What is the fault characteristics of power systems?
In power systems, faults refer to abnormal conditions that occur due to equipment failures, environmental factors, or other disturbances. Faults can lead to disruptions in the electrical system, potentially causing equipment damage, system instability, or even blackouts. The fault characteristics in power systems include the following:
Transients: Transients are temporary disturbances characterized by sudden changes in electrical quantities such as voltage or current. They occur at the onset of a fault and can propagate through the system, affecting the voltage waveform shape and magnitude. Transients can be categorized into fast transients (nanoseconds to microseconds) and slow transients (milliseconds to seconds) depending on their duration.
Symmetrical Components: Faults in power systems can be analyzed using symmetrical components theory, which decomposes the system into three sets of balanced components: positive sequence, negative sequence, and zero sequence. Each component represents the behavior of the faulted system under different fault conditions. The magnitude and phase relationship of these components can indicate the type and location of the fault.
Harmonics: Faults can generate harmonics, which are integer multiples of the fundamental frequency (typically 50 Hz or 60 Hz). Harmonics can distort the voltage and current waveforms, causing additional stress on equipment or interference with communication systems. The presence of harmonics can be an indication of a fault in the power system.
Voltage and Current Dips/Sags: Faults can cause temporary reductions in the magnitude of voltage or current, commonly known as dips or sags. These events are characterized by a rapid decrease and subsequent recovery of voltage or current levels. The duration and extent of the dip/sag can vary depending on the fault type and location.
Unbalanced Conditions: Faults can lead to unbalanced conditions in power systems, where the distribution of voltage or current among the three phases becomes uneven. Unbalanced conditions can result from single-phase or phase-to-phase faults and can adversely affect the operation of connected equipment, such as motors or transformers.
Understanding the fault characteristics is crucial for fault detection, location, and system protection in power systems. Various techniques and protective devices are employed to detect and mitigate faults, ensuring the safe and reliable operation of the electrical grid.
What are power quality solutions of the fault characteristics in power grid?
It's important to note that the specific solutions implemented may vary depending on the characteristics of the power grid, the type of faults encountered, and the regulatory requirements in a particular region.
Shanghai Yingtong is a professional designer and manufacture of Power quality products, Active Harmonic Filter(AHF),Staitc Var Generator(SVG) and Advanced Static VAr Generator(ASVG).
YTPQC-AHF Active Harmonic Filter is a perfect and comprehensive solution to the power quality issues of power grid , such as harmonics, reactive power and 3 phase load unbalance. YTPQC-AHF which is in parallel to power grid can detect the harmonic wave in power grid in time, generate the reverse-phase compensation current through the converter and dynamically filter the harmonic wave in power grid.
Based on the principle of voltage source inverter, YTPQC-ASVG Advanced Static Var Generator uses insulated gate bipolar transistor (IGBT) to control the magnitude and phase of inverter AC voltage, so as to achieve the purpose of reactive power, harmonic and imbalance compensation. Because the switching frequency of IGBT is very high (up to 25.6kHz), ASVG can compensate rapid reactive loads and achieve quite high compensation accuracy. ASVG have the best cost performance with the function of reactive power and harmonics control.
YTPQC-SVG Static Var Generator detects load current in real time through internal and external CT and analyzes the reactive current of load by TI DSP and FPGA, then generates PWM signal to IGBT inverter(3 Level) to generate inductive or capacitive current and compensate reactive current to realize the target power factor. YTPQC SVG can also compensate phase imbalance.
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