SVG

Static VAR Generator

STATIC VAR GENERATOR (SVG)

POWER FACTOR CORRECTION SYSTEM – Power-factor correction technology is common in the industry as a measure to utilize as much as possible of system capacity and reduce costs due to reactive power consumption. Conventional technology uses a controller that monitors the reactive power consumption and switches capacitor banks to maintain a target power factor.

There are multiple problems with this capacitor-based technology. The most significant issue is the slow response, which leads to over and under-compensation compared to the actual reactive power consumed by the load. The harmonic rich environment present in today’s industry often causes overload on the capacitors due to the change in reactance harmonic frequencies cause. System resonance is also a risk and can lead to a sever overload situation. Overloaded capacitors will have higher leak current and is also a potential fire hazard.

EMES SVG is an entirely new approach to power factor correction. The high-speed, three-level inverter used in the SVG will react to changes in the reactive power, counteracting it by supplying corrective reactive power. The fast response gives a precise and stable real-time power factor correction within ¾ of a cycle, without the problems caused by conventional capacitor-based technology. Both leading and lagging power factor will be continually adjusted. The risk of system resonance is a thing of the past, and the SVG will give full compensation even under low voltage conditions. The EMES SVG is 100% inverter-based, so there are no AC capacitors to fail.

 

SVG OPERATING PRINCIPAL

External current transducers will detect the load current and transmit the signal to the DSP and CPU were a sophisticated reactive power algorithm will extract the reactive power from the apparent power. The reactive power data obtained is used to generate a compensating reactive power signal relayed to the IGBT control, were a PWM signal is created with a switching frequency in the kHz range. Altering the DC bus voltage in comparison with the AC line voltage generates the compensating capacitive or inductive reactive power contribution, which leads to a reactive power exchange with the network.

 

HIGH PERFORMANCE

SVG gives real-time response ensuring continuous adjustment according to plant power factor. High system reliability with transient-free and immediate reaction.

  • Reactive power compensation: Cos Φ = 1.00
  • Constant correction with step-less control. EMES SVG controls from zero to the rated kVAR. In more familiar terms, it can be seen as a power factor compensating VFD.
  • The IGBT control removed the problem with over and under-compensation.
  • Individual correction on each phase
  • Both inductive and capacitive correction from 1 to -1. Previously not possible with conventional technology.
  • Response time of 50μs at full correction in less than 15ms (3/4 of a cycle in a 60Hz system). Ideal for the most challenging systems containing rapid switching reactive loads, e.g., welding factories, cranes.
  • Optimized sizing (size based on the compensation capacity required).
  • Practical and straightforward wall mounting solution for sizes between 50 and 100kVAr.
  • Rack-mounted solutions for 30/50/100kVAr sizes. Multiple combinations of these with up to 500kVAr capacity in one cabinet.
  • Module-based system which simplifies upgrades with increased reactive loads. Combine the sizes needed to meet your plant’s reactive power consumption.

USER-FRIENDLY CONTROL & MONITORING

User-friendly interface on each module, providing the operator with system data like grid voltage, grid current, grid PF, load current, load pf, compensating current, alarm history, and operational status.

  • 7-inch touch screen comes with the cabinet systems ensuring the operator full system overview. Standard unit information is available plus individual module temperatures, total harmonic distortion (both current and voltage), voltage waveforms.
  • Optional alarm monitoring control card for integration into any plant SCADA system
  • RS485, CAN, RJ45 network connections
  • Modbus RTU, Modbus TCP/IP, PMBus network protocols supported

 

GREAT STABILITY AND NETWORK FLEXIBLE

The SVG does not have any adverse effects on the electrical system like conventional capacitor technology. System harmonics cause damage to capacitors and adds a risk of system resonance.

  • Not affected by harmonic distortion and free from harmonic resonance.
  • Will compensate for unbalanced phase loads
  • The SVG is not affected by sudden drop in network voltage and can still deliver full capacity. Operating voltage range is between -40% to 20%.
  • Transient voltage spikes due to switching capacitors are no longer a problem
  • No more overheating of capacitors and harmonic reactors
  • Less than 3% THDi input harmonics will not pollute the network

LONG LIFE EXPECTANCY, DESIGNED FOR THOUGH CONDITIONS  

  • latest generation IGBTs.
  • Innovative three-level inverter topology with high efficiency >97%
  • 3 level inverter topology provides a more accurate waveform with less harmonic content than traditional two-level IGBT technology.
  • No contaminated air used to cool the SVG provides an optimal environment for electronics.
  • Cooling fans with a long lifetime. Modular design and simple to replace.
  • Reduced maintenance cost. No need for time-consuming and costly capacitor bank maintenance and repair.
  • Increased safety. No need to worry about capacitors catching on fire due to swelling or leaking
  • No more contactors to replace
  • Designed for 100,000 hours service intervals
  • Reduced maintenance. Designed for service intervals of more than 100,000hrs equal to more than ten years of 24/7 operation. Systems relying on capacitors can operate for as little as three years before capacitor replacement is needed.
  • High power density resulting in a space-effective solution.

The graph above illustrates how a conventional variable capacitor bank over and under-compensate when trying to adjust to the actual reactive power consumption.

The above illustration shows how the SVG technology works during No reactive load mode, Capacitive mode, and inductive mode.