1 Introduction
In order to improve the level of medical services, new and complex advanced medical equipment such as nuclear magnetic resonance, CT scanners, X-ray machines, and hemodialysis machines have been continuously introduced, and various energy-saving lighting equipment, inverter air conditioners, and elevator equipment have been put into use. These devices are non-linear devices that generate a large number of high-order harmonics during operation, causing some interference to the power distribution system and medical equipment. At the same time, these advanced medical devices have high-end computer components and a large number of high-sensitivity microelectronic devices. They have high requirements on the power quality of the power supply, and are very sensitive to voltage fluctuations and harmonics of the power. Severe power harmonic problems can cause medical problems. Damage to equipment can even lead to medical accidents.
2 Harmonic Source, Harmonic Characteristics and Harm Harm Analysis of Hospital Building Power Supply System
2.1 Sources of Harmonics
Main classification
Facility equipment name
Building facilities
Elevator equipment
central aircon system
Fire pump
lighting device
Medical Facilities
Operating room, laminar flow system
ICU, delivery room, neonatal care unit, hemodialysis center, etc.
Preparations, samples, blood preservation and freezing facilities
Hospital office automation facilities
Medical diagnostic equipment
The main diagnostic equipment, such as spiral CT machine, color Doppler, nuclear magnetic resonance apparatus, laparoscope, electroencephalogram machine, chromatograph, various function detection instruments, etc.
The main treatment equipment, such as ventilator, hyperbaric oxygen chamber, various monitors, laser therapeutic apparatus, etc.
2.2 Characteristics of Harmonics
Harmonic source load type
Harmonic current times
Harmonic current distortion rate
Lighting fixtures, computers, etc.
3,5,7,9, etc. (2n+1) times
(7~10)%
Electronic detection equipment, operating room, gamma knife, etc.
3,5,7,9, etc. (2n+1) times
(10~15)%
CT, magnetic resonance, DSA, etc.
3,5,7,9, etc. (2n+1) times
(30~40)%
Accelerators, X-ray machines, gastrointestinal machines, etc.
3,5,7,9, etc. (2n+1) times
(50~60)%
UPS, variable frequency ventilation equipment, elevators, etc.
5, 7, 9, 11 etc. (6n + 1) times
(25~35)%
2.3 Harmonic hazard analysis
2.3.1 Harmonic Harm to Distribution System
Increase the additional loss of power components and cause fire; affect the normal operation of electrical equipment; cause grid resonance; make relay protection malfunction, electrical measurement error is too large; so that the industrial control system crashes.
2.3.2 Harmonic harm to medical equipment
Loss of synchronization and data errors caused by devices that rely on microprocessor technology; directly endanger the safety of internal electronic circuits of devices, resulting in breakdown or discharge; and affect the performance and accuracy of precision medical devices.
3 National standards for power grid harmonics
The currently adopted power quality (harmonic) assessment standards are mainly China's national standard “Power Quality: Harmonics in the Public Power Grid†(GB/T14549-1993). The standards stipulate clearly the current and voltage distortion rate in the power grid, and also serve as Harmonic evaluation, an important basis for governance.
Table 1: National Harmonics Voltage Standards for Power Grids: Quoted in (GB/T14549-1993)
Grid nominal voltage (kV)
Total harmonic distortion (%)
Each harmonic voltage content (%)
Odd times
Even
0.38
5.0
4.0
2.0
6
4.0
3.2
1.6
10
35
3.0
2.4
1.2
66
110
2.0
1.6
0.8
Table 2: Allowable values ​​of harmonic currents injected into the common connection point of the grid: cited in (GB/T14549-1993)
Nominal electricity
Pressure (kV)
Short circuit
Capacity (MV.A)
Harmonic Times and Permissible Harmonic Current (A)
2
3
4
5
6
7
8
9
10
11
12
13
0.38
10
78
62
39
62
26
44
19
twenty one
16
28
13
twenty four
10
100
26
20
13
20
8.5
15
6.4
6.8
5.1
9.3
4.3
7.9
14
15
16
17
18
19
20
twenty one
twenty two
twenty three
twenty four
25
0.38
10
11
12
9.7
18
8.6
16
7.8
8.9
7.1
14
6.5
12
10
100
3.7
4.1
3.2
6
2.8
5.4
2.6
2.9
2.3
4.5
2.1
4.1
4 ANAPF low voltage active filter application in hospital building
4.1 Introduction to Active Filter Applications
The newly-built outpatient inpatient complex of a large-scale top-three hospital has a total of four 2000kVA and one 1600kVA transformers and one 800kW diesel generator, according to the load rate of the transformer's non-linear load equipment and the corresponding harmonic distortion rate. The harmonic currents are calculated using the simultaneous use rate of each nonlinear device, and five ANAPF active filters with different capacity specifications are configured.
The following is a detailed description of the comparative analysis of the power quality test conditions of the distribution system before and after the operation of the 1# ANAPF active filter. The load of 1# transformer is mainly lighting, elevators, submersible sewage pumps, and computer centers.
4.1.1 Data before and after the active filter is put into operation
(1) The distortion of the current waveform before the input of the active power filter is serious. The harmonic content of the three-phase current is respectively 19.7%, 27.8%, and 26.6%. The three-phase currents are 45A, 40A, and 64A, and the neutral current is 37A.
(2) The distortion of the current waveform after the input of the active filter is significantly improved, and the harmonic content of the three-phase current is significantly reduced, which is 2.9%, 2.8%, and 3.4%, and the three-phase currents are 47A, 48A, and 47A, respectively. The current is 5A.
(3) The current waveform is significantly improved. After the filter is used, the current waveform is approximately in the form of a sinusoidal wave. Harmonic control work has achieved the desired goal and effect.
4.1.2 Test Record Data Before and After the Active Filter Is Put into Operation
    Â
4.2 The significance of active filter application in hospital buildings
Protecting the safety of medical electrical equipment, purifying the power supply, protecting the power factor compensation equipment, preventing the malfunction of the protection device, reducing the power consumption, and expanding the power supply capacity of the transformer and the generator.
4.3 Active Filter Main Specifications
Wiring
Three-phase three-wire or three-phase four-wire
Access voltage
3×380V ±10%
Access frequency
50Hz ±2%
Dynamic compensation response time
Dynamic response <4ms, full response time <20ms;
On-off level
10kHz
Function settings
Only harmonics are compensated, only reactive power is compensated, both harmonics are compensated and reactive power is compensated; manual and automatic switching are performed.
Harmonic compensation times
2-21 times
Type of protection
DC over-voltage IGBT over-current device temperature protection
Overload protection
Automatic current limit in the set value, no overload occurs
cooling method
Smart air cooling
noise
< 65db (in the cabinet and operating in the rated state)
Working temperature
-10°C to +45°C
Working environment humidity
<85%RH non-condensing
Installation occasion
Indoor installation
Altitude
≤1000m (for use at higher altitudes)
Incoming and outgoing ways
Down in and out
Protection level
IP21
Intelligent communication interface
RS485/MODBUS-RTU
Remote monitoring
Optional
Overall size (mm)
(W×D×H)
30A
50A
75A
100A
600×500×1500
600×500×1500
600×500×1800
800×600×2200
Weight (kg)
Three-phase four-wire
Three-phase three-wire
30A, 50A
75A, 100A
30A, 50A
75A, 100A
280
360
240
290
4.4 Active Filter Quotation and Component List
Model Number: ANAPF100-400/B
Reference price: 120,000 yuan/set
The main product details:
No.
Name
Model number
Quantity
1
APF electrical cabinet
800X600X2200
1
2
Converter
APFCOV-CVT100
1
3
Controller
APFMC-C100
1
4
Reactor
APF-RE.(S)DG-100
1
5
Active current transformer
LT208-S7
3
6
filter
DL-1TH1
2
7
breaker
CVS160FTM160D4P3D
1
8
Contactor
LC1D150M7C
1
9
MCB
NDM1-63C32
1
10
Intermediate relay
MY4NAC
2
11
R type transformer
R320-0.38/0.22
1
12
Harmonic Detector
ACR350EGH
1
13
wire
16mm2
Some
14
wire
4mm2
Some
5 Conclusion
This article analyzes the harmonic source, harmonic characteristics and hazards of hospital buildings, and compares the situation before and after active power filter input and application through active filter applications in a low-voltage distribution system of a large hospital. Harmonic filter control technology is one of the effective means to improve the power quality of the power supply. The generated harmonics can be controlled within the minimum range to achieve scientific and rational use of electricity, inhibit power grid pollution, improve power quality, and ensure the safety of medical equipment. .
ã€references】
[1] GB/T 14549-1993 "Power Quality: Harmonics in Public Grids"
[2] Shanghai Ankerui Electric Co., Ltd. Product Manual. 2013.01.
[3] doc88.com "" hospital industry "distribution system harmonic control case"
Rubber Pad,Black Railway Rubber Pad,High-Elastic Rail Pads,Rubber Pad For Railway
Anyang Railway Equipment CO.,Ltd , https://www.ayrailwayat.com