1) When pure capacitors are used for compensation, if the system contains harmonic components, they will form a parallel resonance point with the system, which may lead to harmonic parallel resonance.

2) Connecting a reactor in series at the front end of the capacitor can effectively shift the parallel resonance point away from the characteristic harmonics of the load. In addition, it can also suppress the magnitude of the inrush current when the capacitor is switched on.

1)The load harmonic components can be measured by using a power quality analyzer.

2)The selection of reactance rate depends on the lowest-order harmonics generated by the load and the harmonic content, which can effectively avoid system parallel resonance.

For 3rd harmonics – reactors with 14.8% reactance rate are recommended

For 5th harmonics – reactors with 6% or 7% reactance rate are recommended

1) Impacts on the system

Formation of system parallel resonance points

Occurrence of harmonic parallel resonance

Induction of harmonic amplification, increasing the system voltage distortion rate

2) Impacts on capacitors

Causing overvoltage and overcurrent of capacitors

Increasing additional power losses of capacitors

Raising the operating temperature of capacitors

Accelerating capacitor degradation

Damaging the internal insulation performance of capacitors

Shortening the service life of capacitors

1) For rapidly varying loads – Thyristor Switched Switches (TSS)

Load equipment features intermittent operation cycles

Load equipment operates with rapid variations

2) For stable loads – Magnetic contactors

Load runs stably and continuously

Select appropriate equipment to mitigate harmonics.

1) Adopt high-precision and high-efficiency DSP and FPGA signal processors

2) Equipped with a high-reliability IGBT protection architecture

3) User-friendly graphical Human-Machine Interface (HMI)

4) Support both 3-wire and 4-wire compatible architectures

5) Provide multiple compensation functions

Three-phase load current balancing function

Independent compensation of odd and even harmonics

Harmonic mitigation up to the 50th order

Open-loop/closed-loop compensation architecture

6) Multiple harmonic filtering modes

Full-order harmonic filtering

Full-order harmonic filtering without fundamental reactive power compensation

Fundamental reactive power compensation only

Selective harmonic compensation

7) Built-in power metering and data logging functions

8) Support TCP/IP communication protocol for remote monitoring

Passive Harmonic Filters

Applicable occasions

1. Systems with variable frequency drives
2. Steel rolling mills
3. Electric arc furnaces
4. Functions
5. Filter out harmonics
6. Improve power factor

1) Passive 3rd Harmonic Filters

1. Applied in three-phase four-wire power distribution systems
2. Provide a low-impedance path between phases and the neutral line
3. Mitigate harmonic currents in phases and the neutral line
4. Provide reactive power compensation

2) Applicable places

1. Hospitals
2. Commercial office buildings

1) Increase power factor rebate fees

1. Power factor rebate fees from power supply bureaus
2. If the power factor is lower than 0.90, an additional surcharge will be imposed on the monthly electricity bill
3. If the power factor is higher than 0.90, the monthly electricity bill can be reduced

2) Improve the effective utilization rate of transformers

3) Reduce the apparent current of the power system

4) Decrease the power losses of system lines and transformers

5) Mitigate the voltage drop at the end of lines

6) Stabilize the supply voltage of the power system