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Harmonic Mitigation :question:- Part 4 (G4: Reduction of load sensitivity…

- - - - a) reduction of Harmonics Emission from a Non-Linear Load
        
        to reduce the magnitude of generated harmonics depend on the load type
        
        in the case of an arc furnace it is a comprehensive set of actions aimed at steadying its operation
      - b) Line Reactors in Converter Circuits
        
        The use of a.c. line reactors or d.c. side reactors significantly reduces the level of converter current distortion
      - c) Multi-Pulse Converter Systems
        
        Increasing the number of pulses to reduce the converter current distortion factor and therefore to mitigate the adverse effects of harmonics in a power system
        
        connecting in series, or in parallel, converters with a smaller number of pulses and ensuring an appropriate phase shift between the voltages supplying the bridges
        
        Multi-Puse VFD's - 12 Pulse
        
        Advantages
        
        Cost Varies
        
        Substantial reduction in harmonics
        
        Disadvantages
    - - Passive
        
        Passive (or passive-tuned) filters are relatively inexpensive but they have potential for adverse interactions with the power system.
        
        They are used either to shunt the harmonic currents off the line or to block their flow between parts of the system by tuning the elements to create a resonance at a selected harmonic frequency.
      - Active
- - - - Extension of the supply system
      - Elimination of series reactors
      - parallel operation of Supply lines and transformers;
      - Application of transformers of larger power and/or lower short-circuit voltage, etc.
    - - These may also include compensation of the line impedance by means of series capacitors of fixed or, recently, variable capacitance.
      - •Supplying large non-linear loads directly from an HV line is an advantageous solution.
      - •It guarantees a sufficiently large short-circuit capacity at the point of connection, and a larger voltage distortion can be accepted in such a line since harmonic-sensitive loads are not connected to it.
- - - - K Factor is a number that quantities potential losses in transformer due harmonic currents
        
        Helps in selecting transformer
    - - The second method is used in Europe, and is based on the estimation of how much a standard transformer should be derated so that the total loss on harmonic load does not exceed the fundamental design loss: this is called factor K:
        where:-
        e is the ratio of fundamental frequency eddy current loss to ohmic loss, both at the reference temperature;
        I is the r.m.s. value of the current including all harmonics;
        In is the magnitude of the nth harmonic;
        I1 is the magnitude of the fundamental current;
  - - - Depends on the ambient temperature
      - The laying method