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The basic principle of SVG (Static Var Generator also known as STATCOM) is that bridge circuit is connected to power grid by reactor or directly connected to network (as follows figure), proper adjustment of phase and amplitude in AC side output voltage of bridge circuit, or directly control AC side current, so that circuit is absorbed or emitted to meet the requirements of reactive current, to achieve the purpose of dynamic reactive power compensation.
1、Principle introduce
The cascade of SVG will be in the 6kV-35kV grid by H bridge stage variable flow circuit through the shunt reactor (or directly parallel). In order to adjust phase and amplitude of AC side output voltage in bridge converter circuit and control AC side current directly, the circuit can absorb or emit reactive current to meet the requirements, so as to achieve the purpose of dynamic reactive power compensation. |
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2、Technical features
>>Faster response
Response time of SVG:≤5ms.
SVG can complete from rated capacitive reactive power to rated emotional power conversion within a very short period, unparalleled in response speed can be competent on impact load compensation.
>>Higher security
SVG is controlled as current source, without possibility of resonance with system impedance and safety is higher.
>>Diversification of compensation function
Using the same set of SVG devices:
•Reactive power compensation；
•Compensated load harmonics；
•Unbalanced compensation；
•At the same time compensation of reactive power, harmonics and imbalance.
>>Low harmonic content
By using multiple control techniques, high frequency and low pulse, and output current harmonic content is small.
>>Smaller area
Reactive power compensation using PWM mode, exclude large capacity of parallel capacitor and floor space is small.
3、System composition
System is composed of starting cabinet, power cabinet and the control cabinet.
>>Starting cabinet
Connected compose of parallel in connect electric reactor and soft starting circuit, main realization of SVG system and power grid connection, reduce system to start impact of power grid and protection of system.
>>Power cabinet
Power cabinet is mainly composed of cascaded power module unit to achieve power conversion.
① The power module unit is H bridge structure, which has independent generatrix capacitance.
② Selection of imported high quality components with sufficient voltage and current margin.
③ Use the forced air cooling, with temperature and humidity control and other functions to enhance environmental adaptability of system.
④ Has the protection function of door detection improves security of system.
>>Control cabinet
Using UPS power supply, and equipped with dual power redundancy power supply technology to ensure the reliability of power supply system.
The controller adopts advanced industrial grade dual core floating point processor, and has ability to realize full digital high precision control of system.
The controller has powerful communication processing and monitoring function, providing support for remote monitoring and centralized control of system. And it supports remote control software, convenient Ethernet interface, which is convenient for centralized control of network.
Controller can display working state of system, operation data, current and voltage wave forms, with high resolution fault recorders.
Man-machine interface of color touch screen and easy to operate. User can set local parameters according to service situation to achieve different application occasions of compensation or reactive power source.
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4、Major function
For power system reactive power to fast dynamic compensation, matters are as follows:
•Power factor correction for dynamic reactive power load;
•Regulating system voltage;
•Improve static and dynamic stability of power system;
•Reduce voltage flicker and stabilize system voltage;
•Damped oscillation;
•Reduce voltage and current imbalance.
AC input
AC IN |
Rated voltage |
6kV/10kV/35kV |
| Rated frequency |
50x(1 ±5%)Hz |
| Mode of connection |
Three phase three wire |
| Target power factor |
Reach set requirements in capacity |
| Full response time |
5ms (10%-90%) |
| Active power loss |
Rated power <0.8% |
| Environmental
condition |
Working temperature |
-10℃ ～+45℃ |
| Storage temperature |
-20℃～+65℃ |
| Relative humidity |
<90% (在25℃ 时） |
| Work pattern |
Constant power factor, constant reactive power and constant voltage control |
| Communication interface |
Remote RS485/ Ethernet commun丨cation with optional and PC connmunications software optional |
| Operation display |
Operating parameters settings, touch button operation, multi parameter display, data records, ancient war taped, parameters and recorded data backup, remote control and parameter download and software controller remote update. |
| Display accuracy |
±2%FS |
| Expansion ability |
Parallel operation and satisfy more large capacity |
| Protection |
The power network is under voltage, the power grid is in the wrong phase, the device is over current, the device is overheated, the DC bus is over and over and the power module is over protected. |
6、Demonstration of type
7、Technical parameters
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Model
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Rated capacity(kvar)
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Width （mm)
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Depth（mm)
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Height（mm)
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AN-SVG-C-2000/6
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2000
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7000
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1200
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2400
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AN-SVG-C-3000/6
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3000
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7000
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1200
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2400
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AN-SVG-C-5000/6
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5000
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7000
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1600
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2400
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AN-SVG-C-7000/6
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7000
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7000
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1600
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2400
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AN-SVG-C-9000/6
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9000
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11000
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1600
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2400
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AN-SVG-C-2000/10
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2000
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7000
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1200
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2400
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AN-SVG-C-3000/10
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3000
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7000
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1200
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2400
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AN-SVG-C-4000/10
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4000
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7000
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1200
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2400
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AN-SVG-C-5000/10
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5000
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7000
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1200
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2400
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AN-SVG-C-6000/10
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6000
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7000
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1200
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2400
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AN-SVG-C-8000/10
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8000
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7000
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1600
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2400
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AN-SVG-C-10000/10
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10000
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7000
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1600
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2400
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AN-SVG-C-12000/10
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12000
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7000
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1600
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2400
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AN-SVG-C-15000/10
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15000
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11000
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1600
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2400
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It will use depressurization mode to 10kV mode when voltage level exceed 35kV, and its sharp refer to the same capacity of product, also transformer form can refer to same capacity with the same voltage grade power transformer.
Photovoltaic power generation field
Photovoltaic power generation applications are becoming more and more popular with the country's attention to new energy. Due to time-varying characteristics and change of load lead in system voltage fluctuation when PV power generation system and power grid connection, voltage of system must be adjusted with reactive power compensation device and system voltage adjustment device.
Electric power system
In power grid, power factor is improved by adopting capacitor compensation methodand line loss is reduced. Capacitance compensation can only provide capacitive reactive power, and compensation is not continuous, easily lead to non merits and demerits of fill, caused by voltage elevation, harm with electrical equipment safety and stability of power supply system.
Metallurgical field
LCD industry has a large number of electric arc furnace and other load, reactive power generated during work will cause power grid fluctuations and flicker, causing no power penalty, other electrical equipment can not work normally when its serious, reduce production efficiency, at the same time load big harmonic current will make power grid voltage distortion is serious and power supply system security caused great harm. Traditional way of capacitance compensation, on emergence of reactive power and harmonic problem has certain inhibition, merely effect is often limited, even up to counter, resulting in no merit compensation and harmonic amplification.
Rail transit
With rapid development of urban rail transportation industry, development of railway transportation industry is growing rapidly, current line is applied more and more widely, voltage level is gradually increased, line length is longer and capacity of cable line is caused by protection of circuit breaker.
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