Abstract: A startup method and startup program for microgrid that enable to stably start up the microgrid without producing frequency fluctuation is provided. An embodiment of the present disclosure is a startup method for microgrid configured by a plurality of inverter power supplies independently sharing a load and divided into a master that starts up first and a slave that starts up secondly and later, the startup method comprising: a master initial startup step of initially starting up the master in a CVCF mode; a slave initial startup step of initially starting up the slave in a grid interconnection mode; and a control mode changing step of the master and the slave changing control modes thereof when output fluctuation of the master and the slave becomes a predetermined threshold or less or when the master and the slave or other inverter power supplies become a predetermined operation state while output voltage of said master and said slave becomes a predetermined threshold or less.

Abstract: Provide is a power conversion device capable of avoiding a power outage even if reference AC power is lost. A power conversion device 1 includes a phase detector 31 calculating a voltage phase based on the phase of AC power supplied to an electric power system 9, a waveform controller 35 generating a control signal designating the frequency and phase of the AC power based on the voltage phase calculated by the phase detector 31, a power conversion circuitry 12 which converts power supplied from a power supply source 15 into the AC power based on the control signal generated by the waveform controller 35, and which outputs the converted power to the electric power system 9, and a determination block 44 which detects the frequency of the AC power supplied to the electric power system 9, and which determines that the AC power that becomes the reference for the frequency is not supplied to the electric power system 9 when the detected frequency is not within a preset first frequency range.

Abstract: Provided is a power converter capable of reducing cross current. The power converter 1 includes a phase controller 20 that calculate a phase angle reference value ?m based on a difference between a commanded active power reference value Pe and an output active power P supplied to a distribution line 5, a voltage controller 10 that calculates a voltage reference values Vu, Vv, and Vw based on the phase angle reference value ?m calculated by the phase controller 20, and a power conversion unit 52 that converts, based on the voltage reference values Vu, Vv, and Vw calculated by the voltage controller 10, an electric power supplied from a power supply source 60 into AC power and outputs it to the distribution line 5.

Abstract: A power supply system according to the present embodiment includes a plurality of first power converters configured to supply power according to dispatching characteristics of power to be supplied to a load, and a plurality of control devices each configured to associate a change ratio of active power to an output frequency of each of the first power converters with the dispatching characteristics and control each of the first power converters based on the change ratio.

Abstract: A remaining battery energy estimation device according to an embodiment includes a current corrector, an SOC calculator, a voltage estimator, an SOC correction amount determiner, and a current error estimator. The current corrector determines a corrected current value on the basis of a current value and a current correction amount of a storage battery. The SOC calculator calculates an estimated SOC value of the storage battery on the basis of the corrected current value and an SOC correction amount. The voltage estimator determines an estimated voltage value of the storage battery on the basis of a temperature value of the storage battery, the corrected current value, and the estimated SOC value. The SOC correction amount determiner determines the SOC correction amount on the basis of a comparison between a voltage value of the storage battery and the estimated voltage value. The current error estimator determines the current correction amount on the basis of the SOC correction amount.

Abstract: A power supply system according to the present embodiment includes a plurality of first power converters configured to supply power according to dispatching characteristics of power to be supplied to a load, and a plurality of control devices each configured to associate a change ratio of active power to an output frequency of each of the first power converters with the dispatching characteristics and control each of the first power converters based on the change ratio.

Abstract: A power supply system includes a plurality of power conversion devices, a plurality of breakers, and a controller. The plurality of breakers are respectively connected to the plurality of power conversion devices and configured to perform switching of an electrical connection between the power conversion device and a power system, wherein the breaker switches an ON state and an OFF state. The controller is configured to control the breakers and switch connection states of the plurality of power conversion devices are switched, and the controller being configured to determine whether or not the connected breaker is in an ON state and electrically conducted to the power system and the number of the power conversion devices in a standby state reaches a predetermined number.

Abstract: A power supply system according to an embodiment includes at least one or more inverter-connected power sources, a controller, and a current supplier. The inverter-connected power sources are connected to a power transmission line provided in an electric grid. The controller limits, based on output states of the inverter-connected power sources, current output from the inverter-connected power sources to the power transmission line. The current supplier is connected to the power transmission line in parallel with the inverter-connected power sources and when the controller limits the current output of the inverter-connected power sources, outputs a current to the power transmission line.

Abstract: A battery capacity estimation apparatus includes one or more hardware processors that: calculate a current integrated value by integrating electric currents of a secondary battery system whose capacity is to be estimated; calculate an SOC estimate value in a stabilization state where a change in SOC of a secondary battery per unit time is comparatively small; perform a regression analysis in which the current integrated value is defined as a dependent variable and the SOC estimate value is defined as an independent variable, the regression analysis being performed while correcting the current integrated value based on a value of a coefficient of determination so that a result of the regression analysis has predetermined accuracy; and estimate a capacity of the secondary battery system based on the result of the regression analysis.

Abstract: A reactive power control device includes a limit value deriver configured to derive a limit value of reactive power, which is output by one or a plurality of power conversion devices determined for system stabilization and control of a system voltage, on the basis of a voltage of a point other than a voltage control target, and a command value adjuster configured to adjust a reactive power command value for the one or plurality of power conversion devices on the basis of the limit value derived by the limit value deriver.

Abstract: A battery capacity estimation apparatus includes one or more hardware processors that: calculate a current integrated value by integrating electric currents of a secondary battery system whose capacity is to be estimated; calculate an SOC estimate value in a stabilization state where a change in SOC of a secondary battery per unit time is comparatively small; perform a regression analysis in which the current integrated value is defined as a dependent variable and the SOC estimate value is defined as an independent variable, the regression analysis being performed while correcting the current integrated value based on a value of a coefficient of determination so that a result of the regression analysis has predetermined accuracy; and estimate a capacity of the secondary battery system based on the result of the regression analysis.

Abstract: A remaining battery energy estimation device according to an embodiment includes a current corrector, an SOC calculator, a voltage estimator, an SOC correction amount determiner, and a current error estimator. The current corrector determines a corrected current value on the basis of a current value and a current correction amount of a storage battery. The SOC calculator calculates an estimated SOC value of the storage battery on the basis of the corrected current value and an SOC correction amount. The voltage estimator determines an estimated voltage value of the storage battery on the basis of a temperature value of the storage battery, the corrected current value, and the estimated SOC value. The SOC correction amount determiner determines the SOC correction amount on the basis of a comparison between a voltage value of the storage battery and the estimated voltage value. The current error estimator determines the current correction amount on the basis of the SOC correction amount.

Abstract: A power supply system includes a plurality of power conversion devices, a plurality of breakers, and a controller. The plurality of breakers are respectively connected to the plurality of power conversion devices and configured to perform switching of an electrical connection between the power conversion device and a power system, wherein the breaker switches an ON state and an OFF state. The controller is configured to control the breakers and switch connection states of the plurality of power conversion devices are switched, and the controller being configured to determine whether or not the connected breaker is in an ON state and electrically conducted to the power system and the number of the power conversion devices in a standby state reaches a predetermined number.

Abstract: A reactive power control device includes a limit value deriver configured to derive a limit value of reactive power, which is output by one or a plurality of power conversion devices determined for system stabilization and control of a system voltage, on the basis of a voltage of a point other than a voltage control target, and a command value adjuster configured to adjust a reactive power command value for the one or plurality of power conversion devices on the basis of the limit value derived by the limit value deriver.