Static Var Compensation System Design Basics

Designing a static var compensation system starts with accurate load measurement, then selects technology, protection, and control strategy. This guide focuses on practical evaluation steps for U.S. industrial and commercial buyers—measurement, documentation, and lifecycle support—not generic marketing claims. Where equipment selection is involved, cross-check public specifications on cnbygele.com and confirm project-specific limits with your utility or consulting engineer. Section checklists can be reused as RFQ attachments and commissioning handover outlines.

Part 1. Site Survey and Data

Collect voltage, current, PF, THD, and load duty cycles for at least one representative week.

Reactive power compensation addresses power factor, voltage drop, and transformer loading—not active energy consumption directly.

Utilities may apply demand charges or PF penalties; compensation can reduce billed kVA if aligned with tariff rules.

Automatic reactive power controllers switch capacitor steps based on measured reactive power or power factor.

Capture nameplate data, single-line drawings, and utility interconnection rules in the RFQ package to reduce back-and-forth during technical review.

If your site mixes linear motors and nonlinear electronics, treat harmonic and reactive targets as linked requirements rather than separate purchases.

Define acceptance criteria before shipment—power factor, step response, or THD at agreed load points—so commissioning disputes are less likely.

Part 2. System Architecture

Centralized compensation at the main bus is common; larger sites may use zone compensation near heavy loads.

Sizing should use interval data from power analyzers rather than nameplate assumptions alone.

Over-compensation raises voltage; under-compensation leaves penalties and thermal stress unresolved.

When load varies within seconds, consider SVG product line instead of rapid capacitor switching that wears contactors.

Capture nameplate data, single-line drawings, and utility interconnection rules in the RFQ package to reduce back-and-forth during technical review.

If your site mixes linear motors and nonlinear electronics, treat harmonic and reactive targets as linked requirements rather than separate purchases.

Define acceptance criteria before shipment—power factor, step response, or THD at agreed load points—so commissioning disputes are less likely.

Part 3. Protection and Standards

Coordinate overvoltage, inrush, and harmonic limits with utility interconnection requirements.

Installation must respect clearances, ventilation, and arc-flash labeling per site safety program.

As-built drawings and test records support future audits and insurance reviews.

See CNBYG power quality system options when multiple feeders share compensation goals.

Capture nameplate data, single-line drawings, and utility interconnection rules in the RFQ package to reduce back-and-forth during technical review.

If your site mixes linear motors and nonlinear electronics, treat harmonic and reactive targets as linked requirements rather than separate purchases.

Define acceptance criteria before shipment—power factor, step response, or THD at agreed load points—so commissioning disputes are less likely.

Part 4. Documentation and Handover Checklist

Industrial acceptance should not rely on energization alone—documentation proves ratings, safety, and maintainability for the next maintenance cycle.

Use the tables below as a starting RFQ checklist; your utility or EPC contract may require additional items.

For product-specific datasheets, cross-check related CNBYG product pages and request any missing type test excerpts.

Align factory acceptance tests with items your insurer or utility interconnection agreement may require.

When comparing quotations, normalize currency, Incoterms, and included commissioning services before ranking suppliers.

Part 5. Commissioning, Monitoring, and Long-Term Operations

Commissioning should verify that reactive and harmonic targets are met at the point of common coupling, not only at the compensation cabinet terminals.

Functional tests typically include step response, power factor at defined load points, and harmonic readings compared to contract or IEEE 519 guidance where applicable.

Monitoring after energization helps catch hunting, unexpected resonance, or capacitor cell failures before they affect production uptime.

Train maintenance staff on lockout/tagout, discharge timing for capacitors, and which alarms require immediate shutdown versus scheduled service.

Schedule a post-warranty review to reassess load changes—production line upgrades often change compensation needs within three to five years.

Utility account managers can clarify whether PF adjustments affect demand charges only, energy charges, or both—align KPIs before writing acceptance tests.

Keep a spare-parts criticality list (fuses, contactors, fan assemblies, control boards) based on lead time and production impact, not catalog defaults alone.

Recommended CNBYG Products

For project support, explore our related product line, power quality system options, and OEM/ODM capabilities on cnbygele.com.

FAQ

How do you size a static var compensation system?

Sizing is driven by load flow and dynamic performance studies to determine required leading and lagging reactive power. Public utility criteria (PJM) list PSS/E load flow, dynamic studies, and harmonic impedance studies as common tasks done with the manufacturer.

What studies are needed for SVC design?

Beyond sizing studies, PJM criteria call for insulation coordination, surge and lightning protection design, interference studies (radio, audible noise), and reliability/availability (RAM) requirements. Components must meet ANSI, IEEE, NEMA and related standards.

How is an SVC protected?

Protection references show TCR and TSC branches typically delta-connected with three differential zones, each covering one set of thyristor valves and one reactive element, overlapping at the thyristor CTs. Modern microprocessor relays consolidate these functions.

What data should a site survey collect first?

Collect voltage, current, power factor, THD, and load duty cycles over a representative period, and include motor start events since they define peak reactive demand. Accurate data improves sizing and avoids over/under compensation.

How fast does an SVC control system respond?

Vendor documentation cites reaction times around 5 ms for arc-furnace-type loads and roughly 25-100 ms for general industrial loads and grid substations, depending on the controlled parameter.

Should an APF be integrated into the same panel?

When THD is high, a combined study with an active power filter may be required. Coordinating reactive compensation and harmonic mitigation avoids resonance and treats power quality as one system.

Centralized or distributed compensation?

Centralized compensation at the main bus is common and simpler to control; distributed compensation near heavy loads provides local support at the cost of more equipment. The choice follows the load map and cable reactive losses.

References

• PJM — SVC Design Criteria (PDF)
• WPRC — Lessons Learned in SVC Protection (PDF)
• UKKZ — SVC control & protection
• IJSREM — Optimal Placement & Sizing of SVC

Ready to discuss your project? Contact CNBYG engineering support with your voltage class, load list, and target power factor or THD goals.