866 words - 4 pages

For emolument of current harmonics (if any), the instantaneous resoluteness of different active and reactive powers is utilized - the active and reactive powers are computed utilizing p-q theory. No restrictions are imposed on the voltage or current wave forms, and it can be applied to three-phase systems with or without a neutral wire for three-phase generic voltage and current wave forms. Thus, it is valid not only in steady state, but withal in transient states.

The p-q Theory first transforms voltages and currents from the a-b-c to α-β-o coordinates, and then defines instantaneous power on these coordinates. Hence, this theory always considers the three-phase system as a unit, not a ...view middle of the document...

28) & (4.29),P ̅_L, and q ̅_L, represent the DC components, which are responsible for fundamental load active and reactive powers. P ̃_L, and q ̃_L represent the AC components which are responsible for harmonic powers.

For load current harmonic compensation, the solar farm inverter should supply the harmonic part of the load current. That is, the reference current signal generation should be based on terms P ̃_L, and q ̃_L. Furthermore, P ̃_L and q ̃_L. can be respectively split into two parts (2ω components and harmonic components) as:

P ̃_L= P_L2ω+P_Lh

q ̃_L= q_L2ω+q_Lh

Where P_L2ωand q_L2ωare the negative active and reactive power (2ω components) originated from asymmetrical fundamental (negative sequence) component of the load current, and P_Lhand q_Lh are the harmonic active and reactive power (harmonic components) of the load current. P ̅_L , q ̅_L and P ̃_L , q ̃_L or P_L2ω, q_L2ωand P_Lh , q_Lh can be extracted by means of low-pass or band-pass Butterworth analog filters. The commands of three-phase compensating currents injected byPV-STATCOM in the α-β coordinates, ico *, icα *, icβ* can be calculated by the following equation:

[█(i_α^*@i_β^* )]=[■(V_α&V_β@V_β&-V_α )][█(-P^*@-q^* )]

Where P^* and q^*are the power components of active and reactive powers to be compensated by the PV-STATCOM. And the reason for including minus signals in the...

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