Miniature inverter automatic power control method based on monitoring

Abstract

The invention relates to a micro inverter automatic power control method based on monitoring, and belongs to the technical field of electronics. According to the method, monitoring equipment connected between a micro inverter and a power grid is electrified to collect current and voltage of the power grid; judging whether the actual direction of the current is opposite to the default direction or not; if yes, shutdown is controlled; if not, the output power of each micro inverter is further adjusted according to the relation between the current magnitude and the upper limit calculated value of the current, and therefore automatic control over the output power of the micro inverters is achieved. The control method is realized based on monitoring equipment, and equipment such as an intelligent electric meter does not need to be additionally installed, so that the method disclosed by the invention is more convenient to apply and lower in application cost, and can be widely applied to application scenes for controlling various micro inverters.

Description

Technical Field

[0001] The present invention relates to the field of electronic technology, in particular to the field of circuit control method technology, and specifically refers to a micro inverter automatic power control method based on monitoring. Background Art

[0002] In the field of photovoltaic power generation, micro inverters are used to convert the direct current generated by photovoltaic modules into alternating current suitable for incorporation into the power grid, realizing DC-AC conversion. At the same time, they need to have functions such as overvoltage protection, overcurrent protection, and short-circuit protection to ensure that the system can respond quickly in abnormal situations to avoid equipment damage. At the same time, the working mode of the micro inverter needs to be controlled so that its output power meets the current operating status of the power grid.

[0003] In the prior art, smart meters are usually used to control the working mode of micro inverters. However, the use of smart meters requires additional equipment to be purchased and installed, and requires professional personnel to operate. The use and maintenance costs are very high.

[0004] Therefore, how to provide a more convenient and low-cost micro-inverter automatic power control method has become an urgent problem to be solved in the field. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a micro-inverter automatic power control method which is based on monitoring, more convenient and has lower application cost.

[0006] In order to achieve the above-mentioned purpose, the monitoring device in the present invention is connected to the grid side through a current magnetic ring. At the same time, the monitoring device is connected to a plurality of micro-inverters. The micro-inverter automatic power control method includes:

[0007] The monitoring device is powered on; the monitoring device starts to collect instantaneous current of the power grid through the current magnetic ring, and the monitoring device starts to collect instantaneous voltage;

[0008] The monitoring device saves the current voltage and current direction as default directions;

[0009] The monitoring device cyclically detects whether the actual direction of the current is opposite to the default direction; if so, a shutdown command is sent to control each of the micro-inverters to stop working; if not, an upper limit calculated value Imax of the current is calculated based on the total number of micro-inverters connected;

[0010] The monitoring device adjusts the output power of each micro inverter according to the relationship between the current current and the upper limit calculated value Imax.

[0011] In the monitoring-based automatic power control method for micro-inverters, the monitoring device adjusts the output power of each micro-inverter according to the relationship between the current magnitude and the upper limit calculated value Imax, specifically as follows:

[0012] Determine the control command according to the magnitude of the current i;

[0013] If 0A < i < 0.5A, the monitoring device sends a power reduction command to control the output power of the micro-inverter to decrease slowly;

[0014] If 0.5A ≤ i < Imax, the monitoring device sends a stop command to control the micro-inverter to keep the current output power unchanged;

[0015] If i ≥ Imax, the monitoring device sends an increase command to control the micro-inverter to increase the power.

[0016] In the monitoring-based automatic power control method for micro-inverters, the upper limit calculated value Imax is determined according to the following formula:

[0017] Upper limit calculated value Imax = (single-path jump current + current difference with a 6-second delay) × number of micro-inverter paths + current deviation range + current lower limit.

[0018] In the monitoring-based automatic power control method for micro-inverters, the current difference with a 6-second delay is the current difference with a 6-second delay controlled by hardware; the current deviation range is 0.2A; the lower limit of the current is 0.5A.

[0019] The monitoring-based automatic power control method for micro-inverters of the present invention is adopted. It uses a monitoring device connected between the micro-inverter and the power grid to power on and collect the grid current and voltage; and determines whether the actual direction of the current is opposite to the default direction; if so, controls the shutdown; if not, further adjusts the output power of each micro-inverter according to the relationship between the current magnitude and the upper limit calculated value of the current, thereby realizing the automatic control of the output power of the micro-inverter. This control method is implemented based on the monitoring device, without the need to install additional devices such as smart meters, which makes the application of the method of the present invention more convenient, has a lower application cost, and can be widely applied to various application scenarios of micro-inverter control. Description of the Drawings

[0020] Figure 1 Schematic connection structure diagram of the monitoring device for applying the monitoring-based automatic power control method for micro-inverters of the present invention;

[0021] Figure 2 Flowchart of the monitoring-based automatic power control method for micro-inverters of the present invention;

[0022] Figure 3 This is a schematic flowchart of the actual application of the automatic power control method for a micro-inverter based on monitoring according to the present invention. Specific embodiments

[0023] In order to more clearly understand the technical content of the present invention, the following specific embodiments are given for detailed description.

[0024] In one embodiment, the connection structure of the monitoring device applying the automatic power control method for a micro-inverter based on monitoring is as Figure 1 shown.

[0025] The automatic power control method for a micro-inverter based on monitoring, as Figure 2 shown, includes the following steps:

[0026] Power on the monitoring device; the monitoring device starts to collect the instantaneous current of the power grid through the current magnetic ring, and the monitoring device starts to collect the instantaneous voltage;

[0027] The monitoring device saves the current voltage and current direction as the default direction;

[0028] The monitoring device cyclically detects whether the actual direction of the current is opposite to the default direction; if so, send a shutdown command to control each of the micro-inverters to stop generating power; if not, calculate the upper limit calculated value Imax of the current according to the total number of circuits connected to the detected micro-inverters;

[0029] The monitoring device adjusts the output power of each of the micro-inverters according to the relationship between the current magnitude and the upper limit calculated value Imax.

[0030] In a preferred embodiment, the monitoring device adjusts the output power of each of the micro-inverters according to the relationship between the current magnitude and the upper limit calculated value Imax, specifically:

[0031] Judge the control command according to the magnitude of the current i;

[0032] If 0A < i < 0.5A, the monitoring device sends a power reduction command to control the output power of the micro-inverter to slowly decrease;

[0033] If 0.5A ≤ i < Imax, the monitoring device sends a stop command to control the micro-inverter to keep the current output power unchanged;

[0034] If i ≥ Imax, the monitoring device sends an increase command to control the micro-inverter to increase the power.

[0035] Among them, the upper limit calculated value Imax is determined according to the following formula:

[0036] Upper limit calculated value Imax = (single - path jump current + current difference with 6 - second delay) × number of micro - inverters + current deviation range + current lower limit.

[0037] The current difference with delay is the current difference with a 6 - second delay controlled by hardware; the current deviation range is 0.2 A; the current lower limit is 0.5 A.

[0038] In the practical application of the present invention, the monitoring device is connected to the connection end of the current magnetic ring, and the buckle of the magnetic ring is connected to the user's grid side.

[0039] When the monitoring device is powered on for the first time, it records the existing power grid and current direction as the default state. In the normal working state, the monitoring device simultaneously detects the grid voltage and grid current. When it detects that the direction of the current changes, the monitoring device issues an instruction to control the power generation state of the micro - inverter.

[0040] Specifically, the control process is as Figure 3 shown. When it detects that the current direction is opposite to the default direction, it sends a shutdown command to control the micro - inverter to stop power generation. When the directions are the same, it judges the relationship between the actual magnitude of the current i and the maximum value of the current upper limit. If 0 A < i < 0.5 A, the monitoring device sends a power - reduction instruction to control the micro - inverter to slowly reduce the output power; if 0.5 A ≤ i < Imax, the monitoring device sends a stop instruction to control the micro - inverter to keep the current output power unchanged; if i ≥ Imax, the monitoring device sends an increase instruction to control the micro - inverter to increase the power. Thus, the output power control of the micro - inverter corresponding to different current magnitudes is realized.

[0041] The automatic power control method of the micro - inverter based on monitoring of the present invention is adopted. It uses a monitoring device connected between the micro - inverter and the power grid to collect the grid current and voltage when powered on; and judges whether the actual direction of the current is opposite to the default direction; if so, it controls the shutdown; if not, it further adjusts the output power of each micro - inverter according to the relationship between the current magnitude and the upper limit calculated value of the current, thereby realizing the automatic control of the output power of the micro - inverter. This control method is implemented based on the monitoring device, without the need to install additional devices such as smart meters, so that the application of the method of the present invention is more convenient, the application cost is lower, and it can be widely applied to various control application scenarios of micro - inverters.

[0042] In this specification, the present invention has been described with reference to its specific embodiments. However, it is obvious that various modifications and transformations can still be made without departing from the spirit and scope of the present invention. Therefore, the specification and drawings should be regarded as illustrative rather than restrictive.

Claims

1. A micro-inverter automatic power control method based on monitoring, characterized in that: The monitoring device is connected to the grid side through a current magnetic ring, and the monitoring device is connected to several micro-inverters. The control method includes: Power on the monitoring device; the monitoring device starts to collect the instantaneous current of the grid through the current magnetic ring, and the monitoring device starts to collect the instantaneous voltage; The monitoring device saves the current voltage and current direction as the default direction; The monitoring device cyclically detects whether the actual direction of the current is opposite to the default direction; if so, it sends a shutdown instruction to control each of the micro-inverters to stop generating power; if not, it calculates the upper limit calculated value Imax of the current according to the total number of paths connected to the micro-inverters detected; The monitoring device adjusts the output power of each of the micro-inverters according to the relationship between the current magnitude and the upper limit calculated value Imax.

2. The monitoring-based automatic power control method for micro-inverters according to claim 1, characterized in that: The monitoring device adjusts the output power of each of the micro-inverters according to the relationship between the current magnitude and the upper limit calculated value Imax, specifically: Judge the control instruction according to the magnitude of the current i; If 0A < i < 0.5A, the monitoring device sends a power reduction instruction to control the output power of the micro-inverter to slowly decrease; If 0.5A ≤ i < Imax, the monitoring device sends a stop instruction to control the micro-inverter to keep the current output power unchanged; If i ≥ Imax, the monitoring device sends an increase instruction to control the micro-inverter to increase the power.

3. The monitoring-based automatic power control method for micro-inverters according to claim 1, characterized in that: The upper limit calculated value Imax is determined according to the following formula: Upper limit calculated value Imax = (single-path jump current + delayed current difference) × number of micro-inverters + current deviation range + current lower limit.

4. The monitoring-based automatic power control method for micro-inverters according to claim 3, characterized in that: The delayed current difference is the current difference with a 6-second delay in hardware control; the current deviation range is 0.2A; the current lower limit is 0.5A.

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