Electric power converter, control method for electric power converter, electric power system, control method for electric power system, and computer readable recording medium
An electric power converter for being electrically connected to a commercial power system of alternating current type and electrically connected to a device configured to input and/or output electric power. The converter includes a control unit configured to perform primary control of the device based on a reference function which has drooping characteristic for generating target value when local-control of the device is implemented according to voltage measured by the electric power converter. The electric power converter is further controlled according to secondary control in which the reference function having the drooping characteristic is updated according to electric power status of an electric power system in which the electric power converter is installed, and control cycle of the primary control is different from control cycle of the secondary control.
1 . An electric power converter configured to be electrically connected to a commercial power system of alternating current type and electrically connected to a device configured to input and/or output electric power, the electric power converter comprising:
a control unit configured to perform primary control of the device based on a reference function which has a drooping characteristic for generating a target value when local-control of the device is implemented according to a voltage measured by the electric power converter,
wherein the electric power converter is further controlled according to secondary control in which the reference function having the drooping characteristic is updated according to an electric power status of an electric power system in which the electric power converter is installed,
wherein a control cycle of the primary control is different from a control cycle of the secondary control,
wherein the secondary control is either performed by a central control unit included in the electric power system and configured to execute the secondary control, or performed by at least one of a plurality of electric power converters included in the electric power system and configured to execute the secondary control for all of the plurality of electric power converters, the electric power converter being one of the plurality of electric power converters included in the electric power system,
wherein the primary control is performed based on a voltage of the device,
wherein the secondary control is controlled based on a relationship between a discharge amount of electric power discharged from a line connected to the electric power converter and a received amount of electric power received by the line, and
wherein the central control unit or the power converter executing the secondary control is configured to calculate the discharge amount and the received amount from local measurement information of each of the power converters, and transmit the updated reference function when it is determined that the reference function needs to be updated, and each of the power converters is configured to execute the primary control using the updated reference function.
2 . The electric power converter according to claim 1 , wherein
the electric power system comprises the central control unit configured to control the plurality of the electric power converters, and
the secondary control is performed based on a command issued by the central control unit.
3 . The electric power converter according to claim 1 , wherein the primary control is performed based on the voltage of the device, without involving a command from a central control unit configured to control a plurality of the electric power converters.
4 . The electric power converter according to claim 1 , wherein the reference function having the drooping characteristic is configured to vary an input-output amount of electric power or electric current according to variation in voltage.
5 . The electric power converter according to claim 1 , wherein the secondary control includes updating the reference function having the drooping characteristic in such a way that electric power of the device becomes constant.
6 . The electric power converter according to claim 1 , wherein the control cycle of the secondary control is longer than the control cycle of the primary control.
7 . The electric power converter according to claim 1 , wherein the electric power converter is a DC/DC converter.
8 . The electric power converter according to claim 1 , wherein, at least one of the plurality of electric power converters is configured to function as a central control unit configured to execute the secondary control of the plurality of electric power converters.
9 . An electric power system comprising:
a plurality of electric power elements electrically connected to a commercial power system of alternating current type, each electric power element including an electric power converter and a device electrically connected to the electric power converter, wherein:
the electric power converter includes a control unit configured to perform primary control based on a reference function having a drooping characteristic for generating a target value when local-control of the device is implemented according to a voltage measured by the electric power converter,
the electric power system is equipped with function of secondary control in which the reference function having the drooping characteristic is updated according to an electric power status of the plurality of electric power elements,
a control cycle of the primary control is different from a control cycle of the secondary control,
the secondary control is either performed by a central control unit included in the electric power system and configured to execute the secondary control, or performed by at least one of a plurality of electric power converters included in the electric power system and configured to execute the secondary control for all of the plurality of electric power converters, the electric power converter being one of the plurality of electric power converters included in the electric power system,
the primary control is performed based on a voltage of the device,
the secondary control is controlled based on a relationship between a discharge amount of electric power discharged from a line connected to the electric power converter and a received amount of electric power received by the line, and
the central control unit or the power converter executing the secondary control is configured to calculate the discharge amount and the received amount from local measurement information of each of the power converters, and transmit the updated reference function when it is determined that the reference function needs to be updated, and each of the power converters is configured to execute the primary control using the updated reference function.
10 . The electric power system according to claim 9 , further comprising the central control unit configured to control the plurality of the electric power converter, wherein
the secondary control is performed based on a command issued by the central control unit.
11 . The electric power system according to claim 9 , wherein the primary control is performed based on the voltage of the device, without involving a command from a central control unit configured to control a plurality of the electric power converter.
12 . The electric power system according to claim 9 , wherein the reference function having the drooping characteristic is configured to vary an input-output amount of electric power or electric current according to variation in voltage.
13 . The electric power system according to claim 9 , wherein the secondary control includes updating the reference function having the drooping characteristic in such a way that electric power of devices of the electric power elements becomes constant.
14 . The electric power system according to claim 9 , wherein the control cycle of the secondary control is longer than the control cycle of the primary control.
15 . The electric power system according to claim 9 , wherein a line on which the electric power elements are electrically connected is a DC bus.
16 . The electric power system according to claim 10 , wherein, at least one of the plurality of electric power converters is configured to function as a central control unit configured to execute the secondary control of the plurality of electric power converters.
17 . A control method for an electric power converter electrically connected to a commercial power system of alternating current type and electrically connected to a device configured to input and/or output electric power, the control method comprising:
performing primary control of the device based on a reference function having a drooping characteristic for generating target value when local-control of the device is implemented according to a voltage measured by the electric power converter; and
controlling the electric power converter according to secondary control in which the reference function having the drooping characteristic is updated according to an electric power status of an electric power system in which the electric power converter is installed, wherein:
a control cycle of the primary control is different from a control cycle of the secondary control,
the secondary control is either performed by a central control unit included in the electric power system and configured to execute the secondary control, or performed by at least one of a plurality of electric power converters included in the electric power system and configured to execute the secondary control for all of the plurality of electric power converters, the electric power converter being one of the plurality of electric power converters included in the electric power system,
the primary control is performed based on a voltage of the device,
the secondary control is controlled based on a relationship between a discharge amount of electric power discharged from a line connected to the electric power converter and a received amount of electric power received by the line, and
the central control unit or the power converter executing the secondary control is configured to calculate the discharge amount and the received amount from local measurement information of each of the power converters, and transmit the updated reference function when it is determined that the reference function needs to be updated, and each of the power converters is configured to execute the primary control using the updated reference function.
18 . A control method for an electric power system including a plurality of electric power elements, each including: an electric power converter electrically connected to a commercial power system of alternating current type; and a device electrically connected to the electric power converter, the control method comprising:
performing primary control based on a reference function which has drooping characteristic for generating target value when local-control of the device is implemented according to a voltage measured by the electric power converter; and
performing secondary control in which the reference function having the drooping characteristic is updated according to an electric power status of the plurality of electric power elements, wherein:
a control cycle of the primary control is different from a control cycle of the secondary control,
the secondary control is either performed by a central control unit included in the electric power system and configured to execute the secondary control, or performed by at least one of a plurality of electric power converters included in the electric power system and configured to execute the secondary control for all of the plurality of electric power converters, the electric power converter being one of the plurality of electric power converters included in the electric power system,
the primary control is performed based on a voltage of the device,
the secondary control is controlled based on a relationship between a discharge amount of electric power discharged from a line connected to the electric power converter and a received amount of electric power received by the line, and
the central control unit or the power converter executing the secondary control is configured to calculate the discharge amount and the received amount from local measurement information of each of the power converters, and transmit the updated reference function when it is determined that the reference function needs to be updated, and each of the power converters is configured to execute the primary control using the updated reference function.
19 . A control method for an electric power system including: a plurality of electric power elements, each including an electric power converter electrically connected to a commercial power system of alternating current type and including a device electrically connected to the electric power converter; and a central control device configured to communicate information with the plurality of electric power converters and with an external server which holds demand information about demand of electric power, the control method comprising:
performing primary control based on a reference function having drooping characteristic for generating target value when local-control of the device is implemented according to a voltage measured by the electric power converter;
obtaining the demand information from the external server; and
performing secondary control in which the reference function having the drooping characteristic is updated according to an electric power status of the plurality of electric power elements and according to the demand information, wherein:
a control cycle of the primary control is different than a control cycle of the secondary control,
the secondary control is either performed by a central control unit included in the electric power system and configured to execute the secondary control, or performed by at least one of a plurality of electric power converters included in the electric power system and configured to execute the secondary control for all of the plurality of electric power converters, the electric power converter being one of the plurality of electric power converters included in the electric power system,
the primary control is performed based on a voltage of the device,
the secondary control is controlled based on a relationship between a discharge amount of electric power discharged from a line connected to the electric power converter and a received amount of electric power received by the line, and
the central control unit or the power converter executing the secondary control is configured to calculate the discharge amount and the received amount from local measurement information of each of the power converters, and transmit the updated reference function when it is determined that the reference function needs to be updated, and each of the power converters is configured to execute the primary control using the updated reference function.