What is power quality?
The IEC (1000-2-2/4) standard defines power quality as follows: power quality refers to the physical characteristics of power supply devices that do not interrupt or interfere with users' use of power under normal working conditions. The most serious power quality problems are voltage sags and complete voltage interruptions.
In fact, power quality refers to the quality of power system. Like seeds, there is a quality problem with the electric energy we use at ordinary times. High quality electric energy can not only reduce the loss of electrical appliances and improve the efficiency of the use of electric energy, but also can ensure the stable and healthy operation of the power system. Hospitals, data centers and other industries that pay special attention to power supply safety have high requirements for power quality.
What causes power quality problems?
In a broad sense, the factors affecting power quality mainly include three aspects:
1. The impact of natural factors such as lightning strike, storm, rain and snow on power quality causes accidents in the power grid and reduces the reliability of power supply.
2. The starting and stopping of large power equipment, tripping and reclosing of automatic switches and other automatic protection of power equipment and devices and the impact of normal operation on power quality temporarily reduce the rated voltage, generate fluctuations and flickers.
3. The extensive use of nonlinear load and impact load, such as the impact of steelmaking electric arc furnace and electrified locomotive operation on power quality, causes a large number of harmonic interference, voltage disturbance, voltage fluctuation and flicker in the public power grid.
Classification of power quality problems
If classified according to different characteristics in time domain, power quality can be divided into two types: steady-state power quality and transient power quality problems.
Steady state power quality problem: the continuity of steady state outstanding time refers to the periodic distortion of voltage and current waveform in a long time. This kind of power quality problems mainly include: overvoltage and undervoltage, voltage imbalance, harmonic and other problems.
Transient power quality problem: large voltage change and impact amplitude in a short time. It mainly includes: voltage flicker, voltage surge, voltage dip (drop), voltage interruption, etc. Among them, voltage sags and voltage interruptions are the most serious.
Power quality problems can also be classified according to voltage quality and current quality. The contents of voltage quality are shown in Figure 1 below.
Fig.1 Voltage quality |
The content of current quality is shown in Figure 2 below, which mainly refers to the current distortion caused by nonlinear loads such as power electronic equipment.
Fig.2 Current quality |
Among the power quality problems, the following seven aspects are mainly considered: voltage quality: voltage deviation, voltage flicker and fluctuation, voltage sag and interruption, and frequency deviation; Current quality includes harmonic and interharmonic, three-phase imbalance and low power factor.
Yingtong Electric Power Quality Solution
Yingtong Electric has focused on the field of power quality for more than ten years, mainly providing Static Var Generator and Active Harmonic Filter products, and is committed to solving the harmonic problem in the field of reactive power compensation. Yingtong Electric's modules own excellent performance and high cost performance.
Projects( Some examples) |
Products |
Model |
Johnson Road Traffic Card Data Center Project |
YTPQC-SVG |
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YTPQC-AHF |
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China Electronics Technology Group Corporation The 50th Research Institute |
Active Harmonic Filter |
YTPQC-AHF |
Huaye International Data Center Project |
Active Harmonic Filter |
YTPQC-AHF |
China Unicom Cloud Computing Service Data Center Power Distribution Project |
Active Harmonic Filter |
YTPQC-AHF |
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