Reactive power compensation apparatus

Claim 2

A reactive power compensation apparatus - (100) for compensating for reactive power generated by a load (10) connected to a multiphase AC power supply system (I), comprising: (a) means (406) for generating a unit sinusoidal wave signal eld * synchronized with a first phase of an N-phase (N > 2) AC power supply system, and generating a 90° phase-lagged unit sinusoidal wave signal elq * ; (b) means (402, 403) for detecting N-phase load currents ilL, i2L,..., iNL flowing through said load (10), and performing dual phase conversion such that a d-axis of the dual phase conversion, which is associated with d-and q-axes matches a voltage of the first phase of said N-phase AC power supply system to generate dual phase current signals ildL and ilqL; (c) means (408, 410) for performing the following arithmetic operations, using said signals eld*, elq * , ildL, and ilqL: QIP = eld * eilqL -elq*•ildL PIN = eld*•ildL -elq*•ilqL QIN = eld*•ilqL + elq * eildL and obtaining signals QIP, PIN, and QIN; (d) means (413) for producing a signal QIPD representing a DC component of said signal QIP; (e) means (414, 415) for producing signals PIND and QIND by detecting DC components of said signals PIN and QIN; and (f) current command generating means - (420A), responsive to said signals QIPD, PIND, and QIND, for performing arithmetic operations on said signals QIPD, PIND and QIND to generate first-to Nth-phase current commands (IU * -IW*) of the N-phase AC, said reactive power compensation apparatus being controlled on the basis of said current commands (IU * -IW*) generated by said current command generating means.

Claim 3

An apparatus according to claim 2, characterized in that said current command generating means (420A) includes: means (437) for providing a reactive current setting signal QIMAX which designates a maximum value of reactive power to be compensated by said reactive power compensation apparatus; means (421A, 424A) for receiving said signals PIND and QIND, and performing arithmetic operations below: P2ND = PIND•cos(2π/3) -QIND•sin(2π/3) Q2ND = PIND•sin(2π/3) + QIND•cos(2π/3) P3ND = PIND•cos(2π/3) + QIND•sin(2π/3) Q3ND = -PIND•sin(2π/3) + QIND•cos(2π/3) and obtaining signals P2ND, Q2ND, P3ND, and Q3ND; and

Claim 4

means (430A) for receiving said signals QIMAX, QIPD, QIND, Q2ND, Q3ND, PIND, P2ND, and P3ND, and performing arithmetic operations below: IU * = -QIMAX + QIPD -QIND -(P3ND -P2ND)/√3 IV* = -QIMAX + QIPD -Q2ND -(PIND -P3ND)/√3 IW* = -QIMAX + QIPD -Q3ND -(P2ND -PIND)/√3 and generating three-phase current command signals IU*, IV*, and IW*.

Claim 5

An apparatus' according to claim 2, characterized in that said current command generating means (420A) includes: means (437) for providing a reactive current setting signal QIMAX which designates a maximum value of reactive power to be compensated by said reactive power compensation apparatus; means (421B, 424B) for receiving said signals PIND and QIND, and performing arithmetic operations below: Q2ND = PIND•sin(2π/3) + QIND•cos(2π/3) Q3ND = -PIND•sin(2π/3) + QIND•cos(2π/3) and generating signals Q2ND and Q3ND; and means (430B) for receiving said signals QIMAX, QIPD, QIND, Q2ND, and Q3ND, and performing arithmetic operations below: IU * = -QIMAX + QIPD -2QIND IV" = -QIMAX + QIPD -2Q2ND IW* = -QIMAX + QIPD -2Q3ND and generating three-phase current command signals IU*, IV*, and IW*.

Claim 6

An apparatus according to claim 2, characterized in that said current command generating means (420A) includes: means (437) for providing a reactive current setting signal QIMAX which designates a maximum value of reactive power to be compensated by said reactive power compensation apparatus; means (421C, 424C) for receiving said signals PIND and QIND, and performing arithmetic operations below: P2ND = PIND•cos(2π/3) -GIND•sin(2π/3) P3ND = PIND•cos(2π/3) + QIND•sin(2π/3) and generating signals P2ND and P3ND; and means (430C) for receiving said signals QIMAX, QIPD, PIND, P2ND, and P3ND, and performing arithmetic operations below: IU * = -QIMAX + QIPD -2(P3ND -P2ND)/√3 IV* = -QIMAX + QIPD -2(PIND -P3ND)/√3 IW* = -QIMAX + QIPD -2(P2ND -PIND)/√3 and generating three-phase current command signals IU * , IV*, and IW*.

Claim 7

A reactive power compensation apparatus - (100) for compensating for reactive power generated by a load (10) connected to a multiphase AC power supply source (I), comprising: (a) means (406A) for generating a unit sinusoidal wave signal eldl * which is synchronized with a first phase of an N-phase (N > 2) AC power supply source and is associated with a variable phase angle signal θldl*, and generating a 90° phase-advanced unit sinusoidal wave signal elql* with respect to said unit sinusoidal wave signal eldl * ; (b) means (402, 403) for detecting N-phase load currents ilL, i2L,..., iNL flowing through said load (10), and performing dual phase conversion such that a d-axis of the dual phase conversion, which is associated with d-and q-axes, matches a voltage of the first phase to generate dual phase current signals ildL and ilqL; (c) means (404), responsive to said signals eldr, elqr, ildL, and ilqL, for performing arithmetic operations below: PIN = eldl*•ildL + elql*•ilqL QIN = eldr*•ilqL -elql*•ildL and generating signals PIN and QIN; (d) means (409) for producing signals PINA and QINA respectively representing AC components of said signals PIN and QIN, and producing signals PIND and QIND respectively representing DC components of said signals PIN and QIN; (e) means (407), responsive to said variable phase angle signal θIdl*, for generating a unit sinusoidal wave signal eld2 * whose phase angle varies with 2θld*, and generating a 90° phase-lagged unit sinusoidal wave signal elq2 * with respect to said unit sinusoidal wave signal eld2"; (f) means (408A), responsive to said signals eld2*, θlq2*, PINA, and QINA, for performing an arithmetic operation below: QIPD = eId2*•QlNA -eIq2*•PlNA and generating a signal QIPD; and (g) current command generating means - (420A), responsive to said signals QIPD, PIND, and QIND, for performing arithmetic operations on said signals QIPD, PIND and QIND to generate first-to Nth-phase current commands (IU * -IW*) of the N-phase AC, said reactive power compensation apparatus being controlled on the basis of said current commands (IU * -IW*) from said 'current command generating means.

Claim 8

An apparatus according to claim 6, characterized in that said current command generating means (420A) includes: means (437) for providing a reactive current setting signal QIMAX which designates a maximum value of reactive power to be compensated by said reactive power compensation apparatus; means (421A, 424A) for receiving said signals PIND and QIND, and performing arithmetic operations below: P2ND = PIND•cos(2π/3) - QIND•sin(2π/3) Q2ND = PIND•sin(2π/3) + QIND•cos(2π/3) P3ND = PIND•cos(2π/3) + QIND•sin(2π/3) Q3ND = -PIND•sin(2π/3) + OIND•cos(2π/3) and obtaining signals P2ND, Q2ND, P3ND, and Q3ND; and means (430A) for receiving said signals QIMAX, QIPD, QIND, Q2ND, Q3ND, PIND, P2ND, and P3ND, and performing arithmetic operations below: IU * = -QIMAX + QIPD -QIND -(P3ND -P2ND)/√3 IV* = -QIMAX + QIPD -Q2ND -(PIND -P3ND)/√3 IW = -QIMAX + QIPD -Q3ND -(P2ND -PIND)/√3 and generating three-phase current command signals IU * , IV", and IW*.

Claim 9

An apparatus according to claim 6, characterized in that said current command generating means (420A) includes: means (437) for providing a reactive current setting signal QIMAX which designates a maximum value of reactive power to be compensated by said reactive power compensation apparatus; means (421B, 424B) for receiving said signals PIND and QIND, and performing arithmetic operations below: Q2ND = PIND•sin(2π/3) + QIND•cos(2π/3) Q3ND = -PIND•sin(2π/3) + QIND•cos(2π/3) and generating signals Q2ND and Q3ND; and means (430B) for receiving said signals QIMAX, QIPD, QIND, Q2ND, and Q3ND, and performing arithmetic operations below: IU * = -QIMAX + QIPD -2QIND IV* = -QIMAX + QIPD -2Q2ND IW* = -QIMAX + QIPD -2Q3ND and generating three-phase current command signals IU * , IV", and IW*.

Claim 10

An apparatus according to claim 6, characterized in that said current command generating means (420A) includes: means (437) for providing a reactive current setting signal QIMAX which designates a maximum value of reactive power to be compensated by said reactive power compensation apparatus; means (421C, 424C) for receiving said signals PIND and QIND, and performing arithmetic operations . below: P2ND = PIND•cos(2π/3) -QIND•sin(2π/3) P3ND = PIND•cos(2π/3) + QIND•sin(2π/3) and generating signals P2ND and P3ND; and means (430C) for receiving said signals QIMAX, QIPD, PIND, P2ND, and P3ND, and performing arithmetic operations below: IU * = -QIMAX + QIPD -2(P3ND -P2ND)/√3 IV* = -QIMAX + QIPD -2(PIND -P3ND)/√3 IW = -QIMAX + QIPD -2(P2ND -PIND)/√3 and generating three-phase current command signals IU * , IV*, and IW*.