Power Quality Solutions
2021-10-29
●Preview:
■General:
▲The increasing demand of electricalpower and the awareness of the necessity of energy saving is very upto date these days. Also the aware-ness of power quality is increasing,and power factor correction (PFC) andharmonic filtering will be implementedon a growing scale. Enhancing powerquality – improvement of power factor– saves costs and ensures a fast return on investment. In power distrib-ution, in low- and medium-voltagenetworks, PFC focuses on the powerflow (cos φ) and the optimization ofvoltage stability by generating reactivepower – to im prove voltage quality andreliability at distribution level.
■How reactive power is generated:
▲Every electric load that works withmagnetic fields (motors, chokes,transformers, inductive heating, arcwelding, generators) produces a vary-ing degree of electrical lag, which iscalled inductance. This lag of inductiveloads maintains the current sense (e.g.positive) for a time even though thenegative-going voltage tries to reverseit. This phase shift between currentand voltage is maintained, current andvoltage having opposite signs. Duringthis time, negative power or energy is produced and fed back into the network. When current and voltagehave the same sign again, the sameamount of energy is again needed tobuild up the magnetic fields in induc-tive loads. This magnetic reversal energy is called reactive power.
▲In AC networks (50/60 Hz) such aprocess is repeated 50 or 60 times asecond. So an obvious solution is tobriefly store the magnetic reversal energy in capacitors and relieve thenetwork (supply line) of this reactiveenergy. For this reason, automatic reactive power compensation systems(detuned/conventional) are installed forlarger loads like industrial machinery.Such systems consist of a group ofcapacitor units that can be cut in andcut out and which are driven andswitched by a power factor controller.
■General:
▲The increasing demand of electricalpower and the awareness of the necessity of energy saving is very upto date these days. Also the aware-ness of power quality is increasing,and power factor correction (PFC) andharmonic filtering will be implementedon a growing scale. Enhancing powerquality – improvement of power factor– saves costs and ensures a fast return on investment. In power distrib-ution, in low- and medium-voltagenetworks, PFC focuses on the powerflow (cos φ) and the optimization ofvoltage stability by generating reactivepower – to im prove voltage quality andreliability at distribution level.
■How reactive power is generated:
▲Every electric load that works withmagnetic fields (motors, chokes,transformers, inductive heating, arcwelding, generators) produces a vary-ing degree of electrical lag, which iscalled inductance. This lag of inductiveloads maintains the current sense (e.g.positive) for a time even though thenegative-going voltage tries to reverseit. This phase shift between currentand voltage is maintained, current andvoltage having opposite signs. Duringthis time, negative power or energy is produced and fed back into the network. When current and voltagehave the same sign again, the sameamount of energy is again needed tobuild up the magnetic fields in induc-tive loads. This magnetic reversal energy is called reactive power.
▲In AC networks (50/60 Hz) such aprocess is repeated 50 or 60 times asecond. So an obvious solution is tobriefly store the magnetic reversal energy in capacitors and relieve thenetwork (supply line) of this reactiveenergy. For this reason, automatic reactive power compensation systems(detuned/conventional) are installed forlarger loads like industrial machinery.Such systems consist of a group ofcapacitor units that can be cut in andcut out and which are driven andswitched by a power factor controller.
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