Abstract: The disclosure provides a technique for appropriately recovering an output reduction due to PID. A solar power generation system which has a solar cell, converts an output of the solar cell to predetermined AC power and outputs the converted AC power includes a voltage application part configured to apply an DC voltage to the solar cell and to perform an output recovery operation, and a stop control part configured to stop applying of the DC voltage when a stop condition is satisfied after the DC voltage is applied. Further, when an output correspondence information acquisition part that acquires output correspondence information indicating a value corresponding to an output value of the solar cell is provided, stop control part determines that the stop control part satisfies the stop condition and stops the applying of the DC voltage when the output value corresponding to the output correspondence information exceeds a threshold value.

Abstract: A power conditioner that suppresses distortion in a waveform of a sinusoidal generated voltage includes a first and second group including two switches each connected in inverse parallel and in series. The power conditioner alternately turns on and off both switches in the first group at a prescribed chopping frequency and alternately turns on and off both switches in the second group at a PWM frequency higher than the chopping frequency. If control is performed with a dead-time provided in the on/off timing for both switches in each group, the power conditioner adjusts and controls the on/off duty for the second group switches to correspond to the effective on drive in one switch by each diode during the dead-time for each switch in the first group.

Abstract: A power conditioner that suppresses generation of voltage spikes in a part of a generated sinusoidal voltage waveform. An offset between the timing of chopping, which depends on whether the voltage difference between the voltage of a third pulse voltage series and a sinusoidal voltage is positive or negative, and the timing of the switching between on/off duty cycles of a seventh and eighth switch is calculated, and the on/off duty cycles of the seventh and eighth switches are controlled on the basis of the timing offset.

Abstract: An isolated operation detecting method according to the present invention includes: a first step that injects a power fluctuation into the power system; a second step that measures a system cycle; a third step that adjusts the injection of the power fluctuation so that the system cycle increases when the system cycle is found increased than the previous system cycle as a result of the measuring, and decreases when the system cycle is found decreased than the previous system cycle; a fourth step that produces a change pattern of a latest system cycle on the basis of a deviation of the latest system cycle from a fixed number of cycle-passed previous system cycle; and a fifth step that determines an isolated operation on the basis of the change pattern.

Abstract: An isolated operation detecting method according to the present invention includes: a first step that injects a power fluctuation into the power system; a second step that measures a system cycle; a third step that adjusts the injection of the power fluctuation so that the system cycle increases when the system cycle is found increased than the previous system cycle as a result of the measuring, and decreases when the system cycle is found decreased than the previous system cycle; a fourth step that produces a change pattern of a latest system cycle on the basis of a deviation of the latest system cycle from a fixed number of cycle-passed previous system cycle; and a fifth step that determines an isolated operation on the basis of the change pattern.

Abstract: An apparatus for controlling the operation of power conditioners (10) for supplying the generated power to an external power system such as a commercial power system, in which power conditioners (10) are interconnected to an external power system, the power conditioners (10) are interconnected through information exchange means, at least one of the power conditioners (10) monitors the reverse power flow, and the power conditioners (10) exchange the monitor information with information of the other power conditioners (10), thereby equalizing the outputs of all the power conditioners (10). A generator (42) has armature windings (60), and an inverter circuit (13) of the power conditioner (10) provided for each of the armature windings (60) is controlled by cable or radio.

Abstract: A direct current detection circuit has a zero-phase current transformer with source lines inserted therethrough for detecting current differences among them and generates a comparison voltage value based on a divided voltage value obtained between the zero-phase current transformer and a voltage divider resistor according to a change in the self-impedance of the zero-phase current transformer. An offset current is passed through the zero-phase current transformer to make it possible to detect on the basis of the comparison voltage value a direct current value in a range which is otherwise difficult to detect accurately on the basis of the comparison voltage value because of influence of hysteresis characteristic of the zero-phase current transformer. A control circuit detects a present direct current value based on the comparison voltage value and the value of the offset current.

Abstract: A direct current detection circuit has a zero-phase current transformer with source lines inserted therethrough for detecting current differences among them and generates a comparison voltage value based on a divided voltage value obtained between the zero-phase current transformer and a voltage divider resistor according to a change in the self-impedance of the zero-phase current transformer. An offset current is passed through the zero-phase current transformer to make it possible to detect on the basis of the comparison voltage value a direct current value in a range which is otherwise difficult to detect accurately on the basis of the comparison voltage value because of influence of hysteresis characteristic of the zero-phase current transformer. A control circuit detects a present direct current value based on the comparison voltage value and the value of the offset current.

Abstract: An electric power conversion device comprises switching elements 2a, 2b making up a push-pull converter, a pulse transformer T, a rectification diode D1, a rectification diode D2, a choke coil L, a smoothing capacitor C, a DC magnetic deviation prevention means 3, and an inverter 4. The DC magnetic deviation prevention means 3 detects the coil currents I1, I2 flowing in the primary windings M1, M2 of the pulse transformer T. By controlling (shortening) the on time of the switching element having a greater amount of current, the coil currents I1, I2 are balanced (I1=I2), thereby preventing the magnetic deviation phenomena of the pulse transformer T.

Abstract: An apparatus for controlling the operation of power conditioners (10) for supplying the generated power to an external power system such as a commercial power system, in which power conditioners (10) are interconnected to an external power system, the power conditioners (10) are interconnected through information exchange means, at least one of the power conditioners (10) monitors the reverse power flow, and the power conditioners (10) exchange the monitor information with information of the other power conditioners (10), thereby equalizing the outputs of all the power conditioners (10). A generator (42) has armature windings (60), and an inverter circuit (13) of the power conditioner (10) provided for each of the armature windings (60) is controlled by cable or radio.

Abstract: An electric power conversion device comprises switching elements 2a, 2b making up a push-pull converter, a pulse transformer T, a rectification diode D1, a rectification diode D2, a choke coil L, a smoothing capacitor C, a DC magnetic deviation prevention means 3, and an inverter 4. The DC magnetic deviation prevention means 3 detects the coil currents I1, I2 flowing in the primary windings M1, M2 of the pulse transformer T. By controlling (shortening) the on time of the switching element having a greater amount of current, the coil currents I1, I2 are balanced (I1=I2), thereby preventing the magnetic deviation phenomena of the pulse transformer T.