Power Quality Product and Solution

Power Quality: Active Harmonics Filter (AHF), Static Var Generator (SVG), Current Imbalance Solution, Voltage sag and voltage corruption solution, Transformer balance solution.

1.INTRODUCTION TO POWER QUALITY AND HARMONICS

ILEC active harmonics filter

1.1 Electrical Power Quality

Electrical Power quality is any abnormal behavior on a power system arising in the form of voltage or current, which affects the normal operation of electrical or electronic equipment.

Power quality is any deviation of the voltage or current waveform from its normal sinusoidal wave shape.

Power quality has been defined as the parameters of the voltage that affect the customer’s supersensitive equipment.

Voltage sag
Voltage swell
Voltage Flicker
Harmonics
Over voltage
Under voltage
Transients

1.2. Ideal waveform and harmonics waveform

Most automation devices and internet devices use electricity. For these devices to operate stably, the quality of electricity must be guaranteed.

Power quality is best when both voltage and current have ideal sine waveforms.

Sine wave ensures that the voltage and current values vary evenly and are not too sudden. The slow and steady change helps components and equipment operate stably and durably.

Ideal sine wave

However, many new generation electrical devices cause power quality problems. These devices are often referred to as non-linear loads. Examples include controlled rectifiers, inverters, and switching power supplies.

Each type of equipment usually generates harmonics with different frequencies. Usually these frequencies are multiples of the fundamental harmonic. For example, the 1st order fundamental wave has a frequency of 50Hz, common wave frequencies are usually 150Hz (3rd order), 250Hz (5th order), 350Hz (7th order), 550Hz (11th order), 650Hz (13th order)

harmonics waveform

1.3. Common phenomenon caused by harmonics problems

Power capacitor overheat fault
Solar inverter restarts many times even though voltage is within allowable range
PLC jump or reset without reason
Abnormal action of circuit breaker and variable speed drive
Rising of equipment failure rate
Neutral cable overheat and big current even though line currents are balance
Precision instruments cannot work properly or are damaged
Overheat damage of equipment such as motor and transformer (not in overload condition)
The life of motor is shortened
Equipment can not reach the rated power, and the efficiency is low
Too high switchgear temperature rise and noisy
Sudden shutdown of the running inverter.
Precision instruments cannot work properly or are damaged

1.4. Benefits of harmonic treatment to improve power quality

Meet the requirements of power supply department on power consumption.
Reduce the economic losses caused by equipment misoperation.
Improve the efficiency and reliability of equipment operation.
Reduce heating of electric equipment, prolong insulation aging time
Increase service life of equipment, and reduce maintenance cost of equipment
Reduce the resonance probability of compensation capacitors in the power grid
Reduce the electromagnetic interference caused by harmonic
Improve the stability of small current systems (sensitive systems)

1.5. Benefits of power factor improvement (VAR correction)

Ensure the power factor of the system up to the national standard
Reduce grid line losses and improve upstream transformer capacity
Reduce the current and voltage drop, release the capacity of transformer and generator
Improve the utilization rate of equipment and improve the stability of power grid

1.6. Three-phase imbalance correction

Reduce neutral current caused by imbalance load and prevent fire risk;
Reduce voltage imbalance faults, reduce overload and overheat of transformer’s coil

ILEC ACTIVE HARMONICS FILTER (AHF)

2.1 AHF working principle

When an ideal sine source suply to a linear load, The current waveforms are sine both sides.

Ideal sine supply to no harmonics load

When an ideal sine source suply to a none-linear load, The harmonics current from load will distort the total current.

Harmonics load current flow

The active power filter monitors the load current real-time through the external current transformer CT, and extracts the harmonic component of the load current through the internal DSP computing, then sends it through the PWM signal to the internal IGBT, the inverter produces a current equal to the load harmonic and opposite to the harmonic direction and injects the current into the grid to compensate the harmonic current realizing the function of harmonic control.

active harmonics filter current flow