1, an overview
As the next generation of SVC products, SVG in response speed and stable power voltage, reduce the loss of the system, increase the transmission capacity, improve the transient voltage limit, reduce harmonics and decrease the area and other aspects of performance is more advantage.
2, working principle
The turn off of power electronic devices (such as IGBT) to form a self commutated bridge circuit, through the reactor in parallel with the grid, properly adjusting the amplitude and phase of the bridge circuit AC voltage, or directly control the AC side current, rapid absorption or a reactive power demand, realize dynamic reactive power the purpose of compensation. When the direct current control is used, the AC side current is directly controlled, which can not only track the impulse current of the impact load, but also track the harmonic current.
3, device structure
The SVG device is composed of a connection reactor, a starting device, a IGBT converter valve group and a control system.
4, technical parameters
4.1, input
Power grid voltage: single phase / three, 6kV/10kV/35kV/27.5kV/55kV 50Hz
Allowable operating voltage: < 120%
4.2, compensation performance
Power factor: > 0.95 (in the range of compensation capacity)
Harmonic: meet the power quality of the power quality of the grid harmonic standard GB/T14549-93
System response: up to 5ms
Reliability and life: design life of 20 years, the average failure interval MTBF > 75000 hours, the average recovery time MTTR < 5 minutes
4.3, other
Protection function: over current, short circuit, earthing, over voltage, under voltage, input phase, over temperature, control power supply fault, communication fault
System structure: integrated design, modular design, the overall transport, that is, the use of
High voltage isolation: fiber optic signal transmission
Power semiconductors: IGBT
Cooling: air / water cooling
Protection level: IP20 (special requirements need to be customized)
4.4, control
Control mode: instantaneous current detection technology, PWM current tracking control technology, direct current closed-loop control technology, DC side voltage balance control technology
Control chip: the use of the most advanced digital signal processor DSP, field programmable gate array FPGA
Auxiliary functions: full digital microcomputer control, real time communication network, self diagnosis function, dual power supply
Control function: reactive power compensation, harmonic current compensation, negative sequence current compensation, integrated control
Control power supply: 380VAC or 220VDC
Communication: Modbus protocol
Industrial control machine shows: grid current, power grid voltage, load current, compensation current, active power, reactive power, power factor, etc.
4.5, environment
Use place: indoor, non explosive or corrosive gas
Ambient temperature: 0-40
Ambient humidity: less than 90%, no condensation
Altitude: 1000 meters below (1000 meters above the need to customize)
Storage and transportation temperature：-40℃-70℃
5, technical advantages
SVG belongs to the third generation of dynamic reactive power compensation technology. Based on the voltage source inverter, the reactive power compensation is realized. It is no longer the use of large capacity capacitors, inductors, but through the high frequency switching power electronic devices to achieve reactive power conversion.
As the vast majority of users want to compensate reactive power rather than suction and reactive power, and SVG has a continuous and rapid absorption of reactive power. Therefore, under normal circumstances, the general SVG and FC with the use of such a combination of equipment can not only play the advantages of SVG, but also greatly save the cost of equipment.
