RENEWABLE ENERGY SYSTEMS
LV TRANSFORMER AND REACTOR SOLUTIONS
Renewable Power Electronics Applications
In renewable energy systems, inverter outputs create much more challenging operating conditions compared to conventional systems due to high harmonic content (THDi 30–60%), high dv/dt, high di/dt, and rapid load changes.
OMSAN approaches these problems not with a standard product approach, but with application-specific engineering solutions.
PROBLEM: HIGH HARMONICS AND LOSSES
Harmonics originating from the inverter:
• Increases THDi to 30–60%
• Creates eddy current and stray loss in the windings
• Causes local overheating and efficiency reduction
OMSAN SOLUTION
OMSAN optimizes LV/LV transformers and line reactors together to solve this problem.
HOW IT DESIGNS
• Analyzes the harmonic spectrum in detail (not just THDi, but also distribution)
• Sizes the transformer according to effective RMS loading
• Designs to be compatible with K-Factor (K-13 / K-20)
• Determines the leakage reactance (Z%) according to inverter compatibility
• Optimizes the conductor geometry against skin & proximity effect
• Calculates losses depending on harmonic frequencies
HOW IT PRODUCES
• Winds the coils homogeneously and with low losses
• Provides complete insulation and thermal resistance with VPI
• Applies low contact resistance connections
• Controls the partial discharge level <10 pC
RESULTS
• THD: 30–60% → can be reduced to <5%
• Additional losses are significantly reduced
• Temperature rise is controlled
PROBLEM: HIGH dv/dt AND INSULATION STRESS
Fast voltage fluctuations at the inverter output:
• Create stress on the insulation system
• Cause partial discharge and premature failures
OMSAN SOLUTION
OMSAN implements a high dv/dt withstand LV/LV transformer design.
HOW IT DESIGNS
• Selects the insulation system according to the dv/dt level
• Optimizes the winding structure to balance the voltage distribution
• Controls the electric field density
HOW IT PRODUCES
• Provides gapless insulation with VPI
• Applies uniform insulation placement between windings
•Verifies quality with partial discharge tests
RESULT
• Insulation stress is reduced
• Risk of failure is lowered
•Equipment life is significantly extended
PROBLEM: HIGH di/dt AND CURRENT PEAKS
Rapid current changes:
• Damage inverter semiconductors
• Create sudden current peaks
• Create electromagnetic stress in the system
OMSAN SOLUTION
OMSAN controls current dynamics with LV line reactors.
HOW IT IS DESIGNED
• Determines the required inductance based on system analysis
• Optimizes within a 3–5% reactance range
• Adjusts the impedance characteristic according to harmonic frequencies
HOW IT IS MANUFACTURED
• Applies air gaps with precise tolerances
• Creates a balanced magnetic field by ensuring winding symmetry
• Provides resistance to electromagnetic forces with a mechanically robust structure
RESULT
• di/dt is limited
• Current peaks are reduced
•Inverter protection level is increased
PROBLEM: THERMAL STRESS AND OVERHEATING
Harmonics and high RMS current:
• Causes excessive temperature increase in transformers and reactors
• Reduces insulation life
OMSAN SOLUTION
OMSAN designs thermally optimized transformers and reactors.
HOW IT DESIGNS
•Performs hot-spot analysis
• Optimizes current density
• Selects core and conductor to minimize losses
HOW IT PRODUCES
• Designs balanced cooling channels
• Creates a mechanical structure that improves heat dissipation
• Increases thermal conductivity with resin application
RESULT
•Temperature rise is reduced
•Thermal stress is reduced
• Equipment life is extended
PROBLEM: SYSTEM INSTABILITY AND RESONANCE
Incorrect impedance and filter design:
• Can create resonance
• Can destabilize the system
OMSAN SOLUTION
OMSAN designs transformers and reactors together to control system impedance.
HOW IT DESIGNS
• Optimizes leakage reactance (Z%)
• Performs LCL filter and resonance analyses
• Balances system impedance
HOW IT PRODUCES
• Precisely controls inductance tolerances
• Provides stable magnetic structure
RESULT
•Resonance risk is eliminated
• The system operates stably
GENERAL SYSTEM IMPROVEMENT
With OMSAN solutions:
• THD → decreases from 30-60% to <5%
• Current waveform → approaches a sine wave
• Thermal load → significantly reduced
• Risk of failure → minimized
• Equipment life → significantly increased
CONCLUSION
With OMSAN solutions:
• Analyzes the problem
• Designs the product accordingly
• Guarantees quality through controlled production
and makes the system:
• More efficient
• More stable
• Longer lasting
TRANSFORMERS
