Power Quality

ACTIVE HARMONICS FILTER

Model AHF

(Wall mount & Rack mount)

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

INTRODUCTION TO POWER QUALITY AND HARMONICS

■ 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.

Most common power quality problems:

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

■ 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.

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)

■ 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

■ 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)

■ 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

■ 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)

■ 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

In the electrical system there are many harmonic orders, the working principle in bar graph is shown as below.

Active harmonics filter bargraph

The process of AHF separating harmonics of and processing them as shown below:

Ilec Active harmonics filter working principle

■ ILEC AHF features

Harmonic compensation up to 50th order, 14 different harmonics at the same time
Fast reactive power compensation, support unbalance system
Load balancing between phases and unloaded neutral wire
Compact design, 3 level topology
Modular system extendable, support up to 6 modules for one HMI.
Grid resonance detection and prevention using hardware and software
Dual DSP+FPGA Architecture with leading algorithm, fast response

■ ILEC AHF Ordering code structure

ILEC AHF Current rating seclection table:

◾ILEC AHF Technical parameters

ITEM	400VAC system
Input voltage (VLL)	Un (-10% ~ +10%)
Grid type	3P3W (0.4/3L) / 3P4W (0.4/4L)
Grid frequency	50Hz / 60Hz (-10% ~ +10%)
Maximum parallel modules	6 modules per HMI controller / unlimited number of controller and modules
Overall efficiency	>= 97%
Current transformer	50/5A to 5000/5A (more range on request)
Circuit topology	Tri-level
Rated capacity	30A, 50A, 75A, 100A, 150A (check table 2.2 for update)
Filter functions	Harmonics filter / Reactive power compensation / Phase balance function
Filter harmonics order	2 ~ 50, maximum 14 orders (selectable) at the same time
Filter Amplitude adjustment	Maximum 150% for each order (Default recommended 80–90%)
Filter phase adjustment	2 to 50 degree
Filtering ability	THDi< 5%
Response time	< 15ms
Target power factor	-1 to 1 (Capacitive and Reactive) (Recommended -0.95 to -0.99 / 0.95 to 1.00)
kVAR compensator mode	support
Control algorithm	FFT, intelligent FFT algorithm, instantaneous reactive algorithm
Switching frequency	20kHz
Cooling mode	Forced air cooling (built-in fan)
Noise level	< 65dB
Communication interface	RS485, Ethernet (optional)
Communication protocol	Modbus-RTU
Monitoring mode	Support centralized monitoring and independent monitoring (optional)
Display interface	7, 10 inch centralized monitoring LCD touch screen, 4.3 inch independent
Protection function	Over voltage / under voltage protection, short circuit protection, inverter bridge reverse protection and overcompensation protection
Fault alarm	Yes, up to 256 alarm records
Fixed mode	Rack mounted type, wall-mounted type
Altitude	rated capacity for below 1500m, 1500–4000m: reduced by 1% every 100m
Operating temperature
Relative humidity	5% ~ 95%, no condensation
Protection class	IP20

CONNECTION DIAGRAM AND MODULAR DESIGN

■ Connection diagram

■ Modular design

EQUIPMENT DESCRIPTION

■ 0.4kV and 0.48kV AHF

Equipment introduction

No.	Name	Remark
1	Front panel	AHF Module front panel
2	Status indicator	Device running status display
3	Cooling fan	/
4	Handle	(only for rack-mounted AHF module)
5	Rack mounting ear	Rack-mounted module mounting fixed (Rack-mounted only)
6	Cooling duct	/
7	Main circuit input terminal	L1, L2, L3
8	Neutral input terminal	N²
9	Ground wire input terminal	PE
10	Current sampling input terminal	CT1/CT1N, CT2/CT2N, CT3/CT3N
11	Auxiliary circuit terminal	DC 24V auxiliary power supply, RS845 communication
12	DIP switch	Communication address setting
13	Cooling duct	/
14	Wall mounting ear	Wall-mounted module mounting fixed (Wall-mounted only)

■ 0.69kV AHF

Equipment introduction

No.	Name	Remark
1	Status indicator	Device running status display
2	Front panel	AHF Module front panel
3	Rack mounting ear	Rack-mounted module mounting and fixed
4	Handle	Rack-mounted AHF module front handle
5	Ground wire input terminal	PE
6	Neutral input terminal	N
7	Main circuit input terminal	L1, L2, L3
8	Upper cooling duct	Upper heat dissipation
9	Current sampling input terminal	CT1/CT1N, CT2/CT2N, CT3/CT3N
	Auxiliary circuit terminal	DC 24V auxiliary power supply, RS845 communication
	DIP switch	Communication address setting
10	DIP switch	Bottom fan

AHF MODULE DIMENSIONS

■ 0.4 kV AHF Module Dimensions

Wall-mounted design

0.4kV	Wall-mounted module dimension (Unit: mm)
0.4kV	30A / 50A	75A / 100A	150A
A	460	540	540
B	440	524	524
C	62	85	110
D	86	190	219
E	420	500	500
F	483	545	551
G	451	507	515
H	420	478	479
I	86	135	145