Grid-connected power control method of electric power system

Abstract

A grid-connected power control method of a power system relates to the field of power regulation and lacks effective regulation of reactive power in the prior art. The method comprises the following steps: acquiring capacitor-side output voltage and load-side output current in a grid-connected inverter system to obtain inverter instantaneous active power and inverter instantaneous reactive power; the difference value between the reactive reference power and the instantaneous reactive power of the inverter is input into a first PID module; the difference value between the active reference power and the instantaneous active power of the inverter is input to a second PID module; the output value adjusted by the first PID module is combined with a first power grid voltage relational expression, and the adjusted component current on the d axis is output and input into a current control module; the output value adjusted by the second PID module is combined with a second power grid voltage relational expression to output a current value, the current value is subtracted from a preset value, and the adjusted q-axis component current is output and sent to a current control module; and a signal output by the current control module is sent to the SPWM modulator to obtain a switching signal to control a switching tube of the grid-connected inverter. The power is controlled.

Description

Technical Field

[0001] The invention relates to the field of power regulation and belongs to power control. Background Art

[0002] New energy sources account for a high proportion in new power systems, especially new energy sources such as wind power generation and solar power generation. Therefore, in the process of grid connection, there is a tendency for power output power to fluctuate, resulting in a mismatch between grid power and load, causing power outages. To ensure power stability, reactive power is one of the essential factors for maintaining the normal operation of the power grid. If the reactive power (reactive power factor) is insufficient and too much is required from the grid, the grid will trip, an avalanche effect will occur, and the grid will collapse. Therefore, the regulation of reactive power is particularly important. Reactive power is formed at the moment when the grid or equipment is powered on and started, and is converted from active power. Therefore, only by reasonably adjusting active and reactive power can the power be stable. However, there is a lack of effective regulation of reactive power. Summary of the invention

[0003] The purpose of the present invention is to solve the problem of lack of effective regulation of reactive power in the prior art, and propose a grid-connected power control method for an electric power system.

[0004] A grid-connected power control method for an electric power system, the method comprising the following contents:

[0005] Step 1: Collect the capacitor side output voltage and load side output current of the grid-connected inverter system. The capacitor side output voltage is transformed by a No. 1 Parker converter to obtain the component voltage U on the d-axis. od and the component voltage U on the q axis oq The output current on the load side is transformed by the No. 2 Parker converter to obtain the component current on the d-axis and the component current on the q-axis, and the component voltage U on the d-axis od , component voltage U on the q axis oq The component current on the d-axis and the component current on the q-axis are sent to the power calculation module to obtain the instantaneous active power P of the inverter. s and the instantaneous reactive power Q of the inverter s ;

[0006] Step 2: Reactive reference power and the instantaneous reactive power Q of the inverter s The difference is input to PID module No. 1;

[0007] Active reference power and the instantaneous active power P of the inverter s The difference is input to the second PID module;

[0008] Step 3, the output value adjusted by the No. 1 PID module is combined with the No. 1 grid voltage relationship, and the component current on the d-axis after the adjustment is output and input into the current control module;

[0009] The output value adjusted by the No. 2 PID module is combined with the No. 2 grid voltage relationship to output the current value. The current value is subtracted from the preset value, and the regulated component current on the q axis is sent to the current control module;

[0010] Step 4: The signal output by the current control module is sent to the SPWM modulator to obtain a switching signal to control the switch tube of the grid-connected inverter.

[0011] Preferably, the No. 1 grid voltage relationship V1 is:

[0012]

[0013] Where, L s and L m are adjustment coefficients, V g is the grid voltage.

[0014] Preferably, the No. 1 grid voltage relationship V2 is:

[0015]

[0016] Preferably, the preset coefficient V3 is:

[0017]

[0018] In the formula, w s is the adjustment coefficient.

[0019] The beneficial effects of the present invention are:

[0020] The present invention realizes power decoupling and control, realizes the regulation of reactive power, and makes the power more stable. The present invention uses the grid voltage to establish a relationship, and uses the relationship to regulate reactive power, so that the reactive regulation is more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the grid-connected power control method for the power system. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0024] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0025] Example:

[0026] Combination Figure 1 The present embodiment describes a method for controlling grid-connected power of an electric power system, the method comprising the following contents:

[0027] Step 1: Collect the capacitor side output voltage and load side output current of the grid-connected inverter system. The capacitor side output voltage is transformed by a No. 1 Parker converter to obtain the component voltage U on the d-axis. od and the component voltage U on the q axis oq The output current on the load side is transformed by the No. 2 Parker converter to obtain the component current on the d-axis and the component current on the q-axis, and the component voltage U on the d-axis od , component voltage U on the q axis oq The component current on the d-axis and the component current on the q-axis are sent to the power calculation module to obtain the instantaneous active power P of the inverter. s and the instantaneous reactive power Q of the inverter s ;

[0028] Step 2: Reactive reference power and the instantaneous reactive power Q of the inverter s The difference is input to PID module No. 1;

[0029] Active reference power and the instantaneous active power P of the inverter s The difference is input to the second PID module;

[0030] Step 3, the output value adjusted by the No. 1 PID module is combined with the No. 1 grid voltage relationship, and the component current on the d-axis after the adjustment is output and input into the current control module;

[0031] The output value adjusted by the No. 2 PID module is combined with the No. 2 grid voltage relationship to output the current value. The current value is subtracted from the preset value, and the regulated component current on the q axis is sent to the current control module;

[0032] Step 4: The signal output by the current control module is sent to the SPWM modulator to obtain a switching signal to control the switch tube of the grid-connected inverter.

[0033] Specifically, active power and reactive power are separated and regulated individually to make the power system operate more stably.

[0034] The following introduces the voltage relationship V1 of the No. 1 grid:

[0035]

[0036] Where, L s and L m are adjustment coefficients, V g is the grid voltage.

[0037] Specifically, adopting this relationship makes the regulation smoother.

[0038] The following introduces the voltage relationship V2 of the No. 1 grid:

[0039]

[0040] The preset coefficient V3 is introduced below:

[0041]

[0042] In the formula, w s is the adjustment coefficient.

[0043] Specifically, adopting this relationship makes the regulation smoother.

[0044] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. A grid-connected power control method for an electric power system, characterized in that: The method includes the following: Step 1: Collect the capacitor side output voltage and load side output current of the grid-connected inverter system. The capacitor side output voltage is transformed by a No. 1 Parker converter to obtain the component voltage U on the d-axis. od and the component voltage U on the q axis oq The output current on the load side is transformed by the No. 2 Parker converter to obtain the component current on the d-axis and the component current on the q-axis, and the component voltage U on the d-axis od , component voltage U on the q axis oq The component current on the d-axis and the component current on the q-axis are sent to the power calculation module to obtain the instantaneous active power P of the inverter s and the instantaneous reactive power Q of the inverter s ; Step 2: Reactive reference power and the instantaneous reactive power Q of the inverter s The difference is input to PID module No. 1; Active reference power and the instantaneous active power P of the inverter s The difference is input to the second PID module; Step 3, the output value adjusted by the No. 1 PID module is combined with the No. 1 grid voltage relationship, and the component current on the d-axis after the adjustment is output and input into the current control module; The output value adjusted by the No. 2 PID module is combined with the No. 2 grid voltage relationship to output the current value. The current value is subtracted from the preset value, and the regulated component current on the q axis is sent to the current control module; Step 4: The signal output by the current control module is sent to the SPWM modulator to obtain a switching signal to control the switch tube of the grid-connected inverter.

2. The grid-connected power control method of the electric power system according to claim 1, characterized in that: The voltage relation of the No. 1 grid V1 is: Where, L s and L m are adjustment coefficients, V g is the grid voltage.

3. The grid-connected power control method of the electric power system according to claim 2, characterized in that: The voltage relation of the No. 1 grid V2 is:

4. The grid-connected power control method of the electric power system according to claim 3, characterized in that: Preset coefficient V3: In the formula, w s is the adjustment coefficient.

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