Users should know the difference between SVG reactive power compensation and SVC reactive power compensation.

SVG is one of the world’s most advanced reactive power compensation devices at present. It has a response time of ≤5 ms, output harmonic content less than 3%, and overall power loss below 0.8% of its rated capacity. Particularly with the emergence of IGBT devices and advances in control technology, a new type of reactive power compensation equipment—different from traditional ones built on capacitors and reactors—has come into being, namely the SVG (Static Var Generator), also known as Static Synchronous Compensator. Adopting PWM (Pulse Width Modulation) control technology, it can generate capacitive reactive power or absorb inductive reactive power. Since SVG rarely uses a large number of capacitors and instead applies multi‑level technology for bridge converter circuits or PWM technology for operation, there is no need to calculate system impedance during deployment. Compared with SVC, SVG features a smaller footprint, faster continuous, dynamic and smooth regulation of reactive power, as well as bidirectional compensation for both capacitive and inductive reactive power.
 
Key Differences Between SVG and SVC Reactive Power Compensation Devices You Must Know
 
The SVC (Static Var Compensator) was developed thereafter. A typical SVC system consists of TCR (Thyristor Controlled Reactor) plus FC (Fixed Capacitor), i.e., a thyristor‑controlled reactor combined with fixed capacitor banks (usually fitted with series reactors of a certain proportion). A core advantage of the SVC static var compensator is that it can continuously adjust the reactive power of the compensation device by regulating the firing delay angle of thyristors in the TCR. Currently, SVC compensation is mainly applied in medium‑ and high‑voltage power distribution systems, especially suitable for scenarios with large load capacity, severe harmonic issues, impact‑type loads and high load fluctuation rates, such as steel mills, rubber plants, non‑ferrous metallurgy, metal processing, high‑speed railways, etc.
 
Comparative Analysis of SVG and SVC Reactive Power Compensation Devices
 
1. Excellent Low‑Voltage Performance
 
As a current‑source device, SVG’s output capacity is barely affected by busbar voltage. This gives SVG a great edge in voltage regulation: lower system voltage requires more dynamic reactive power regulation. With outstanding low‑voltage characteristics, SVG outputs reactive current independent of system voltage, acting as a controllable constant current source. It can deliver rated reactive current even when system voltage drops, featuring strong overload capacity. In contrast, SVC has impedance‑based characteristics, so its output capacity is highly dependent on busbar voltage. Its reactive current output decreases proportionally with falling system voltage, with no overload capacity available. Therefore, SVG’s reactive power compensation capability is independent of system voltage, while that of SVC declines linearly as system voltage drops.
 
2. Harmonic Characteristics
 
By regulating the equivalent fundamental‑wave impedance of reactors via thyristors, SVC is highly susceptible to system harmonics and generates substantial harmonics itself. Thus, filter banks must be installed to eliminate harmonics produced by SVC. SVG adopts three‑level single‑phase bridge technology, enabling single‑phase output of 5‑level voltage waveforms with carrier phase‑shift pulse modulation. It is less affected by system harmonics and can even suppress them. Compared with SVC, SVG significantly reduces harmonic content in compensation current through multiplexing, multi‑level and pulse‑width modulation technologies.
 
3. Different Working Principles
 
Centered on high‑power voltage‑source inverters, SVG rapidly absorbs or generates required reactive power to achieve fast dynamic regulation by adjusting the amplitude and phase of inverter output voltage, or directly controlling those of AC‑side current.
 
SVC can be regarded as a dynamic reactive power source. Depending on grid connection requirements, it supplies capacitive reactive power to the grid or absorbs excess inductive reactive power from it. Capacitor banks, usually connected to the grid as filter banks, provide reactive power. When the grid has surplus capacitive reactive power, a parallel reactor absorbs it. The reactor current is controlled by thyristor valve banks. By adjusting the thyristor firing angle, the effective value of reactor current is modified, ensuring the reactive power at the SVC grid‑connection point stabilizes the local voltage within specified ranges, thereby realizing grid reactive power compensation.
 
4. Different Response Speeds
 
SVG has a response speed of ≤5 ms, which better mitigates voltage fluctuations and flickers. SVC features a response speed of 20–40 ms. Under the same compensation capacity, SVG achieves superior compensation effects against voltage fluctuations and flickers.
 
5. Smaller Footprint
 
With identical compensation capacity, SVG occupies 1/2 to 2/3 less space than SVC. As SVG uses fewer reactors and capacitors, its overall volume and footprint are greatly reduced. The reactors in SVC are bulky by themselves, and the required installation spacing between components leads to a larger overall footprint.
 
In summary, SVG reactive power compensation devices feature fast response speed, low harmonic content and strong reactive power regulation capability, which greatly improve power quality. They have become the mainstream development direction of reactive power compensation technology.
 
6. Improved Operational Safety
 
SVC mainly relies on thyristor‑regulated reactors and multiple capacitor banks for reactive power compensation, which is prone to resonance amplification leading to safety hazards. Its compensation effect is severely impacted by drastic system voltage fluctuations, accompanied by high operational losses.
 
SVG requires no filter banks for its matching capacitors and has no resonance amplification risks. As an active compensation device composed of turn‑off IGBT power devices, SVG avoids resonance issues, greatly enhancing operational safety.
 
Key Differences Between SVG and SVC Reactive Power Compensation Devices You Must Know
 
Based on the above six aspects — low‑voltage performance, harmonic characteristics, working principles, response speed, footprint and operational safety — the differences between SVG and SVC are clear. This helps users determine when to select SVG compensation cabinets and when to choose SVC ones. In fact, SVC has been largely phased out and gradually replaced by SVG since its market launch. Thanks to its more advanced technology, faster response speed and higher‑precision compensation effects, SVG optimizes power quality effectively. Both 6 kV and 10 kV dynamic SVG compensation cabinets are widely applied in the market.
 
For any inquiries regarding dynamic SVG compensation cabinets, please feel free to contact Shanghai Kunyou Electric Co., Ltd., a professional manufacturer of dynamic SVG compensation cabinets.