Abstract: A solar cell power conversion device is disposed between a solar cell and a distribution system. A storage battery power conversion device is disposed between a storage battery and the distribution system. An effective voltage calculation circuit calculates an effective voltage of an AC voltage in the distribution system. Based on the effective voltage, a second control circuit and a fourth control circuit control active power and reactive power output from a first DC/AC conversion circuit and a second DC/AC conversion circuit, respectively. When a change in the effective voltage is caused by an operation of an SVR provided in the distribution system, the second and fourth control circuits control operations of the first and second DC/AC conversion circuits to suppress a change in the reactive power caused by the change in the effective voltage.

Abstract: A power conversion device inputs or outputs a power for changing a state quantity of a distribution grid to which a voltage source device is connected, to or from the distribution grid. A grid control unit calculates a power command value of the power conversion device such that a drooping characteristic is provided for compensating for a deviation from a control target of the state quantity obtained from an output of a detector. A frequency characteristic of control computation for calculating a power command value from the deviation in the system control unit is defined such that a first control gain value in a first frequency range including direct current is set corresponding to a slope of the drooping characteristic, and a second control gain value in a second frequency range including higher frequencies than the first frequency range is set to be lower than the first control gain value.

Abstract: A solar cell power conversion device is disposed between a solar cell and a consumer premises distribution system. A storage battery power conversion device is disposed between a storage battery and the consumer premises distribution system. When an AC effective voltage in the consumer premises distribution system deviates from a voltage range defined in accordance with dead zone information transmitted from HEMS, system voltage stabilization control for returning the AC effective voltage to fall within the voltage range is performed by control of active power and reactive power that are output from a first DC/AC conversion circuit and a second DC/AC conversion circuit.

Abstract: A solar cell power conversion device is disposed between a solar cell and a distribution system. A storage battery power conversion device is disposed between a storage battery and the distribution system. An effective voltage calculation circuit calculates an effective voltage of an AC voltage in the distribution system. Based on the effective voltage, a second control circuit and a fourth control circuit control active power and reactive power output from a first DC/AC conversion circuit and a second DC/AC conversion circuit, respectively. When a change in the effective voltage is caused by an operation of an SVR provided in the distribution system, the second and fourth control circuits control operations of the first and second DC/AC conversion circuits to suppress a change in the reactive power caused by the change in the effective voltage.

Abstract: The present invention includes a hunting determination unit configured to determine whether hunting has occurred or not for each of control devices in a power transmission and distribution system based on a control history of the control devices, a time constant calculation unit configured to calculate an adjustment time constant in which a time constant of the control device having state information indicating a state of the control device, with a high significance level, is increased, when the hunting determination unit determines that the hunting has occurred in one or more of the control devices, and a time constant transmission unit configured to transmit the adjustment time constant to the control device.

Abstract: A system state estimation device according to the present invention includes: a classification unit that classifies first meter data into a plurality of groups, the first meter data being meter data metered in a first time zone by at least some of a plurality of smart meters; a statistic calculation unit that calculates variation of the first meter data for each of the groups; used data determination unit that determines, for each of the groups, whether to use meter data in a second time zone or a substitute value in estimation computation for estimating a system state in the second time zone on the basis of the variation; and an aggregation unit and a power flow calculation unit that perform the estimation computation on the basis of a result of determination performed by the used data determination unit.

Abstract: Systems and methods are configured for detecting and locating simultaneous faults in a distribution network having primary and secondary buses connected with two-terminal sections. The measured three-phase voltages and currents from the primary buses are received via a communication network, and the series impedances and shunt admittances and the pre-fault connectivity topology are retrieved from the storage. Simultaneous faults are determined to occur by verifying at least one phase of at least three buses having phase current mismatches determined as the differences between the measured values and calculated values using normal topology and phase voltages that are greater than a threshold. A location for each fault is determined individually if the faults are occurring at non-adjacent sections in the distribution network, or jointly if the faults are occurring at adjacent sections in the distribution network.

Abstract: A solar cell power conversion device is disposed between a solar cell and a consumer premises distribution system. A storage battery power conversion device is disposed between a storage battery and the consumer premises distribution system. When an AC effective voltage in the consumer premises distribution system deviates from a voltage range defined in accordance with dead zone information transmitted from HEMS, system voltage stabilization control for returning the AC effective voltage to fall within the voltage range is performed by control of active power and reactive power that are output from a first DC/AC conversion circuit and a second DC/AC conversion circuit.

Abstract: Systems and methods are configured for detecting and locating simultaneous faults in a distribution network having primary and secondary buses connected with two-terminal sections. The measured three-phase voltages and currents from the primary buses are received via a communication network, and the series impedances and shunt admittances and the pre-fault connectivity topology are retrieved from the storage. Simultaneous faults are determined to occur by verifying at least one phase of at least three buses having phase current mismatches determined as the differences between the measured values and calculated values using normal topology and phase voltages that are greater than a threshold. A location for each fault is determined individually if the faults are occurring at non-adjacent sections in the distribution network, or jointly if the faults are occurring at adjacent sections in the distribution network.

Abstract: The present invention includes a hunting determination unit configured to determine whether hunting has occurred or not for each of control devices in a power transmission and distribution system based on a control history of the control devices, a time constant calculation unit configured to calculate an adjustment time constant in which a time constant of the control device having state information indicating a state of the control device, with a high significance level, is increased, when the hunting determination unit determines that the hunting has occurred in one or more of the control devices, and a time constant transmission unit configured to transmit the adjustment time constant to the control device.

Abstract: A current/voltage control apparatus capable of following power changes in a DC system. A current/voltage control apparatus includes a central monitoring control device that controls V-I characteristics of a terminal converter based on power consumption consumed by a load facility and generated power generated by a power generation facility, and the central monitoring control device includes a load state setting unit that predicts a change range of the power consumption in a predetermined period and also predicts a change range of the generated power in the period and a V-I characteristic determination unit that determines the V-I characteristics of the terminal converter based on the change range of the power consumption and the change range of the generated power predicted by the load state setting unit.

Abstract: A system state estimation device according to the present invention includes: a classification unit that classifies first meter data into a plurality of groups, the first meter data being meter data metered in a first time zone by at least some of a plurality of smart meters; a statistic calculation unit that calculates variation of the first meter data for each of the groups; used data determination unit that determines, for each of the groups, whether to use meter data in a second time zone or a substitute value in estimation computation for estimating a system state in the second time zone on the basis of the variation; and an aggregation unit and a power flow calculation unit that perform the estimation computation on the basis of a result of determination performed by the used data determination unit.

Abstract: A current/voltage control apparatus capable of following power changes in a DC system. A current/voltage control apparatus includes a central monitoring control device that controls V-I characteristics of a terminal converter based on power consumption consumed by a load facility and generated power generated by a power generation facility, and the central monitoring control device includes a load state setting unit that predicts a change range of the power consumption in a predetermined period and also predicts a change range of the generated power in the period and a V-I characteristic determination unit that determines the V-I characteristics of the terminal converter based on the change range of the power consumption and the change range of the generated power predicted by the load state setting unit.

Abstract: A transmitting circuit is connected to a power line at current flow-in sides to solar battery strings, and a receiving circuit is connected to the power line at current flow-out sides to the solar battery strings. An attenuating circuit connected in series to a bypass diode is provided in a bypass circuit. The transmitting circuit transmits a periodic signal of a predetermined frequency to the power line. The receiving circuit receives via the solar battery strings a transmission signal transmitted from the transmitting circuit to the power line. A determining circuit determines that, when it is detected that an amplitude of a transmission signal received by the receiving circuit is attenuated by a predetermined value or more, direct-current power is conducted to the bypass circuit.

Abstract: A transmitting circuit is connected to a power line at current flow-in sides to solar battery strings, and a receiving circuit is connected to the power line at current flow-out sides to the solar battery strings. An attenuating circuit connected in series to a bypass diode is provided in a bypass circuit. The transmitting circuit transmits a periodic signal of a predetermined frequency to the power line. The receiving circuit receives via the solar battery strings a transmission signal transmitted from the transmitting circuit to the power line. A determining circuit determines that, when it is detected that an amplitude of a transmission signal received by the receiving circuit is attenuated by a predetermined value or more, direct-current power is conducted to the bypass circuit.

Abstract: In a power system stabilization system for stabilizing a small-scale electric power system to which electric power generated by a rotating power generator is supplied, an electric water heater receives electric power from the electric power system and heats water, a system frequency measuring device measures system frequency of the electric power system, and a hot water controller increases the power consumption of the electric water heater when the system frequency exceeds a reference frequency, and decreases the power consumption of the electric water heater when the system frequency is less than the reference frequency.

Abstract: In a power system stabilization system for stabilizing a small-scale electric power system to which electric power generated by a rotating power generator is supplied, an electric water heater receives electric power from the electric power system and heats water, a system frequency measuring device measures system frequency of the electric power system, and a hot water controller increases the power consumption of the electric water heater when the system frequency exceeds a reference frequency, and decreases the power consumption of the electric water heater when the system frequency is less than the reference frequency.