Power factor correction (PFC) is vital in electrical systems because it ensures that power drawn from the grid is used efficiently. Power factor is defined as the ratio of real (working) power to apparent (total) power.  

A low power factor means much of the supplied energy is “wasted” as reactive power (which does no useful work). Utilities often charge industrial customers based on apparent power (kVA), so poor power factor leads to higher bills and wasted capacity.  

Improving power factor reduces wasted current, lowers heating and losses, and can cut energy costs by 10–30%.  

In practice, PFC equipment is used to minimize reactive demand and raise the power factor toward unity, boosting overall energy efficiency in an installation. 

Traditional PFC methods typically rely on capacitor banks. Basic PFC equipment consists of fixed or switched capacitors (often in “steps”) connected across the supply.  

When loads draw inductive reactive power (like motors or transformers), capacitors inject leading reactive power to cancel it out. Earlier systems used automatic power factor correction (APFC) panels with relay-switched capacitors, or thyristor-switched capacitor (TSC) banks, to switch capacitor stages in and out.  

These solutions are simple and rugged and can raise PF from 0.6–0.85 up to acceptable levels. As one industry source notes, “traditional PFC systems [are] primarily using capacitor banks,” which have been the go-to solution for decades.  

They are often offered alongside older static VAR compensators (SVCs) and synchronous condensers in utility and industrial settings. 

Limitations of traditional capacitor banks: These stepwise systems have several drawbacks. First, switching capacitors is relatively slow and step-based. A new capacitor stage may take a second or more to engage, so correction cannot follow rapidly changing loads. This can lead to over- or under-compensation during transitions (inefficient kVA usage).  

Second, fixed capacitors do not filter harmonics; in fact, if not properly detuned, they can amplify existing harmonic currents. Third, the mechanical components (contactors, relays) need maintenance and can fail over time.  

Third, traditional PFC systems cannot handle leading power factor (PF). This means they are ineffective when the load itself generates leading reactive power, such as from certain types of capacitive equipment or lightly loaded transmission lines. 

Finally, at higher power levels, large capacitor banks become bulky and heavy, and are limited in how close to unity PF they can achieve. In short, traditional PFC is reliable and low-cost, but cannot provide continuous, perfectly matched reactive power under all conditions. 

Modern Active PFC with Static VAR Generators 

To overcome these issues, modern active PFC devices – often called Static VAR Generators (SVGs) – are increasingly used.  

SVGs are power-electronic systems that use insulated-gate bipolar transistors (IGBTs) or similar switches to synthesize precisely the needed reactive current.  

They continuously measure the load current and inject an equal and opposite reactive component in real time. Industry experts point out that SVGs “represent a cutting-edge solution that outperforms traditional PFC systems”. 

Key advantages of SVG-based PFC 

• Instantaneous response: Unlike capacitor banks that switch in steps, an SVG responds in milliseconds. It can correct power factor almost instantly whenever load changes, preventing voltage fluctuations. 

• Continuous, precise control: SVGs adjust in a smooth, analog fashion rather than discrete steps. This means they avoid overshoot or oscillation around the target PF, maintaining near-unity PF under varying loads. 

• Harmonic mitigation: Active converters inherently block low-order harmonics. An SVG can double as an active filter to reduce distortion and flicker. This improves overall power quality beyond mere PF correction. 

• Compact and low maintenance: As a solid-state device, an SVG is much smaller than an equivalent capacitor bank for the same capacity and has no moving parts. This saves space and reduces maintenance costs. 

Because of these benefits, SVG systems are especially suited to modern industrial loads that change rapidly or include sensitive electronics.  

By injecting reactive power at high frequency, they achieve near unity PF even during short transient events. For example, one analysis notes that SVGs use “power electronics to provide real-time reactive power compensation” and can correct PF issues “in milliseconds”, whereas capacitor switching may lag behind. In many facilities, SVGs are replacing or supplementing older APC units to ensure stable voltage and efficiency. 

Hybrid PFC Systems 

A hybrid PFC system combines both approaches – capacitor banks and active SVGs – in one integrated solution. The idea is to get the best of both worlds: the bulk correction of capacitors and the fine-tuning of active electronics.  

As one expert summary explains, hybrid PFC “combine[s] the advantages of both capacitor-based systems and Active Static Var Generators (SVG) to deliver optimal power factor correction”. In practice, this means a switched capacitor bank handles the course (large) reactive load, while an SVG quickly compensates for the remainder. 

The system composition is typically described as: 

• Capacitor bank (discrete subsystem): Covers the majority of reactive power needs in large steps. 

• Static VAR Generator (continuous subsystem): Fills in small leading or lagging power deviations in real time. 

In a hybrid design, the SVG can also take on additional roles during light compensation needs. For example, unused capacity of the power electronics can filter harmonics, balance phases or correct neutral currents when the main reactive load is covered by caps. This makes hybrid PFC especially versatile. One source highlights that hybrid solutions “provide the performance of active with the cost effectiveness of passive”. By offloading most of the reactive power to simple capacitors, the SVG hardware can be smaller (saving cost and energy losses) while still achieving fast and full correction. 

Benefits of hybrid PFC: Because hybrid systems blend the two technologies, they address many shortcomings of each alone. They supply continuous compensation and unity PF (thanks to the SVG), and they handle very large kVAR levels at relatively low cost (thanks to the capacitors). This comprehensive correction “tackles both large and small reactive power demands” to keep PF optimal at all times. In practice this means less wasted capacity and often no PF penalties from utilities. At the same time, the active portion of the hybrid can actively filter harmonics, significantly improving power quality. Facilities see secondary benefits too: better voltage profile, reduced stress on transformers, and higher reliability during fluctuating loads. 

Applications and Considerations 

Facility managers, electrical engineers and sustainability consultants should consider hybrid PFC where loads are heavy, varying or sensitive. Hybrid systems are ideal for large industrial plants (with motors, furnaces, welding, etc.), where both power factor and harmonics matter. They also suit big commercial sites (office buildings, malls, hospitals) that must meet tight utility power quality standards. Renewable energy projects are another application: for instance, solar inverters and wind turbines can introduce harmonic distortion, so a hybrid compensator helps stabilize the local grid. In any setting with mixed or rapidly changing loads, hybrids often pay back faster because they eliminate PF penalties and improve overall system efficiency (sometimes noted as tens of percent savings on bills). 

In contrast, purely passive PFC might still be chosen in very simple, fixed-load cases (like a factory with only motors of known size) because of its low capital cost and simplicity. But even then, an SVG or hybrid solution can extend power plant or generator life by keeping voltage steady and reducing losses. Ultimately, the choice depends on factors like load profile, budget, space, and how tight the PF or harmonic requirements are.  

Conclusion 

In summary, traditional PFC using capacitor banks remains a proven and simple method to correct lagging power factor, but it has limits in speed, flexibility and harmonic control. Hybrid systems, combining those capacitor banks with an SVG, offer a new middle ground: continuous, stepless correction with high capacity at lower overall cost. By “making full use of [each] respective advantage”, hybrid PFC achieves higher power quality and efficiency than either approach alone. For industries and facilities aiming to maximize energy efficiency and meet stringent power quality goals, hybrid PFC represents the state-of-the-art approach.