Abstract: A flying capacitor (FC)-type 3-level power conversion device turns on or off first to fourth semiconductor switching elements based on comparison between a flying capacitor voltage and a half of higher-voltage side filter capacitor voltage, comparison between the higher-voltage side filter capacitor voltage and the flying capacitor voltage plus a lower-voltage side filter capacitor voltage, comparison between the flying capacitor voltage and the lower-voltage side filter capacitor voltage, and comparison between the lower-voltage side filter capacitor voltage or the higher-voltage side filter capacitor voltage and a filter capacitor voltage command value, so that an electric current flows along a path including a filter reactor L and charging a flying capacitor so as to charge a lower-voltage side filter capacitor or a higher-voltage side filter capacitor to predetermined values.

Abstract: A flying capacitor (FC)-type 3-level power conversion device turns on or off first to fourth semiconductor switching elements based on comparison between a flying capacitor voltage and a half of higher-voltage side filter capacitor voltage, comparison between the higher-voltage side filter capacitor voltage and the flying capacitor voltage plus a lower-voltage side filter capacitor voltage, comparison between the flying capacitor voltage and the lower-voltage side filter capacitor voltage, and comparison between the lower-voltage side filter capacitor voltage or the higher-voltage side filter capacitor voltage and a filter capacitor voltage command value, so that an electric current flows along a path including a filter reactor L and charging a flying capacitor so as to charge a lower-voltage side filter capacitor or a higher-voltage side filter capacitor to predetermined values.

Abstract: A flying capacitor (FC)-type 3-level power conversion device turns on or off first to fourth semiconductor switching elements based on comparison between a flying capacitor voltage and a half of higher-voltage side filter capacitor voltage, comparison between the higher-voltage side filter capacitor voltage and the flying capacitor voltage plus a lower-voltage side filter capacitor voltage, comparison between the flying capacitor voltage and the lower-voltage side filter capacitor voltage, and comparison between the lower-voltage side filter capacitor voltage or the higher-voltage side filter capacitor voltage and a filter capacitor voltage command value, so that an electric current flows along a path including a filter reactor L and charging a flying capacitor so as to charge a lower-voltage side filter capacitor or a higher-voltage side filter capacitor to predetermined values.

Abstract: An FC-type 3-level power conversion device turns on or off first to fourth semiconductor switching elements based on comparison between a flying capacitor voltage and a half of higher-voltage side filter capacitor voltage, comparison between the higher-voltage side filter capacitor voltage and the flying capacitor voltage plus a lower-voltage side filter capacitor voltage, comparison between the flying capacitor voltage and the lower-voltage side filter capacitor voltage, and comparison between the lower-voltage side filter capacitor voltage or the higher-voltage side filter capacitor voltage and a filter capacitor voltage command value, so that an electric current flows along a path including a filter reactor L and charging a flying capacitor so as to charge a lower-voltage side filter capacitor or a higher-voltage side filter capacitor to predetermined values.

Abstract: To provide a dc interruption apparatus requiring no circuit for producing current zero point forcibly and having a simplified construction adequate for cost reduction, one end of a main contact 30a, 30b, 30c for each phase of a dc high speed vacuum circuit breaker 30 is connected with a positive output end of a corresponding phase of a rectifier 20 for converting ac power to dc power with semiconductor devices arranged in a bridge. The other ends of the main contacts 30a, 30b, 30c are connected together to form a positive side output line 40. A pulse-shaped current flows in an arm of each phase of the rectifier 20 and the current is commutated among the arms sequentially, so that the current is reduced to zero after the commutation. Each of main contacts 30a, 30b, 30c of dc high speed vacuum circuit breaker 30 interrupts the current reduced to zero by the commutation, so that the interruption is easier.

Abstract: To provide a dc interruption apparatus requiring no circuit for producing current zero point forcibly and having a simplified construction adequate for cost reduction, one end of a main contact 30a, 30b, 30c for each phase of a dc high speed vacuum circuit breaker 30 is connected with a positive output end of a corresponding phase of a rectifier 20 for converting ac power to dc power with semiconductor devices arranged in a bridge. The other ends of the main contacts 30a, 30b, 30c are connected together to form a positive side output line 40. A pulse-shaped current flows in an arm of each phase of the rectifier 20 and the current is commutated among the arms sequentially, so that the current is reduced to zero after the commutation. Each of main contacts 30a, 30b, 30c of dc high speed vacuum circuit breaker 30 interrupts the current reduced to zero by the commutation, so that the interruption is easier.

Abstract: In a torque ripple suppression control effected by a periodicity disturbance observer, it is necessary to consider plant fluctuation and fluctuation of plant characteristics caused by over time usage. Thus, improvement for robustness to an identification model error has been required.

Abstract: A current control unit takes a deviation between a current command value and a current flowing through an inverter of a power conversion device, and controls the inverter based on the deviation. A harmonic sensing part receives input of an output current of an AC filter, and outputs a predetermined order harmonic of the input current in a direct current value form. A disturbance observer estimates the disturbance of the harmonic based on the output current and a coefficient defined as an inverse function of a transfer function from harmonic suppression current command value to filter output current detection value. A harmonic suppression control unit takes the deviation between the estimated harmonic disturbance and a disturbance command value that suppresses the disturbance, and calculates a harmonic suppression current command value. The harmonic suppression current command value is superimposed on the current command value of the current control unit.

Abstract: In a torque ripple suppression control effected by a periodicity disturbance observer, it is necessary to consider plant fluctuation and fluctuation of plant characteristics caused by over time usage. Thus, improvement for robustness to an identification model error has been required.

Abstract: A system stabilizing device disposed in a micro grid incorporates a self-supporting control unit (200). The self-supporting control unit (200) allows a dq transforming unit (201) to determine an effective system voltage Vsd and an ineffective system voltage Vsq from a system voltage Vs. A fluctuation detecting unit (202) has differential characteristics and first-order lag characteristics, and determines the fluctuation component of the effective system voltage Vsd. This fluctuation component is multiplied by a gain in a proportional computing unit (203) to determine an ineffective current command Irefq. A fluctuation detecting unit (204) does not have differential characteristics, but has first-order lag characteristics, and determines the fluctuation component of the ineffective system voltage Vsq. This fluctuation component is multiplied by a gain in a proportional computing unit (205) to determine an effective current command Irefd.

Abstract: A control unit of a system stabilization device uses a fluctuation detection block (60) to determine fluctuation components included in the active component and reactive component currents of a system current and fluctuation components included in the frequency signal and the amplitude signal of a system voltage. The high frequency cut-off of the fluctuation detection block (60) is set to be f1; the low frequency cut-off is set to be f2. The fluctuation detection block (60) is composed of a low-pass filter (61) with a time constant of T1, a low-pass filter (62) with a time constant of T2, a subtracter (63) which outputs the difference, between the output signals of the filter (61) and the filter (62), and a feedback circuit (64) which provides feedback on the output of the subtracter (63) to the filters (61, 62). Thus, stability is ensured without using a current detector.

Abstract: A self-contained control unit of a system stabilizing device installed on a microgrid is provided with a fluctuation detecting block 70A for determining a fluctuation component of the frequency of system voltage (C?s) and a fluctuation component of voltage amplitude of the system voltage (C|Vs|). The fluctuation detecting block 70A determines the fluctuation component (C?s) based on a deviation between the output signal of a low-pass filter 71 for noise removal and the output signal of a low-pass filter 72 for determining a fluctuation detection time. An interference action inhibiting unit 100 judges whether system stabilizing control and governor control of a generator interfere with each other, based on a frequency signal ?s and the fluctuation component C?s. If there is interference, the time constant of the low-pass filter 72 is reduced to reduce the fluctuation component C?s, thereby decreasing the amount of control by the system stabilizing device and preventing interference.

Abstract: A control unit of a system stabilizing device uses a fluctuation detecting block (70A) to determine fluctuation components included in the active component and reactive component currents of a system current. The fluctuation detecting block (70A) is composed of a low-pass filter (71) for noise removal having first order lag characteristics with a time constant of T1, a low-pass filter (72) for setting a fluctuation detection time having first order lag characteristics with a time constant of T2, a subtracter (73) which performs subtraction between the output signals of the filter (71) and the filter (72) and outputs the difference, an amplifier (74) for amplifying the output of the subtracter (73), a rating limiter (75) for limiting the output of the amplifier, and an overcompensation inhibiting unit (200) which changes T4 to a smaller value when the rating limiter (75) performs a limiter action.

Abstract: A current control unit takes a deviation between a current command value and a current flowing through an inverter of a power conversion device, and controls the inverter based on the deviation. A harmonic sensing part receives input of an output current of an AC filter, and outputs a predetermined order harmonic of the input current in a direct current value form. A disturbance observer estimates the disturbance of the harmonic based on the output current and a coefficient defined as an inverse function of a transfer function from harmonic suppression current command value to filter output current detection value. A harmonic suppression control unit takes the deviation between the estimated harmonic disturbance and a disturbance command value that suppresses the disturbance, and calculates a harmonic suppression current command value. The harmonic suppression current command value is superimposed on the current command value of the current control unit.

Abstract: A control unit of a system stabilizing device uses a fluctuation detecting block 200 for determining current commands from a system current. A fluctuation detecting unit 300 determines, from an active component Isd of the system current, a common current command Irefd0 which is a fluctuation component of the active component Isd. A first current command creating unit 400 receives as an input the current command Irefd0, and outputs a current command Irefd1 whose signal width is as small as T4 and which instantaneously rises and then gradually decreases. A second current command creating unit 500 receives as an input the current command Irefd0, and outputs a current command Irefd2 which gradually increases for a time T4 and then gradually decreases for a time (T3-T4).

Abstract: A system stabilizing device disposed in a micro grid incorporates a self-supporting control unit (200). The self-supporting control unit (200) allows a dq transforming unit (201) to determine an effective system voltage Vsd and an ineffective system voltage Vsq from a system voltage Vs. A fluctuation detecting unit (202) has differential characteristics and first-order lag characteristics, and determines the fluctuation component of the effective system voltage Vsd. This fluctuation component is multiplied by a gain in a proportional computing unit (203) to determine an ineffective current command Irefq. A fluctuation detecting unit (204) does not have differential characteristics, but has first-order lag characteristics, and determines the fluctuation component of the ineffective system voltage Vsq. This fluctuation component is multiplied by a gain in a proportional computing unit (205) to determine an effective current command Irefd.

Abstract: A control unit of a system stabilizing device uses a fluctuation detecting block 200 for determining current commands from a system current. A fluctuation detecting unit 300 determines, from an active component Isd of the system current, a common current command Irefd0 which is a fluctuation component of the active component Isd. A first current command creating unit 400 receives as an input the current command Irefd0, and outputs a current command Irefd1 whose signal width is as small as T4 and which instantaneously rises and then gradually decreases. A second current command creating unit 500 receives as an input the current command Irefd0, and outputs a current command Irefd2 which gradually increases for a time T4 and then gradually decreases for a time (T3-T4).

Abstract: A self-contained control unit of a system stabilizing device installed on a microgrid is provided with a fluctuation detecting block 70A for determining a fluctuation component of the frequency of system voltage (C?s) and a fluctuation component of voltage amplitude of the system voltage (C|Vs|). The fluctuation detecting block 70A determines the fluctuation component (C?s) based on a deviation between the output signal of a low-pass filter 71 for noise removal and the output signal of a low-pass filter 72 for determining a fluctuation detection time. An interference action inhibiting unit 100 judges whether system stabilizing control and governor control of a generator interfere with each other, based on a frequency signal ?s and the fluctuation component C?s. If there is interference, the time constant of the low-pass filter 72 is reduced to reduce the fluctuation component C?s, thereby decreasing the amount of control by the system stabilizing device and preventing interference.

Abstract: A control unit of a system stabilizing device uses a fluctuation detecting block (70A) to determine fluctuation components included in the active component and reactive component currents of a system current. The cut-off frequency on the high frequency side of the fluctuation detecting block (70A) is set to be f1; the cut-off frequency on the low frequency side is set to be f2; the time constant of a low-pass filter for noise removal which has a cut-off frequency of f1 is set to be T1; and the time constant of a low-pass filter for setting a fluctuation detection time which has a cut-off frequency of f2 is set to be T2.

Abstract: A control unit of a system stabilization device uses a fluctuation detection block (60) to determine fluctuation components included in the active component and reactive component currents of a system current and fluctuation components included in the frequency signal and the amplitude signal of a system voltage. The cut-off frequency on the high frequency side of the fluctuation detection block (60) is set to be f1; the cut-off frequency on the low frequency side is set to be f2; the time constant of the low-pass filter for noise removal which has a cut-off frequency of f1 is set to be T1; and the time constant of the low-pass filter for setting a fluctuation detection time which has a cut-off frequency of f2 is set to be T2.