supply operation can be improved and maintained by systematically analyzing power quality disturbances.
The power supply is designed to operate with a sinusoidal voltage at a constant frequency. Power quality disturbances occur when the magnitude of the voltage, frequency, and/or waveform deviation change significantly due to various types of faults such as nonlinear loads, switching of loads, weather conditions, etc.
The effects of poor power quality depend on the duration, magnitude, and sensitivity of the connected equipment. Poor power quality can lead to process interruptions, loss of data, malfunction of computer-controlled equipment and overheating of electrical equipment.
It is important to detect and classify power quality disturbances. A variety of waveforms can be generated by simulations and be useful for disturbance detection and classification.
The waveforms of the possible disturbances are created in this description by mathematical models. The EPOS 360 three-phase signal generator and EPOS operating software are available for modeling and generating signals to analyze the events in the power system.

Ideal voltage/current source
An ideal AC voltage source generates a continuous, smooth sinusoidal voltage.

Voltage fluctuations
A drop (undervoltage, voltage dips) or rise (overvoltage, swell) of the mains voltage of at least ½ cycle up to several seconds.

Voltage interruptions
A significant or complete voltage interruption. The interruption can be short-term but also permanent.
 

Harmonics
Distortion of voltage and current waveforms caused, for example, by operation of nonlinear loads.

Transients
A sudden disturbance in the line voltage that typically lasts less than one period and consequently the waveform becomes discontinuous.

EPOS CV voltage sources provide both a high output voltage and a high output current. Especially when operating motors, large starting currents occur when the full rated voltage is applied, which can be many times the rated currents. The voltage sources are capable of supplying these current peaks up to 10 times the rated current of the load during the switch-on process.

In the real power supply environment, it is difficult to generate power quality events in order to analyze their characteristics and effects. Therefore, a system is needed with the ability to generate and output diverse three-phase signal waveforms.

With the software-based signal generator system EPOS 360, it is possible to realize an overall system with which three-phase power quality events can be simulated in a simple way.
Three-phase voltage and current signals with different signal disturbances can be generated with the EPOS operating software, such as voltage dips or interruptions, transient pulses and distortion of the voltage or current signal caused by the influence of higher order harmonic components.

Different monitors are available in the software for parameterization and the output of signals and test sequences.

TRANSIG-Monitor

The TRANSIG-Monitor module can be used to check the function of a DUT under real conditions. The TRANSIG-Monitor enables the graphical display and output of recordings and signal curves. Signal curves can be, for example, recordings of fault value acquisition systems or digital protection relays, which are available in the standardized COMTRADE format, or SigDef files with self-defined signals.

The functions of the TRANSIG monitor are:

1. Loading of recordings in COMTRADE format or SigDef files.
2. Assignment of the signals of the recording to the EPOS output signals.
3. Scaling of the signals of the recordings.
4. Transfer of the defined TRANSIG functions into a test plan.

Signal Editor

Another component of the EPOS operating software is the signal editor. The signal editor enables the definition, parameterization and calculation of any signal characteristics. The parameterization of the signals is done interactively on the screen. A signal duration can be set for each channel and each channel can in turn be divided into any number of time windows of different lengths. Within the time windows different function curves can be synthesized. It is possible to synthesize the function curves from a basic function, such as

1. sine, 
2. rectangle, 
3. sawtooth,
4. triangle, 
5. DC

and their additive or multiplicative superposition with one or more superposition functions.

Superpositions can be functions, such as

1. sine,
2. exponential functions,
3. ramps,
4. DC,
5. impulse,
6. harmonics,
7. mathematical expressions.

In particular, the mathematical expressions in the overlays should be pointed out, since the creation of formulas offers a wide range of possibilities for signal generation. The overlay function "Expression" is used to create a curve using mathematical inputs.

Conclusion

The three-phase signal generator EPOS 360 offers the possibility to create different signal waveforms, to apply them to the test object and to analyze the effects. The overall EPOS 360 system with the EPOS operating software thus provides a useful mechanism to understand and explain network phenomena without much effort.

Do you have questions about the EPOS 360 three-phase signal generator? We have the answers!
Contact us via the comment function here on the blog or by mail to info(at)kocos.com.

Ohm published his results in 1826 and initially received little recognition. It was not until 1841 that Ohm received the Copley Medal of the Royal Society of London, which corresponds to today's Nobel Prize, as an award for his work. In 1893, the World Electrical Congress in Chicago gave the designation "Ohm" (sign Omega: Ω) to the unit of electrical resistance.

With Ohm's torsion balance galvanometer, only the first step in the development of resistance measuring instruments is described in this article. The history of resistance measurement shows the changes from the age of early experimenters to today's computer age, i.e. from measuring bridges to the first electronic devices to today's digital measuring systems. Developers always used the latest ideas and systems to make the products more useful and user-friendly. Technological change drove the development of measuring instruments and realized technological advances.