Choosing the appropriate PFC equipment involves a systematic approach, requiring expertise in the following steps:
Step 1: Use of Active & Passive Power Factor Correction Techniques
The first step is to calculate the required (Qc in kvar) based on its reactive power (cos φ) and apparent power (S).
Qc can be calculated using the formula Qc = P (tan φ – tan φ‘), derived from the diagram, where:
- Qc=Capacitor bank power (kVAr).
- P = power in active mode (kW)
- tan φ = tan of pushing angle considering the uncompensated phase shift.
- φ̂ ‛ = tan φ ‛ = tangent of phase shift angle after compensation.
φ and tan φ parameters can be obtained from meeting billing data or from the direct measurements taken at the installation site.
Step 2: Choice of the Compensation System
The interface capacitance can be set based location-wise (entire grid) or by sector (section by section).
Factors influencing location choice include:
- Overall objectives (e.g., avoiding penalties on reactive energy, relieving transformers)
- Operating mode (consistent or varying that shifts)
- Impacts of capacitors predictable on network characteristics.
- Installation costs
Step 3: Decision on Form of Remuneration
Different compensation types are utilized based on performance requirements and control complexity:
- Fixed: Interconnect a variable capacitor bank in the form of a fixed valve.
- Automatic: Link steps to make the system flexible and capable of controlling the energy output.
- Dynamic: Well-suited for balancing lumpy loaders.
Step 4: Converters & FRAs Must Be Designed To Accommodate the Variations in Operating Conditions & Harmonics.
Operating conditions significantly affect capacitor lifespan, necessitating consideration of parameters such as:
- Ambient temperature (°C)
- Induce expected over-current by the impact of voltage disturbances.
- Maximum switching operations annually
- Desired lifespan
Certain loads lead to the prevalence of harmonics in the power network, which is detrimental to capacitors. In this context, the harmonic effects should be assessed because they ensure the optimal performance and life span of capacitors.