Comparative Analysis of Static Var Generator (SVG) and TSC Reactive Power Compensation Device

When selecting equipment, customers need to move beyond simply comparing individual devices and instead consider the overall optimization of the power system, taking into account key factors such as dynamic response requirements, harmonic environment, long-term operation and maintenance costs, and space constraints. However, in applications with impact loads, SVG (Static Var Generator) installation should be given priority.

I. Core Advantages of SVG Compared to TSC

1. Millisecond-Level Dynamic Response
SVG, based on IGBT power devices, has a response time of <10ms, enabling real-time tracking of load changes (such as electric arc furnaces and rolling mill impact loads).
TSC relies on mechanical switches (contactor/thyristor switching), with a response speed of 10-40 cycles (200ms-800ms), and cannot suppress rapid voltage fluctuations.

2. Stepless Continuous Compensation, No Inrush Current
SVG output current amplitude/phase can be precisely adjusted, achieving continuous and smooth reactive power output.

TSC uses grouped capacitor switching, resulting in a stepped compensation blind zone. Inrush currents of 5-20 times the rated current are generated during switching, threatening equipment lifespan.

3. Output Unaffected by Voltage
SVG can still output rated capacitive/inductive current (such as STATCOM topology) even at voltages as low as 20%Un.

TSC output reactive power is proportional to the square of the voltage (Q∝U²), and its compensation capability drops sharply at low voltages.

4. Bidirectional Compensation Capability

SVG can simultaneously provide capacitive reactive power (+Q) and inductive reactive power (-Q), perfectly solving the overcompensation problem under light loads.

TSC typically only outputs capacitive reactive power, requiring additional reactors to compensate for inductive reactive power, increasing system complexity.

5. Suppression of Voltage Flicker and Harmonics

SVG can incorporate active power filter (AHF) functionality, suppressing characteristic harmonics such as the 5th, 7th, and 11th orders while compensating for reactive power (e.g., when connected to a frequency converter load).

TSC lacks harmonic mitigation capabilities and may even amplify harmonics (requiring the configuration of detuning reactors).

II. Key Considerations for SVG Selection

1. Capacity Calculation and Overload Capacity

Capacity Selection: Based on the maximum reactive power deficit plus harmonic compensation margin (a 20% margin is recommended). For example, if load fluctuations cause a peak reactive power demand of 4 Mvar, a 5 Mvar SVG should be selected.

Overload Capacity: Focus on 1.1 times long-term overload and 1.5 times short-term (1 min) overload capacity to cope with transient impacts.

2. Grid Environment Adaptability

Voltage Level: Confirm the system voltage (e.g., 6kV/10kV/35kV) and allowable deviation (±10%).

Harmonic Background: If THDv > 3% (e.g., in steel mills, chemical plants), an SVG with harmonic suppression function must be selected, and the harmonic current output capacity must be calculated.

3. Heat Dissipation and Protection Design

Heat Dissipation Methods:

Small Capacity (<2Mvar): Air Cooling (IP41)

Medium and Large Capacity (>2Mvar): Water Cooling (IP54), suitable for dusty workshops

Ambient Temperature: Derating is required above 40℃ (1% derating for every 1℃ increase).

4. Control Strategy and Protection Functions

Core Algorithm: Select models employing instantaneous reactive power theory (p-q or ip-iq method) to ensure compensation accuracy.

Key Protections: Multi-level protection against DC overvoltage, IGBT overcurrent, and radiator overheating; MTBF (Mean Time Between Failures) should be >100,000 hours.

5. Hybrid Application with TSC

Solution Design: Base load is compensated by TSC, while fluctuations are dynamically tracked by SVG (e.g., a “TSC+SVG” hybrid compensation system), reducing overall costs.

Control Coordination: TSC/SVG collaborative control is achieved through a host computer to avoid switching oscillations.