Grid system, control device, control method for grid system, and power conversion device

A control device for controlling at least one of a plurality of consumers connected to a voltage source via a distribution grid, based on a power command value from a grid controller connected to each of the plurality of consumers,

• the at least one of the plurality of consumers including
• a power generation device connected to a power receiving point which is a connection point with the distribution grid,
• a power storage device connected to the power receiving point,
• a first power converter which is provided between the power generation device and the power receiving point, and which converts an output voltage of the power generation device to a predetermined AC voltage, and
• a second power converter which is provided between the power storage device and the power receiving point, and which converts an output voltage of the power storage device to another predetermined AC voltage,
• the control device comprising:
• a power command corrector to correct the power command value from the grid controller on the basis of a frequency of voltage at the power receiving point;
• and
• a power controller to control the first power converter and the second power converter respectively based on different power command values corrected by the power command corrector, wherein
• the power command value for controlling the first power converter is set to be greater than the power command value for controlling the second power converter,
• the first power converter includes a first reactive power command corrector to, when voltage of the at least one consumer becomes greater than a first predetermined voltage set in advance or becomes smaller than a second predetermined voltage set in advance, output a reactive power corresponding to a difference from the first predetermined voltage or the second predetermined voltage, and
• the second power converter includes a second reactive power command corrector to, when the voltage of the at least one consumer becomes greater than a third predetermined voltage set in advance or smaller than a fourth predetermined voltage set in advance, output a reactive power corresponding to a difference from the third predetermined voltage or the fourth predetermined voltage.

A control method for a grid system including a voltage source, a plurality of consumers each connected to the voltage source via a distribution grid, and a grid controller to transmit a power command value to each of the plurality of consumers, the method comprising:

• acquiring a frequency of a voltage at a power receiving point which is a connection point between the device and the distribution grid;
• correcting the power command value from the grid controller based on the frequency of the voltage at the power receiving point;
• converting an output voltage of a power generation device included in at least one consumer of the plurality of consumers and connected to the voltage source to a value of an AC voltage based on the corrected first power command value;
• converting an output voltage of a power storage device included in the at least one consumer of the plurality of consumers and connected to the voltage source to a value of the AC voltage based on a second power command value having a smaller value than the corrected first power command value;
• when voltage of the at least one consumer becomes greater than a first predetermined voltage set in advance or becomes smaller than a second predetermined voltage set in advance, outputting a reactive power corresponding to a difference from the first predetermined voltage or the second predetermined voltage;
• and
• when the voltage of the at least one consumer becomes greater than a third predetermined voltage set in advance or smaller than a fourth predetermined voltage set in advance, outputting a reactive power corresponding to a difference from the third predetermined voltage or the fourth predetermined voltage.

A power conversion device used in a grid system including a voltage source, a plurality of consumers connected to the voltage source via a distribution grid, and a grid controller to transmit a power command value to each of the plurality of consumers, the power conversion device having an end connected to the distribution grid via a power receiving point, and another end connected to a power generation device or a power storage device, the power conversion device comprising:

• a power converter to convert an output DC voltage of the power generation device or the power storage device to a predetermined AC voltage;
• and
• a controller to control the power converter based on the power command value transmitted from the grid controller, wherein
• the controller includes
• a power command corrector to correct the power command value transmitted from the grid controller, based on a frequency of voltage at the power receiving point,
• a power controller to control the power converter based on the power command value corrected by the power command corrector, and
• a reactive power command corrector,
• when the power generation device is connected,
• the power command corrector corrects the transmitted power command value so as to be increased, and
• when voltage of the at least one consumer becomes greater than a first predetermined voltage set in advance or becomes smaller than a second predetermined voltage set in advance, the reactive power command corrector outputs a reactive power corresponding to a difference from the first predetermined voltage or the second predetermined voltage, and
• when the power storage device is connected,
• the power command corrector corrects the transmitted power command value so as to be decreased, and
• when the voltage of the at least one consumer becomes greater than a third predetermined voltage set in advance or smaller than a fourth predetermined voltage set in advance, the reactive power command corrector outputs a reactive power corresponding to a difference from the third predetermined voltage or the fourth predetermined voltage.