Power system control apparatus

Claim 2

An apparatus according to claim 1, characterized by further comprising phase difference angle estimating means (107), coupled to said power system impedance estimating means (105), for estimating a phase difference angle from the power system impedance estimated by said power system impedance estimating means.

Claim 3

An apparatus according to claim 1, characterized by further comprising phase difference angle estimating means (107), coupled to said power system impedance estimating means (105), for estimating a phase difference angle from the power system impedance estimated by said power system impedance estimating means, and gain schedule means for changing a control parameter of said power system stabilizing means (109) based on one of the power system impedance estimated by said power system impedance estimating means (105) and the phase difference angle estimated by said phase difference angle estimating means (107).

Claim 4

A power system control apparatus characterized by comprising: auto voltage regulating means (103) for keeping an output voltage at a constant value during normal operation of a generator; and power system stabilizing means (109) for suppressing a power fluctuation in power system including said generator, said power system stabilizing means (109) comprising correction signal arithmetic means (111) and output means (113, 115), said correction signal arithmetic means (111) receiving parameters including a phase difference angle change, a phase difference angle differential, and a power system impedance, and calculating a correction signal of a target voltage value of said auto voltage regulating means (103) from these parameters, said output means (113, 115) outputting the correction signal obtained by an arithmetic operation to said auto voltage regulating means (103).

Claim 5

An apparatus according to claim 4, characterized in that said correction signal arithmetic means for calculating the correction signal of the target voltage value of said auto voltage regulating means comprises non-linear arithmetic means (111) for non-linearly calculating the power system impedance, the phase difference angle, and the phase difference angle differential, and said output means comprises a leading-delaying filter (113) for receiving a result calculated by said nonlinear arithmetic means, and a reset circuit (115) receiving a signal output from said leading-delaying filter and resetting the correction signal of the target voltage value.

Claim 6

An apparatus according to claim 4, characterized by comprising a power system state estimating unit (106) for obtaining estimated values of the power system impedance and the phase difference angle.

Claim 7

An apparatus according to claim 6, characterized in that said power system impedance estimating means (106) includes a table (105) for storing a plurality of system impedances calculated from a plurality of terminal voltages of said generator and a plurality of internal powers of said generator.

Claim 8

A power state estimating unit comprising: input means (131 to 134) for receiving signals representing a terminal voltage, an active power, and a reactive power of a generator; and estimating means (135 to 144), used for estimating a power system impedance and a phase angle used for controlling a system power of a power system including said generator, for non-linearly calculating the signals received from said input means, and outputting signals representing an estimated power system impedance and an estimated phase difference angle.

Claim 9

A power state estimating unit according to claim 8, characterized in that said input means comprises means (134) for receiving a signal representing a rotational number of said generator.

Claim 10

A power state estimating unit according to claim 8, characterized in that said input means comprises filter means (131 to 133) for receiving at least one of the signals representing the terminal voltage, the active power, and the reactive power, and removing a noise component from the received signals.

Claim 11

A power state estimating unit according to claim 10, characterized in that said filter means (131 to 133) comprises a filter including a delaying element.

Claim 12

A power state estimating unit according to claim 8, characterized in that said estimating means comprises a filter (141) for removing a change in phase difference angle contained in an approximated value of the power system impedance by utilizing a difference in response waveform between a signal representing the power system impedance that changes substantially in a stepwise manner, and a signal representing the phase difference angle that changes continuously and vibration-like manner.

Claim 13

A power state estimating unit according to claim 12, characterized in that said filter (141) comprises a delaying filter including a delaying element.

Claim 14

A power state estimating unit according to claim 8, characterized in that said input means has a means (146) for receiving the signal representing the rotational number of said generator, and said estimating means includes means (147, 148) for calculating the signals representing the rotational number and the active power, and outputting an estimated rotational number of said generator.

Claim 15

A power state estimating unit according to claim 8, characterized in that said estimating means comprises means (135 to 138) for calculating d- and q-axes armature currents and an internal voltage of said generator from the terminal voltage, the active power, and the reactive power, means (140, 141) for calculating the power system impedance from the d-and q-axes armature currents and the internal voltage of said generator, and means (142 to 144) for calculating the phase difference angle from the d- and q-axes armature currents, the internal voltage of said generator, and the power system impedance.

Claim 16

A power state estimating unit according to claim 14, characterized in that said estimating means comprises means (146) for filtering a sum of the rotational number and the active power of said generator and outputting a sum signal, and means (148) for integrating or filtering a difference between the sum signal and the active power to obtain the estimated generator rotational number.

Claim 17

A power state estimating unit according to claim 14, characterized by further comprising filtering means (131 yo 133) for filtering at least one of signals representing the terminal voltage, the active power, and the reactive power.

Claim 18

An angular velocity detecting unit comprising: input means, coupled to a turbine generator, for receiving a signal representing a rotational number of said turbine generator, a signal representing a transmission active power, and a phase difference angle signal; and angular velocity calculating means (153, 155) for calculating an angular velocity from the signals received by said input means in accordance with a fluctuation equation of said turbine generator.

Claim 19

An angular velocity detecting unit according to claim 18, characterized in that said angular velocity calculating means (153, 155) calculates the angular velocity from a phase angle deviation signal of said generator corresponding to the phase difference angle signal.

Claim 20

An angular velocity detecting unit according to claim 18, characterized in that said angular velocity calculating means comprises two integrators (154, 155) for respectively calculating an angle and an angular velocity.