Control circuit for an invertor operable in an individual mode and an interconnection mode

Claim 2

A control circuit for a voltage invertor for converting DC voltage to AC voltage operable in an individual mode and an interconnection mode, said control circuit comprising an individual control system in which the AC voltage is controlled in a constant-voltage and individually supplied to a load; a synchronous-interconnection control system for controlling an amplitude and a phase of an output voltage of said voltage invertor to synchronize them with those in a power system and incorporating said invertor into the power system; and an effective power control system and a reactive power control system for controlling the effective component and the reactive component of an electric power transferred between the power system and said invertor interconnected with the power system, thereby to perform the interconnection mode operation; said control circuit serving also as a voltage adjuster for making a constant-voltage control or a synchronous control of said AC voltage, said control circuit further comprising: a synchronous compensating circuit in which when said invertor is operating in a power system synchronous operation mode under control of said synchronous-interconnection control system, a quantity of an instantaneous voltage variation occurring in the power system is detected in terms of a quantity of the component in phase with a reference voltage vector as the vector of the output voltage of said invertor, and a quantity of the orthogonal component orthogonal to said reference voltage vector, and the detected variation quantities are respectively added to the outputs of a voltage adjuster and a phase adjuster in said synchronous-interconnection control system.

Claim 3

A control circuit as claimed in claim 1, wherein said synchronous compensating circuit comprises: first 3-phase/2-phase converter for separating the output voltage of the voltage invertor into in-phase component and an orthogonal component; second 3-phase/2-phase converter for separating the voltage of the power system into an in-phase component and an orthogonal component; vector analyzer for preparing a reference vector of the invertor voltage on the basis of an output voltage of the first 3-phase/2-phase converter; vector drainer for separately outputting a quantity of a variation of the output voltage of the second converter in the in-phase component and the orthogonal component; first adding means for adding an output of the vector drainer of the in-phase component to the output voltage of the voltage adjuster; second adding means for adding an output of the vector drainer of the orthogonal component to the output voltage of the phase adjuster.

Claim 4

A control circuit for a voltage invertor for converting DC voltage to AC voltage operable in an individual mode and an interconnection mode, said control circuit comprising an individual control system in which the AC voltage is controlled in a constant-voltage and individually supplied to a load; a synchronous-interconnection control system for controlling an amplitude and a phase of an output voltage of said voltage invertor to synchronize them with those in a power system and incorporating said invertor into the power system; and an effective power control system and a reactive power control system for controlling the effective component and the reactive component of an electric power transferred between the power system and said invertor interconnected with the power system, thereby to perform the interconnection mode operation; said control circuit serving also as a voltage adjuster for making a constant-voltage control or a synchronous control of said AC voltage, said control circuit further comprising: an interconnection mode compensating circuit in which the output voltage of said invertor, which is operating in the interconnection mode under control of said effective power control system and said reactive power control system, is stored as an internal vector, a quantity of an instantaneous variation in the voltage of the power system is detected in terms of a quantity of a variation of the component in phase with said internal vector and a quantity of a variation of the component orthogonal to the internal vector, and the detected variation quantities are respectively added to the voltage-converted outputs of said effective power control system and said reactive power control system.

Claim 5

A control circuit for a voltage invertor for converting DC voltage to AC voltage operable in an individual mode and an interconnection mode, said control circuit comprising an individual control system in which the AC voltage is controlled in a constant-voltage and individually supplied to a load; a synchronous-interconnection control system for controlling an amplitude and a phase of an output voltage of said voltage invertor to synchronize them with those in a power system and incorporating said invertor into the power system; and an effective power control system and a reactive power control system for controlling the effective component and the reactive component of an electric power transferred between the power system and said invertor interconnected with the power system, thereby to perform the interconnection mode operation; said control circuit serving also as a voltage adjuster for making a constant-voltage control or a synchronous control of said AC voltage, said control circuit further comprising: an interconnection mode compensating circuit in which the output voltage of said invertor, which is operating in the interconnection mode under control of said effective power control system and said reactive power control system, is stored as an internal vector, a quantity of an instantaneous variation in the voltage of the power system is detected in terms of a quantity of a variation of the component in phase with said internal vector and a quantity of a variation of the component orthogonal to the internal vector, and the detected variation quantities are respectively added to the voltage-converted outputs of said effective power control system and said reactive power control system.

Claim 6

A control circuit as claimed in claim 3, wherein interconnection compensating circuit comprises: synchronous signal generation for temporarily storing a power system voltage to generate an internal reference vector with a predetermined delay time; 3-phase/2-phase converter for separating the voltage of the power system into an in-phase component and an orthogonal component; vector drainer for separately outputting a quantity of a variation of the output voltage of the converter in the in-phase component and the orthogonal component; first adding means for adding an output of the vector drainer of the in-phase component to the output voltage of the effective power control system; second adding means for adding an output of the vector drainer of the orthogonal component to the output voltage of the reactive power control system.

Claim 7

A control circuit for a voltage invertor for converting DC voltage to AC voltage operable in an individual mode and an interconnection mode, said control circuit comprising an individual control system in which the AC voltage is controlled in a constant-voltage and individually supplied to a load; a synchronous-interconnection control system for controlling an amplitude and a phase of an output voltage of said voltage invertor to synchronize them with those in a power system and incorporating said invertor into the power system; and an effective power control system and a reactive power control system for controlling the effective component and the reactive component of an electric power transferred between the power system and said invertor interconnected with the power system, thereby to perform the interconnection mode operation; said control circuit serving also as a voltage adjuster for making a constant-voltage control or a synchronous control of said AC voltage, said control circuit further comprising: a synchronous-interconnection mode compensating circuit in which the output voltage of said invertor, which is operating in the power system synchronous-interconnection mode or the interconnection mode, is stored as an internal vector, a quantity of an instantaneous variation in the voltage of the power system is detected in terms of a quantity of a variation of the component in phase with said internal vector and a quantity of a variation of the component orthogonal to the internal vector, and the detected variation quantities are respectively added to the outputs of said effective power control system and said reactive power control system or the outputs of said synchronous-interconnection control system.

Claim 8

A control circuit for a voltage invertor for converting DC voltage to AC voltage operable in an individual mode and an interconnection mode, said control circuit comprising an individual control system in which the AC voltage is controlled in a constant-voltage and individually supplied to a load; a synchronous-interconnection control system for controlling an amplitude and a phase of an output voltage of said voltage invertor to synchronize them with those in a power system and incorporating said invertor into the power system; and an effective power control system and a reactive power control system for controlling the effective component and the reactive component of an electric power transferred between the power system and said invertor interconnected with the power system, thereby to perform the interconnection mode operation; said control circuit serving also as a voltage adjuster for making a constant-voltage control or a synchronous control of said AC voltage, said control circuit further comprising: a synchronous-interconnection mode compensating circuit in which the output voltage of said invertor, which is operating in the power system synchronous-interconnection mode or the interconnection mode, is stored as an internal vector, a quantity of an instantaneous variation in the voltage of the power system is detected in terms of a quantity of a variation of the component in phase with said internal vector and a quantity of a variation of the component orthogonal to the internal vector, and the detected variation quantities are respectively added to the outputs of said effective power control system and said reactive power control system or the outputs of said synchronous-interconnection control system.

Claim 9

A control circuit as claimed in claim 5, wherein said synchronous-interconnection compensating circuit comprises: synchronous signal generation for temporarily storing a power system voltage to generate an internal reference vector with a predetermined delay time; 3-phase/2-phase converter for separating the voltage of the power system into an in-phase component and an orthogonal component; vector drainer for separately outputting a quantity of a variation of the output voltage of the converter in the in-phase component and the orthogonal component; vector analyzer for preparing a reference vector of the invertor voltage on the basis of an output voltage of the 3-phase/2-phase converter; subtractor for subtracting the output voltage of the vector analyzer from the in-phase component of the output of the vector drainer; first adding means for adding an output of the subtractor to the output voltage of the effective power control system; second adding means for adding an output of the vector drainer of the orthogonal component to the output voltage of the reactive power control system.