Dynamic reactive power compensation device SVG (also referred to as the STATCOM) is based on the dynamic reactive power compensation device of high-power inverter, it with high power three-phase voltage type inverter as the core, the output voltage by connecting reactance access system, and the system voltage to keep the same frequency, phase, by adjusting the output voltage amplitude and the relationship between the system voltage amplitude to determine the nature of the output power, when the amplitude is greater than the system when the output voltage amplitude capacitive reactive power, is less than the perceptual reactive power output.

SVG is used for the grid can improve power system stability, increase the system damping, restrain oscillation, which significantly improve voltage transmission ability. With the rapid development of the interregional power grid construction in our country, the problem of dynamic voltage stability of power system reactive power and growing, furnish high voltage large capacity SVG is effective means.

SVG used in power distribution network (also called DSTATCOM), can be effective for wave load of dynamic reactive power compensation, the voltage fluctuation and flicker, the unbalanced load, power factor and harmonic compensation, in effectively improve the power quality at the same time, can obtain obvious energy saving benefit, for example, when the SVG used in rectifier, inverter and other load compensation, often can reduce power consumption by an average of 4% - 4%, economic benefit is very significant.

1、SVG reactive power compensation device and the current domestic advantages compared to other products
　　1）Compensation: domestic capacitor reactive power compensation device is basically be used for reactive power compensation, the power factor of compensation after generally at about 0.8 to 0.9. SVG USES a power supply module for reactive power compensation, the power factor of compensation after generally above 0.98, this is currently the most advanced electric power technology.

2）Levels have no: domestic reactive power compensation device is basically 3-10 level of compensation level, each level is a few thousand law, increase or decrease cannot achieve precise compensation. SVG can compensate the stepless since 0100, fully realize the precise compensation.

3）Harmonic purification: because of reactive power compensation equipment USES a capacitor, capacitance itself can enlarge the harmonics, harmonic, so can't purify SVG can purify more than 50% of the low harmonics.
       4）Service life: domestic reactive power compensation device generally adopts contactor or thyristor control, cause the short service life, generally in three years or so, its loss and regular maintenance. SVG service life in more than a decade, its loss minimum and basically does not need to maintain.

5）Can provide from the perceptual to the capacitive continuous, smooth, dynamic and fast reactive power compensation.

6）Based on IGBT inverter for the controlled current source model compensating device, harmonic resonance and amplification is not going to happen, is not sensitive to system parameters, the security and stability; Traditional SVC is sensitive to system parameters, prone to harmonic voltage amplification and even the phenomenon of resonance.

7）Not only does not produce harmonics, and at the same time have harmonic purification function, at the same time of dynamic reactive power compensation, can undertake purification to harmonic under 13. The SVC TCR in reactive power compensation and produce a large number of harmonic, cause the TCR must be used in conjunction with large-capacity harmonic purification apparatus.

8）SVC response time is about 40-60 ms, and SVG are rarely more than 10 ms response time. When used in distribution network, flicker suppression effect is better than SVC 2-3 times; When used in the grid, and improve the system stability is far superior to the effect of SVC. Reactive compensation needs to be done in instantaneous, if the time is too long can cause it to compensate reactive power when no, dont want to reactive to instead the adverse conditions.

9）SVG as a current source characteristics, output reactive current is not affected by the bus voltage, current source characteristic makes SVG has stronger short-term overload capacity, can be used to further improve power system stability. Type and SVC is impedance characteristics, output reactive current linear decreased with busbar voltage reduction, don't overload capacity.

10）Use H bridge series chain structure, direct access to the 6 kv, 10 kv, 35 kv system, cost reduction. And with N + 1 redundancy Yu Jiegou, a link unit damage can still run at full capacity, higher reliability device itself.

11）Cover an area of an area small, with traditional SVC capacity is 1/3 to 1/2, mobility and good extensibility.

12）SVG can provide active power within a certain range, reduce the active power impact; SVC can provide reactive power.

13）Capacitance and inductance and components used in SVG with SVC completely different technology and production technology, electromagnetic noise significantly reduced during the operation.

14）SVG run losses from 2 to 3 times smaller than with the capacity of SVC, operation cost is low.