Micro-grid combination control method based on inverter in energy storage unit

Abstract

The invention discloses a micro-grid combination control method based on an inverter in an energy storage unit. The control method is characterized in that inverter power supplies (of a micro-grid) which operate in a parallel manner before the micro-grid combination all adopt droop control policies; the inverter power supplies adopting the droop control policies adopt an operation mode of peer-to-peer control; a static switch which is used as a grid combination switch-on switch is adopted between the micro-grid and a power frequency power grid; the micro-grid combination control method comprises the following steps of: measuring and calculating a voltage amplitude value difference and a frequency difference at two sides of a public coupling point of the micro-grid and the power frequency power grid; adding the energy storage unit for adjusting so as to enable the voltage phase angle difference to meet voltage phase angle constraint conditions; closing a grid combination switch when all constraint conditions are met; and switching over inverter control policies of the energy storage unit to accomplish the whole process of the grid combination after the switch is closed. According to the method, the impact caused by the grid combination is reduced, and the micro-grid is smoothly combined into the power frequency power grid.

Description

technical field

[0001] The invention relates to the field of inverter control and grid connection, in particular to a method for controlling an inverter in an energy storage unit to realize grid connection of a microgrid. Background technique

[0002] In the traditional power system, the grid-connection condition is that the power grid waiting for grid-connection and the power frequency grid meet the voltage amplitude difference, voltage phase angle difference, and frequency difference at both ends of the public coupling point within a certain range, ensuring There is no excessive inrush current, and after the grid-connection is closed, the power grid to be paralleled can quickly enter synchronous operation. However, the microgrid contains a large number of inverter power supplies and power electronic devices, resulting in weak inertia of the microgrid and weak anti-disturbance ability of the microgrid. When the above requirements are met, the voltage and power may fluctuate...

Examples

Embodiment Construction

[0022] see Figure 4 , the method of this embodiment based on the microgrid grid-connected control of the inverter in the energy storage unit is: before the microgrid is connected to the grid, all the inverter power supplies running in parallel adopt the droop control strategy, and the inverter power supply adopting the droop control strategy is The operation mode of peer-to-peer control is adopted. The micro-grid system adopts the operation mode of peer-to-peer control, which means that all inverters in the micro-grid system are equal in status; each inverter supplies power to the load according to the output capacity, and the output capacity is specific. is the droop gain coefficient in its droop control.

[0023] Droop control is as formula (1) and (2):

[0024] ω=ω * -k p (P-P * ) (1)

[0025] E=E * -k q (Q-Q * ) (2)

[0026] In formula (1) and formula (2), P * , Q * is the reference value of active power and reactive power; P and Q are the output values ​​of ac...

technical field

[0001] The invention relates to the field of inverter control and grid connection, in particular to a method for controlling an inverter in an energy storage unit to realize grid connection of a microgrid. Background technique

[0002] In the traditional power system, the grid-connection condition is that the power grid waiting for grid-connection and the power frequency grid meet the voltage amplitude difference, voltage phase angle difference, and frequency difference at both ends of the public coupling point within a certain range, ensuring There is no excessive inrush current, and after the grid-connection is closed, the power grid to be paralleled can quickly enter synchronous operation. However, the microgrid contains a large number of inverter power supplies and power electronic devices, resulting in weak inertia of the microgrid and weak anti-disturbance ability of the microgrid. When the above requirements are met, the voltage and power may fluctuate...

Examples

Embodiment Construction

[0022] see Figure 4 , the method of this embodiment based on the microgrid grid-connected control of the inverter in the energy storage unit is: before the microgrid is connected to the grid, all the inverter power supplies running in parallel adopt the droop control strategy, and the inverter power supply adopting the droop control strategy is The operation mode of peer-to-peer control is adopted. The micro-grid system adopts the operation mode of peer-to-peer control, which means that all inverters in the micro-grid system are equal in status; each inverter supplies power to the load according to the output capacity, and the output capacity is specific. is the droop gain coefficient in its droop control.

[0023] Droop control is as formula (1) and (2):

[0024] ω=ω * -k p (P-P * ) (1)

[0025] E=E * -k q (Q-Q * ) (2)

[0026] In formula (1) and formula (2), P * , Q * is the reference value of active power and reactive power; P and Q are the output values ​​of ac...

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