Learn what is power quality in one article.

What is power quality?

The issue of power quality has been raised for a long time. In the early days of the development of the power system, the composition of electric loads was relatively simple, mainly composed of linear loads such as synchronous motors, asynchronous motors, and various lighting equipment. Therefore, the indicators for measuring power quality were also relatively simple. There are mainly two types: frequency offset and voltage offset. Since the 1980s, with the development of power electronics technology, nonlinear power electronic devices and devices have been widely used in modern industry. At the same time, to solve the problems existing in the development of the power system itself, DC transmission and FACTS technologies are continuously put into practical engineering applications, and speed-regulating motors and reactive power compensation capacitors are also put into operation in large numbers. The operation of these devices causes the voltage and current waveform distortion in the power grid to become more and more serious, and the harmonic levels continue to rise. In addition, impact and fluctuating loads, such as electric arc furnaces, large rolling mills, electric locomotives, etc., will not only generate a large number of high-order harmonics during operation, but will also produce power quality such as voltage fluctuations, flicker, and three-phase unbalance. question. But on the other hand, as various complex, sophisticated, and sensitive electrical equipment that are sensitive to power quality continue to spread, people have higher and higher requirements for power quality, so power quality has become a hot spot in current research.

Characteristics of power quality

Power production companies cannot completely control power quality. Some changes in power quality are caused by power users (for example, harmonics, voltage fluctuations flickers, etc.), or caused by natural disasters and uncontrollable factors.

The power indicators of power supply and consumption at different times are usually different because the power quality is constantly changing in space and time.

The main hazards of power harmonics

1. Cause series resonance and parallel resonance, amplify harmonics, and cause dangerous overvoltage or overcurrent;

2. Generate harmonic losses, reducing the efficiency of power generation, transformation, and electrical equipment;

3. Accelerate the aging of the insulation of electrical equipment, making it easy to break, thereby shortening its service life;

4. Cause equipment (such as motors, relay protection, automatic devices, measuring instruments, power electronic devices, computer systems, precision instruments, etc.) to operate abnormally or fail to operate correctly;

5. Interfering with the communication system, reduces the transmission quality of the signal, destroys the correct transmission of the signal, and even damages the communication equipment.

Methods to control power harmonics

There are three main harmonic control measures: one is active control, that is, starting from the harmonic source itself, by improving the electrical equipment so that it does not produce fewer harmonics; the other is the receiving end control, that is, starting from the harmonics affected Starting from equipment or systems, improve their ability to resist harmonic interference; the third is passive management, that is, by installing power filters to prevent harmonics generated by harmonic sources from being injected into the power grid, or to prevent harmonics from the power system from flowing into the load end.

Due to the extensiveness and complexity of harmonic sources, active treatment methods are affected by factors such as equipment structure, efficiency, cost, reliability, etc., and can only solve part of the problem. The receiving-end treatment methods and passive treatment methods are still the current treatment methods for power harmonic problems. main method. For example, series detuned reactors are used to suppress harmonic resonance amplification caused by reactive power compensation capacitors, and passive power filters and active power filters are installed in the system for filtering, etc.

RDCR5000 power quality tester

Dual-Processor Architecture

The analyzer adopts a DSP + ARM dual-processor architecture. DSP handles data collection and algorithm processing, while ARM manages communication protocols and interface processing.

Analog Signal Acquisition

Analog signal acquisition utilizes two AD7655 chips from ADI. These chips offer 16-bit resolution and synchronous sampling across four channels. With a maximum sampling rate of 1 MSPS, they ensure precise channel accuracy and information integrity.

High-Frequency DSP Operation

The DSP operates at a frequency exceeding 200 MHz. This enables real-time monitoring of the power grid and dynamic adjustment of the sampling frequency to synchronize with the power frequency.

Color LCD Display

Equipped with a 5.6-inch LCD color screen displaying at 640 x 480 resolution, the analyzer provides clear differentiation in parameter displays. Users can efficiently and intuitively understand the power grid status through displays of phase, waveform, vector diagram, and harmonic ratio.

Internal Memory Storage

The device features internal flash memory for storing various data types. It can accommodate storage for 60 sets of screenshots, 150 sets of transient voltage/current waveform capture, and 12800 sets of alarm logs. Additionally, it allows continuous capture of starting current waveforms for up to 100 seconds.

Trend Curve Record

A built-in 2GB memory card enables storage of trend curve records. It captures data for 20 parameters at five-second intervals, with the option to choose parameters based on requirements. Trend curve records can be retained for up to 300 days.