An active power servo control device suitable for distributed photovoltaic power plants

Abstract

This invention discloses an active power servo control device suitable for distributed photovoltaic (PV) power plants, belonging to the field of power control technology for distributed PV power plants. The active power servo control device includes: a dual-power supply thermal redundancy circuit, powered by dual AC power sources, ensuring that an interruption in either power source will not cause device failure or restart; a power port protection clamping circuit, used to effectively improve ESD immunity and suppress high-frequency interference; and an active power control module, including two control strategies: remote control mode and local servo control mode. This invention's servo control device, while meeting industrial and commercial load demands, can accurately limit the power generation of "self-consumption with surplus power fed into the grid" type PV power plants, cooperating with regional dispatch to complete power flow regulation tasks.

Description

Technical Field

[0001] This invention relates to an active power servo control device suitable for distributed photovoltaic power plants, belonging to the field of power control technology for distributed photovoltaic power plants. Background Technology

[0002] Currently, distributed photovoltaic (PV) power stations with grid connection voltages above 10kV have participated in grid regulation as a routine regulation resource. However, distributed PV power stations operating on a "self-consumption, surplus power to the grid" model suffer from significant discrepancies between grid connection power data and PV power generation data, affecting the accuracy of their grid regulation participation. For example... Figure 1 As shown, the photovoltaic access acquisition point consists of three parts: a ring main unit (PPC), a user-side metering cabinet, and a photovoltaic access cabinet. Switch 101 is the main incoming switch of the main cabinet, and switch 1021 is the photovoltaic access switch. The PPC in the ring main unit is the connection point between the main power grid and the internal power grid of industrial and commercial users. The power fed into the grid and the power fed out of the grid by users are collected or calculated here. The power consumed by the load of the internal power grid of industrial and commercial users can be calculated by summing the power of the station transformer, outgoing cabinet #1, and outgoing cabinet #2. Currently, the distributed power acquisition and control device installed at the photovoltaic access cabinet can only collect or calculate the actual power generated by the photovoltaic power station, and cannot know the real-time consumption of the load of the user's internal power grid. Therefore, it cannot accurately calculate the real-time function at the PPC. However, regional dispatch often uses the power fed into and out of the grid at the PPC of the user's grid and the main power grid as the reference source for the AGC regulation of the main power grid. Therefore, the general distributed power acquisition and control device cannot meet the needs of "self-consumption and surplus power fed into the grid" type photovoltaic power stations to participate in the AGC regulation of the main power grid.

[0003] On the other hand, when the power grid coordinates and regulates the power flow from a global perspective, requiring photovoltaic power plants to generate and consume their own power without sending power back to the power grid (but they can draw power from the power grid), the photovoltaic power plants need to adjust the power generation capacity of the inverters in the station according to the real-time demand of the user's grid load. The special requirements of this application scenario cannot be met by general distributed power acquisition and control devices. Summary of the Invention

[0004] The purpose of this invention is to overcome the technical defects of the existing technology and solve the problem that the existing general-purpose distributed power acquisition and control devices cannot meet the special needs of the above two application scenarios of the "self-generation and self-consumption, surplus power to the grid" type distributed photovoltaic power station. Compared with the distributed power acquisition and control devices that are currently widely used in distributed photovoltaic power stations, the follow-up control device described in this invention can accurately limit the power generation of the "self-generation and self-consumption, surplus power to the grid" type photovoltaic power station while meeting the industrial and commercial load requirements, and cooperate with regional dispatch to complete the power flow regulation task.

[0005] The present invention specifically adopts the following technical solution: an active power servo control device suitable for distributed photovoltaic power stations, comprising: Dual-power thermal redundancy power supply circuit, which is powered by dual AC power sources, and the interruption of power supply from either power source will not cause device failure or restart. A power port protection clamping circuit is used to effectively improve ESD resistance and suppress high-frequency interference. The active power control module includes two control strategies: remote control mode and local follow-up control mode.

[0006] In a preferred embodiment, when the dual-power supply thermal redundancy power supply circuit is powered, the first AC power supply L1 is given priority; when the first AC power supply L1 loses power, the dual-power supply thermal redundancy power supply circuit automatically switches to the second AC power supply L2; when the first AC power supply L1 and the second AC power supply L2 are powered at the same time, the dual-power supply thermal redundancy power supply circuit automatically switches to be powered by the first AC power supply L1.

[0007] In a preferred embodiment, when L1 is powered, pin 2 of the inverter U3 input is at a high level, and pin 4 of the inverter U3 output is at a low level. At this time, optocoupler U1 is turned on, optocoupler U4 is turned off, and the dual-power switching circuit automatically uses AC power from L1. Conversely, when L1 is de-powered and L2 is powered, since pin 2 of the inverter U3 is at a low level and pin 4 of the inverter U3 is at a high level, optocoupler U1 is turned off, optocoupler U4 is turned on, and the dual-power switching circuit automatically uses AC power from L2. When both L1 and L2 are powered, the dual-power switching circuit automatically switches to AC power from L1.

[0008] In a preferred embodiment, the power port protection clamping circuit includes: a transient voltage suppressor Q1 and a resistor R1 connected in series and placed between the power rails; the center point of the transient voltage suppressor Q1 and the resistor R1 network is connected to an inverter, the output terminal of the inverter is connected to the base of a transistor Q2, the emitter of the transistor Q2 is connected to GND through a resistor R2, the power supply is connected to the collector of the transistor Q2, the transient voltage suppressor Q1, and the inverter, and the resistor R1 is connected to GND.

[0009] As a preferred embodiment, the remote control mode of the active power control module includes: the follow-up control device uses an intelligent allocation strategy with similar adjustment margin and power proportionality to decompose the active power target value issued by the regional dispatch and then issues it to each online inverter in the photovoltaic station for execution, so as to ensure the adjustment accuracy of the photovoltaic power station and the optimal operating mode of the photovoltaic inverter, and meet the AGC control target of the regional dispatch.

[0010] As a preferred embodiment, the local follow-up control mode of the active power control module includes: when the power grid regulates the flow and requires the "self-consumption with surplus power fed into the grid" type photovoltaic power station to switch to the local follow-up control mode, the regional dispatch instruction follow-up control device switches to the local follow-up control mode. At this time, the follow-up control device controls the photovoltaic power station to generate power moderately, only to meet the normal operation of industrial and commercial loads, without transmitting a large amount of power to the power grid; when the irradiance is insufficient, even if the photovoltaic power station is in a free power generation state, it still cannot meet the normal operation of industrial and commercial loads, the load obtains active power from the power grid through the point of common coupling (PPC).

[0011] As a preferred embodiment, the local follow-up control mode specifically includes the following steps: Step SS1: The ground control sends a remote control command to the servo control device, commanding the servo control device to enter the local servo control mode; Step SS2: The follow-up control device adjusts the power generation of the photovoltaic power station in real time according to the real-time active power required by industrial and commercial production: Under the premise of meeting the power required for the factory's own production, the power transmitted from the user grid to the main grid is basically 0; During this process, the follow-up control device needs to collect the power generation of the photovoltaic inverter, the power consumption of the user load, and the power flow of the PPC at the grid connection point in real time. Step SS3: The follow-up control device reports the control status to the local dispatching station in real time: (1) The current control mode of the follow-up control device is the local follow-up control mode; (2) The current power generation status of all inverters in the photovoltaic power station; (3) The power consumption status of user load; (4) The power flow status of PPC at the grid connection point; Step SS4: When the local dispatch master station needs to directly control the power generation of the photovoltaic power station, the local dispatch sends a remote control command to the follow-up control device, ordering the follow-up control device to immediately switch to the "remote control" mode. After receiving the command, the follow-up control device immediately switches from the "local follow-up control" mode to the "remote control" mode.

[0012] The beneficial effects achieved by this invention are as follows: First, the active power servo control device proposed in this invention, applicable to distributed photovoltaic power stations, is mainly used in "self-consumption with surplus power fed into the grid" type industrial and commercial photovoltaic power stations. When the power grid regulates the flow and requires the distributed photovoltaic power station to "consume its own power" and no longer supply large amounts of power to the grid through the point of common coupling (PPC), the regional dispatch can more accurately and effectively control the active power of the power station through this active power servo control device. Second, the active power servo control device of this invention (hereinafter referred to as the servo control device) includes functions such as grid connection point electrical quantity acquisition and calculation, inverter information collection and control, electrical energy and micro-meteorological information forwarding, active power control, network security monitoring, wireless communication, and vertical encryption, among which the active power control function module is the core. Third, the active power control function module of this invention includes two control strategies, one of which is a remote control mode, and the servo control device... The system employs intelligent allocation strategies such as similar adjustment margin and proportional power distribution. The active power target value issued by the regional dispatch center is decomposed and distributed to each online inverter within the photovoltaic power station for execution, ensuring the adjustment accuracy of the photovoltaic power station and the optimal operating mode of the photovoltaic inverters. Secondly, based on the regional dispatch instructions, the servo control device switches to local servo control mode. Fourthly, at this time, the servo control device controls the photovoltaic power station to generate power moderately, only meeting the normal operation of industrial and commercial loads, without transmitting large amounts of power to the main grid. When the irradiance is insufficient, even when the photovoltaic power station is in a free-generating state, it still cannot meet the normal operation of industrial and commercial loads. The load obtains active power from the main grid through the point of common coupling (PPC). The network security monitoring module is responsible for collecting, storing, and processing the network security log information of the distributed photovoltaic power station. The servo control device transmits power station operation information to the regional dispatch center via a private wireless network and xPON fiber optic network, and receives and executes regional dispatch instructions. The servo control device is powered by two power sources, and the interruption of power supply to either power source will not cause the device to malfunction or restart. The protection and clamping circuits of the power port of the servo control device can effectively improve the anti-ESD level and suppress high-frequency interference. Fifth, compared with the distributed power acquisition and control devices that are currently widely used in distributed photovoltaic power stations, the servo control device described in this invention can accurately limit the power generation of "self-consumption and surplus power grid connection" type photovoltaic power stations while meeting the needs of industrial and commercial loads, and cooperate with regional dispatch to complete the power flow regulation task. Attached Figure Description

[0013] Figure 1 This is a typical electrical wiring diagram for a distributed photovoltaic power station that is "self-generated and self-consumed, with surplus electricity fed into the grid".

[0014] Figure 2 This is a schematic diagram of the dual-channel AC power supply thermal redundancy power supply circuit of the present invention.

[0015] Figure 3 This is a schematic diagram of the power port protection clamping circuit of the present invention.

[0016] Figure 4 This is a block diagram illustrating the active power control principle of an active power servo control device applicable to distributed photovoltaic power stations according to the present invention. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0018] Example 1: As Figure 2 As shown, this invention proposes an active power servo control device suitable for distributed photovoltaic power stations, comprising: Dual-power thermal redundancy power supply circuit, which is powered by dual AC power sources, and the interruption of power supply from either power source will not cause device failure or restart. A power port protection clamping circuit is used to effectively improve ESD resistance and suppress high-frequency interference. The active power control module includes two control strategies: remote control mode and local follow-up control mode.

[0019] Optional, such as Figure 2 As shown, when the dual-power supply thermal redundancy power supply circuit is powered, the first AC power supply L1 is given priority; when the first AC power supply L1 loses power, the dual-power supply thermal redundancy power supply circuit automatically switches to the second AC power supply L2; when the first AC power supply L1 and the second AC power supply L2 are powered at the same time, the dual-power supply thermal redundancy power supply circuit automatically switches to the first AC power supply L1 for power supply. When L1 is powered, pin 2 of the inverter U3 input is high and pin 4 of the inverter U3 output is low. At this time, optocoupler U1 is turned on and optocoupler U4 is turned off, and the dual-power switching circuit automatically uses AC power from L1. Conversely, when L1 is de-powered and L2 is powered, pin 2 of the inverter U3 is low and pin 4 of the inverter U3 is high. At this time, optocoupler U1 is turned off and optocoupler U4 is turned on, and the dual-power switching circuit automatically uses AC power from L2. When both L1 and L2 are powered, the dual-power switching circuit automatically switches to AC power from L1.

[0020] like Figure 2As shown, resistor R1, capacitor C1, diode D2, diode D3, and other components constitute the first AC input power supply L1, which supplies power to inverter U3. Resistor R5, capacitor C3, diode D5, diode D6, and other components constitute the second AC input power supply L2, which supplies power to inverter U3. Zener diode D4, filter capacitor C2, and other components maintain the supply voltage of inverter U3 at approximately 5V. The circuit formed by components R1, C1, D1, D7, C5, and R6 serves as the input of inverter U3. Zener diode D7 and capacitor C5 protect pin 2 of U3, which serves as the input. When L1 is energized, the voltage level on pin 2 of U3 is approximately 4.3V; when L1 is de-energized, the voltage level on pin 2 of U3 is 0V.

[0021] The inverter U3 is model SN74AHC1G14DBVR, with an operating voltage of 2.5-5.5V, used for selecting the AC power input channel. Pin 5 of inverter U3 is connected to pin 1 of optocoupler U1, pin 3 of inverter U3 is connected to pin 2 of optocoupler U4, and pin 4 of inverter U3 is connected to pin 2 of optocoupler U1 and pin 1 of optocoupler U4 via resistor R3. Pin 4 of optocoupler U1 is connected to triac U2, and pin 4 of optocoupler U4 is connected to triac U5. Optocoupler U1 is model MOC3061, used for isolation between the control circuit and the power output circuit. The triac U2 is model BTA24-800B, and its conduction is determined by its control electrode G. The protective devices, varistors RP1, RP2, and RP3, are model 20K681. R1, R2, R3, R4, R5, and R6 are all resistors; D1, D2, D3, D5, and D6 are general-purpose diodes; D4 and D7 are Zener diodes; C1 and C3 are filter capacitors, both 0.33uF / 600V; C2 is an electrolytic capacitor, rated at 1000uF / 10V, used for filtering and bypassing; C5 is rated at 1uF / 10V, also used for filtering and bypassing. C4 is rated at 100nF / 10V and, together with resistor R3, forms an RC filter circuit to suppress differential-mode interference; C2 is a filter electrolytic capacitor used for filtering after rectification; C4 and C5 are output filter capacitors, filtering out high-frequency ripple and improving output stability.

[0022] The optocoupler U4 is model MOC3061, used for isolation between the control circuit and the power output circuit; the bidirectional thyristor U5 is model BTA24-800B, and its conduction capability is determined by its control electrode G.

[0023] Optional, such as Figure 3As shown, the power port protection clamping circuit includes: a transient voltage suppressor Q1 and a resistor R1 connected in series and placed between the power rails; the center point of the transient voltage suppressor Q1 and resistor R1 network is connected to an inverter; the output terminal of the inverter is connected to the base of transistor Q2; the emitter of transistor Q2 is connected to GND through resistor R2; the power supply is connected to the collector of transistor Q2, the transient voltage suppressor Q1, and the inverter; and resistor R1 is connected to GND. Q1 is an SMBJ5A, the inverter includes U1A and U1B connected in series (U1A and U1B are model 74HC2G14GV), and Q2 is a MJD3055. The center point of the resistor R1 and transient voltage suppressor Q1 network is connected to pin 1 of U1A. Pin 5 of U1A is connected to the 5V power supply. Pin 2 of U1A is connected to CND. Pin 6 of U1A is connected to pin 3 of U1B. Pin 4 of U1B is connected to the base of transistor Q2.

[0024] Optionally, the remote control mode of the active power control module includes: the follow-up control device adopts an intelligent allocation strategy with similar adjustment margin and power proportionality to decompose the active power target value issued by the regional dispatch and then issue it to each online inverter in the photovoltaic station for execution, so as to ensure the adjustment accuracy of the photovoltaic power station and the optimal operating mode of the photovoltaic inverter, and meet the AGC control target of the regional dispatch.

[0025] Optionally, the local follow-up control mode of the active power control module includes: when the power grid adjusts the power flow and requires the "self-consumption with surplus power fed into the grid" type photovoltaic power station to switch to the local follow-up control mode, the regional dispatch instruction follow-up control device switches to the local follow-up control mode. At this time, the follow-up control device controls the photovoltaic power station to generate power moderately, only to meet the normal operation of industrial and commercial loads, without transmitting a large amount of power to the power grid; when the irradiance is insufficient, even if the photovoltaic power station is in a free power generation state, it still cannot meet the normal operation of industrial and commercial loads, the load obtains active power from the power grid through the point of common coupling (PPC).

[0026] Optionally, the local follow-up control mode specifically includes the following steps: Step SS1: The ground control sends a remote control command to the servo control device, commanding the servo control device to enter the local servo control mode; Step SS2: The follow-up control device adjusts the power generation of the photovoltaic power station in real time according to the real-time active power required by industrial and commercial production: Under the premise of meeting the power required for the factory's own production, the power transmitted from the user grid to the main grid is basically 0; During this process, the follow-up control device needs to collect the power generation of the photovoltaic inverter, the power consumption of the user load, and the power flow of the PPC at the grid connection point in real time. Step SS3: The follow-up control device reports the control status to the local dispatching station in real time: (1) The current control mode of the follow-up control device is the local follow-up control mode; (2) The current power generation status of all inverters in the photovoltaic power station; (3) The power consumption status of user load; (4) The power flow status of PPC at the grid connection point; Step SS4: When the local dispatch master station needs to directly control the power generation of the photovoltaic power station, the local dispatch sends a remote control command to the follow-up control device, ordering the follow-up control device to immediately switch to the "remote control" mode. After receiving the command, the follow-up control device immediately switches from the "local follow-up control" mode to the "remote control" mode.

[0027] As shown in Figure 4, the "self-generation and self-consumption, surplus power to the grid" type photovoltaic power station of the present invention is connected to the grid connection point at one end and to the user load at the output end. At the same time, the output end provides balance feedback K1 to the grid connection point, and the user load provides balance feedback K2 to the grid connection point. The follow-up control device collects and analyzes the power grid connection and disconnection data, user load data, and photovoltaic inverter power generation data. It adopts the AGC intelligent allocation strategy to decompose the active power target value issued by the regional dispatch and then controls the inverter, which is the actuator, to adjust.

[0028] The innovation of this invention lies in its novel active power servo control device for distributed photovoltaic (PV) power plants, primarily applied to "self-consumption with surplus power fed into the grid" industrial and commercial PV power plants. When the main grid regulates power flow, requiring distributed PV power plants to "consume their own power" and no longer supply large amounts of electricity to the main grid through the point of common coupling (PPC), the regional dispatch center can more accurately and effectively control the active power of the power plant through this active power servo control device. The novel active power servo control device (hereinafter referred to as the servo control device) includes functions such as grid connection point electrical quantity acquisition and calculation, inverter information collection and control, electrical energy and micro-meteorological information forwarding, active power control, network security monitoring, wireless communication, and vertical encryption. The active power control module is the core component. This module includes two control strategies, one of which is a remote control mode. The servo control device employs intelligent allocation strategies such as similar adjustment margin and proportional power distribution. It decomposes the active power target value issued by the regional dispatch center and distributes it to each online inverter within the photovoltaic power station for execution, ensuring the adjustment accuracy of the photovoltaic power station and the optimal operating mode of the photovoltaic inverters. Secondly, based on regional dispatch instructions, the servo control device switches to local servo control mode. In this mode, the servo control device controls the photovoltaic power station to generate power moderately, only meeting the normal operation of industrial and commercial loads, without transmitting large amounts of power to the main grid. When the irradiance is insufficient, even when the photovoltaic power station is in a free-generating state, it still cannot meet the normal operation of industrial and commercial loads, and the load obtains active power from the main grid through the point of common coupling (PPC). The network security monitoring module is responsible for the collection, storage, and processing of network security log information for the distributed photovoltaic power station. The servo control device transmits power station operation information to the regional dispatch master station through a private wireless network and an xPON fiber optic network, and receives and executes regional dispatch instructions. The servo control device is powered by two power sources, and the interruption of power supply to either source will not cause the device to malfunction or restart. The protection and clamping circuits at the power ports of the servo control device can effectively improve ESD resistance and suppress high-frequency interference. Compared with the distributed power acquisition and control devices widely used in distributed photovoltaic power plants, the servo control device described in this invention can accurately limit the power generation of "self-consumption with surplus power fed into the grid" type photovoltaic power plants while meeting the load requirements of industrial and commercial applications, and cooperate with regional dispatch to complete power flow regulation tasks.

[0029] The technical parameters of an active power servo control device suitable for distributed photovoltaic power stations in this embodiment are shown in Table 1: Table 1 Technical Parameters

[0030] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An active power servo control device suitable for distributed photovoltaic power stations, characterized in that, include: Dual-power thermal redundancy power supply circuit, which is powered by dual AC power sources, and the interruption of power supply from either power source will not cause device failure or restart. A power port protection clamping circuit is used to effectively improve ESD resistance and suppress high-frequency interference. An active power control module, which includes two control strategies: a remote control mode and a local follow-up control mode. When the dual-power supply thermal redundancy power supply circuit is powered, the first AC power supply L1 is given priority; when the first AC power supply L1 loses power, the dual-power supply thermal redundancy power supply circuit automatically switches to the second AC power supply L2; when the first AC power supply L1 and the second AC power supply L2 are powered at the same time, the dual-power supply thermal redundancy power supply circuit automatically switches to be powered by the first AC power supply L1. When L1 is energized, pin 2 of inverter U3 is high, and pin 4 of inverter U3 is low. At this time, optocoupler U1 is on, optocoupler U4 is off, and the dual-power switching circuit automatically uses AC power from L1. Conversely, when L1 is de-energized and L2 is energized, pin 2 of inverter U3 is low, and pin 4 of inverter U3 is high. At this time, optocoupler U1 is off, optocoupler U4 is on, and the dual-power switching circuit automatically uses AC power from L2. When both L1 and L2 are energized simultaneously, the dual-power switching circuit automatically switches to AC power from L1. An active power servo control device suitable for distributed photovoltaic power stations is characterized by comprising: Dual-power thermal redundancy power supply circuit, which is powered by dual AC power sources, and the interruption of power supply from either power source will not cause device failure or restart. A power port protection clamping circuit is used to effectively improve ESD resistance and suppress high-frequency interference. An active power control module, which includes two control strategies: a remote control mode and a local follow-up control mode. When the dual-power supply thermal redundancy power supply circuit is powered, the first AC power supply L1 is given priority; when the first AC power supply L1 loses power, the dual-power supply thermal redundancy power supply circuit automatically switches to the second AC power supply L2; when the first AC power supply L1 and the second AC power supply L2 are powered at the same time, the dual-power supply thermal redundancy power supply circuit automatically switches to be powered by the first AC power supply L1. When L1 is powered, pin 2 of inverter U3 is high and pin 4 of inverter U3 is low. At this time, optocoupler U1 is turned on and optocoupler U4 is turned off, and the dual-power switching circuit automatically uses AC power from L1. Conversely, when L1 is de-powered and L2 is powered, pin 2 of inverter U3 is low and pin 4 of inverter U3 is high. At this time, optocoupler U1 is turned off and optocoupler U4 is turned on, and the dual-power switching circuit automatically uses AC power from L2. When both L1 and L2 are powered, the dual-power switching circuit automatically switches to AC power from L1.

2. The active power servo control device for distributed photovoltaic power stations according to claim 1, characterized in that, The power port protection clamping circuit includes: a transient voltage suppressor Q1 and a resistor R1 connected in series and placed between the power rails; the center point of the transient voltage suppressor Q1 and resistor R1 network is connected to an inverter, the output terminal of the inverter is connected to the base of transistor Q2, the emitter of transistor Q2 is connected to GND through resistor R2, the power supply is connected to the collector of transistor Q2, the transient voltage suppressor Q1, and the inverter, and the resistor R1 is connected to GND.

3. The active power servo control device for distributed photovoltaic power stations according to claim 1, characterized in that, The remote control mode of the active power control module includes: the follow-up control device adopts an intelligent allocation strategy with similar adjustment margin and power proportionality to decompose the active power target value issued by the regional dispatch and then issue it to each online inverter in the photovoltaic station for execution, so as to ensure the adjustment accuracy of the photovoltaic power station and the optimal operating mode of the photovoltaic inverter, and meet the AGC control target of the regional dispatch.

4. The active power servo control device for distributed photovoltaic power stations according to claim 1, characterized in that, The local follow-up control mode of the active power control module includes: when the power grid adjusts the flow and requires the "self-consumption with surplus power fed into the grid" type photovoltaic power station to switch to the local follow-up control mode, the regional dispatch instruction follow-up control device switches to the local follow-up control mode. At this time, the follow-up control device controls the photovoltaic power station to generate power moderately, only to meet the normal operation of industrial and commercial loads, without transmitting a large amount of power to the power grid; when the irradiance is insufficient, even if the photovoltaic power station is in a free power generation state, it still cannot meet the normal operation of industrial and commercial loads, the load obtains active power from the power grid through the point of common coupling (PPC).

5. The active power servo control device for distributed photovoltaic power stations according to claim 4, characterized in that, The local follow-up control mode specifically includes the following steps: Step SS1: The ground control sends a remote control command to the servo control device, commanding the servo control device to enter the local servo control mode; Step SS2: The follow-up control device adjusts the power generation of the photovoltaic power station in real time according to the real-time active power required by industrial and commercial production: Under the premise of meeting the power required for the factory's own production, the power transmitted from the user grid to the main grid is basically 0; During this process, the follow-up control device needs to collect the power generation of the photovoltaic inverter, the power consumption of the user load, and the power flow of the PPC at the grid connection point in real time. Step SS3: The follow-up control device reports the control status to the local dispatching station in real time: (1) The current control mode of the follow-up control device is the local follow-up control mode; (2) The current power generation status of all inverters in the photovoltaic power station; (3) The power consumption status of user load; (4) The power flow status of PPC at the grid connection point; Step SS4: When the local dispatch master station needs to directly control the power generation of the photovoltaic power station, the local dispatch sends a remote control command to the follow-up control device, ordering the follow-up control device to immediately switch to the "remote control" mode. After receiving the command, the follow-up control device immediately switches from the "local follow-up control" mode to the "remote control" mode.

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