Coordinated control system and method for phase modifier and network building inverter

Abstract

The invention provides a phase modifier and network inverter coordination control system and method, the system comprises a network inverter, a phase modifier, an RMS module and a low-pass filter, the network inverter comprises a network inverter reactive power regulation system, the phase modifier comprises a phase modifier excitation system, and the network inverter and the phase modifier are connected in parallel and then are connected with a power system; the RMS module outputs a voltage deviation signal to the low-pass filter by combining the received voltage signal with a voltage standard value; a low-pass filter receives and filters the voltage deviation signal, and outputs a high-frequency deviation signal and a low-frequency deviation signal to a phase modifier excitation system and an inverter reactive power regulation system respectively; when a transient process occurs in the power system, the phase modifier excitation system responds to the high-frequency deviation signal to maintain the voltage stable; and after the power system enters a steady state, the grid-forming inverter reactive power regulation system responds to the low-frequency deviation signal to maintain the voltage stable. Therefore, the frequency division response of the network building inverter and the phase modifier can be realized, and the stability of the power grid is maintained.

Description

Technical Field

[0001] The present disclosure relates to the technical field of power grid control, and in particular to a coordinated control system and method for phase regulators and grid-connected inverters. Background Art

[0002] The new power system has the "double high" characteristics of a high proportion of renewable energy and a high proportion of power electronic equipment access. Although the inverter access system with multiple control logics can simulate some characteristics of traditional devices to a certain extent, it has defects in overcurrent capacity, response time, harmonic suppression, etc. due to the limitations of its own power electronic devices. In addition, the normal operation of contemporary power electronic power supplies depends on a good grid strength, and the access of new energy has caused many weak grid problems.

[0003] In the existing specific projects of dynamic compensation devices, each device is designed only according to its own control objectives. Each device is often considered only from its own perspective, with limited understanding of regulations and specifications, and lacks a systematic understanding of the global strategy of dynamic compensation devices. Different devices have different characteristics in transient and steady-state conditions, and should be coordinated and controlled according to the characteristics of the device itself. Therefore, there is still a lack of a method for coordinated control of phase-shifting and grid-forming inverters in this field to obtain a coordinated operation method that takes into account grid safety, economy, and equipment reliability. Summary of the invention

[0004] The present disclosure provides a phase modulator and a grid-connected inverter coordinated control system and method. According to a first aspect of the present disclosure, a phase modulator and a grid-connected inverter coordinated control system is provided, the system comprising: A grid-connected inverter, a phase modulator, an RMS module and a low-pass filter, wherein the grid-connected inverter comprises a grid-connected inverter reactive power regulation system and a grid-connected inverter active power regulation system, the phase modulator comprises a phase modulator excitation system, and the grid-connected inverter and the phase modulator are connected in parallel to the power system; The RMS module is used to receive a voltage signal, and output a voltage deviation signal to a low-pass filter according to the voltage signal and a voltage standard value; The low-pass filter receives the voltage deviation signal and filters the voltage deviation signal, outputs a high-frequency deviation signal to the phase-shifting excitation system, and outputs a low-frequency deviation signal to the inverter reactive power regulation system; When a transient process occurs in the power system, the phase modulator excitation system responds to the high-frequency deviation signal to maintain voltage stability; When the power system enters a steady state, the inverter reactive power regulation system responds to the low-frequency deviation signal to maintain voltage stability.

[0005] According to the aspects described above and any possible implementation methods, an implementation method is further provided, wherein the grid-connected inverter active power regulation system responds to a frequency deviation signal and adjusts its active power output according to a preset active power-frequency droop characteristic.

[0006] According to the above aspects and any possible implementation, an implementation is further provided, wherein the phase modulator excitation system comprises: Lead-lag compensator, used to perform phase correction on input voltage deviation signal to improve the dynamic response performance of the system; A main regulator, connected to the lead-lag compensator, for calculating and generating a control instruction according to an input voltage deviation signal; A proportional saturator connected to the main regulator, used to limit the output range of the control command to prevent excessive excitation current; an exciter, connected to the proportional saturator, for generating an excitation current according to the control instruction and providing the excitation current to the excitation winding of the phase regulator; The damping unit is connected to the exciter and is used to suppress the oscillation of the system and improve the stability.

[0007] According to the above aspects and any possible implementation, an implementation is further provided, wherein the grid-connected inverter reactive power regulation system comprises: The machine-end voltage controller is used to output a voltage adjustment instruction according to the input voltage deviation signal; A reactive power controller is used to output a reactive power regulation instruction according to the deviation between the input reactive power reference value and the actual reactive power output; The no-load potential regulating unit is used to adjust the internal potential of the inverter according to the no-load potential characteristics and actual operating status of the inverter to optimize the reactive power output.

[0008] According to the above aspects and any possible implementation, an implementation is further provided, when a transient process occurs in the power system, the phase regulator changes the excitation current in response to the high-frequency deviation signal, and increases or decreases the reactive power output to maintain voltage stability; When the power system enters a steady state, the grid-connected inverter responds to the low-frequency deviation signal, adjusts the excitation electromotive force of the synchronous motor to adjust the output reactive power, gradually replaces the reactive power output of the phase regulator, and maintains voltage stability.

[0009] According to a second aspect of the present disclosure, a method for coordinated control of a phase modulator and a grid-connected inverter is provided. Based on any one of the above-described coordinated control systems for a phase modulator and a grid-connected inverter, the method comprises: Acquire a voltage signal in the power line, and convert the voltage signal into a voltage effective value through an RMS module; Determining a voltage deviation signal according to the voltage effective value and a preset voltage standard value; The voltage deviation signal is filtered by the low-pass filter to obtain a low-frequency deviation signal and a high-frequency deviation signal; The high-frequency deviation signal is input into the phase modulator excitation system, and the low-frequency deviation signal is input into the inverter reactive power regulation system to achieve the frequency division response of the grid-forming inverter and the phase modulator.

[0010] According to the above aspects and any possible implementation manner, an implementation manner is further provided, wherein converting the voltage signal into a voltage effective value by an RMS module comprises: Acquiring time series data of the voltage signal; Performing a square operation on the time series data through an RMS module, and calculating the average value of the data obtained after the square operation within a preset period; A square root operation is performed on the average value to obtain a voltage effective value.

[0011] According to the above aspects and any possible implementation, an implementation is further provided, wherein the high-frequency deviation signal is input into the phase modulator excitation system, and the low-frequency deviation signal is input into the inverter reactive power regulation system to achieve the frequency division response of the grid-connected inverter and the phase modulator, including: When a transient process occurs in the power system, the phase regulator excitation system responds to the high-frequency deviation signal and outputs an excitation current adjustment instruction to increase or decrease the reactive power output of the phase regulator and stabilize the voltage; When the power system enters a steady state, the reactive power regulation system of the grid-connected inverter responds to the low-frequency deviation signal, outputs reactive power regulation instructions by adjusting the excitation electromotive force of the synchronous motor, gradually replaces the reactive power output of the phase regulator, and maintains voltage stability.

[0012] According to the above aspects and any possible implementation manner, an implementation manner is further provided, wherein the method further includes: When a transient process occurs in the power system, the reactive power regulation system of the grid-connected inverter responds to the low-frequency deviation signal to avoid overload; When the power system enters a steady state, the phase regulator excitation system responds to the high-frequency deviation signal and restores the initial state to ensure that there is sufficient reactive power regulation margin when the system changes next time.

[0013] According to the above aspects and any possible implementation, an implementation is further provided, wherein the grid-connected inverter reactive power regulation system responds to the low-frequency deviation signal, outputs a reactive power regulation instruction by adjusting the excitation electromotive force of the synchronous motor, and gradually replaces the reactive power output of the phase regulator, including: Set the minimum reactive power output of the condenser based on the current stability of the system; Gradually reduce reactive power output through the excitation controller of the phase regulator; The grid inverter adjusts the excitation electromotive force of the synchronous motor to output reactive power regulation instructions, gradually increases the reactive power output, and compensates for the reduced reactive power of the phase regulator until the reactive power output of the phase regulator reaches the minimum value.

[0014] Compared with the prior art, the present invention achieves the following beneficial effects: The present invention provides a system and method for coordinated control of a phase modulator and a grid-type inverter. According to the different characteristics of the phase modulator and the grid-type inverter, the phase modulator provides reactive power support in the transient process, and after the steady state, the grid-type inverter replaces the reactive power of the phase modulator to support the system. The frequency division response of the phase modulator and the grid-type inverter is realized, which not only realizes the protection of the power electronic device, but also realizes the stable support of the power system.

[0015] It should be understood that the contents described in the summary of the invention are not intended to limit the key or important features of the embodiments of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. The accompanying drawings are used to better understand the present solution and do not constitute a limitation of the present disclosure. In the accompanying drawings, the same or similar reference numerals represent the same or similar elements, among which: Figure 1 A schematic diagram of coordinated control of a phase regulator and a grid-connected inverter according to an embodiment of the present disclosure is shown; Figure 2 A schematic diagram showing the connection of various devices according to an embodiment of the present disclosure is shown; Figure 3 A flow chart of a method for coordinated control of a phase modulator and a grid-connected inverter according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0018] In addition, the term "and / or" in this article is only a description of the association relationship between the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0019] The present disclosure provides a coordinated control system and method for a phase-shifting and grid-connected inverter, the system comprising: a grid-connected inverter, a phase-shifting, an RMS module and a low-pass filter, the grid-connected inverter comprising a grid-connected inverter reactive power regulation system, the phase-shifting comprising a phase-shifting excitation system, the grid-connected inverter and the phase-shifting being connected in parallel to the power system; the RMS module outputs a voltage deviation signal to the low-pass filter in combination with a voltage standard value based on the received voltage signal; the low-pass filter receives the voltage deviation signal and filters it, and outputs a high-frequency deviation signal and a low-frequency deviation signal to the phase-shifting excitation system and the inverter reactive power regulation system respectively; when a transient process occurs in the power system, the phase-shifting excitation system responds to the high-frequency deviation signal to maintain voltage stability; when the power system enters a steady state, the reactive power regulation system of the grid-connected inverter responds to the low-frequency deviation signal to maintain voltage stability. In this way, the frequency division response of the grid-connected inverter and the phase-shifting can be achieved to maintain the stability of the power grid.

[0020] A specific embodiment of a phase modulator and grid-connected inverter coordinated control system provided by the present disclosure is described below in conjunction with the accompanying drawings.

[0021] like Figure 1-Figure 2 As shown, an embodiment of the present disclosure provides a schematic diagram of a coordinated control system of a phase regulator and a grid-connected inverter, the system comprising: A grid-connected inverter, a phase modulator, an RMS module and a low-pass filter, wherein the grid-connected inverter comprises a grid-connected inverter reactive power regulation system and a grid-connected inverter active power regulation system, the phase modulator comprises a phase modulator excitation system, and the grid-connected inverter and the phase modulator are connected in parallel to the power system; The RMS module is used to receive a voltage signal, and output a voltage deviation signal to a low-pass filter according to the voltage signal and a voltage standard value; The low-pass filter receives the voltage deviation signal and filters the voltage deviation signal, outputs a high-frequency deviation signal to the phase-shifting excitation system, and outputs a low-frequency deviation signal to the inverter reactive power regulation system; When a transient process occurs in the power system, the phase modulator excitation system responds to the high-frequency deviation signal to maintain voltage stability; When the power system enters a steady state, the inverter reactive power regulation system responds to the low-frequency deviation signal to maintain voltage stability.

[0022] As a preferred embodiment, a grid-connected inverter is a device that converts direct current into alternating current, so that the generated electricity can be fed into the grid or supplied to households and industries. Its working principle can be divided into the following steps: a. DC input: The grid-connected inverter receives current from a DC power source, such as a solar array or battery.

[0023] b. Converting DC to AC: The inverter has a built-in inverter circuit, which usually includes switching devices (such as transistors or IGBTs) and control circuits. These switching elements switch quickly according to certain control signals to form a pulse width modulation (PWM) signal to generate AC power of the required frequency and amplitude.

[0024] c. Filtering: The generated AC power is usually a square wave or pulse waveform, so it needs to be smoothed by a filter and converted into a sinusoidal waveform to meet the needs of the power grid or load.

[0025] d. Synchronization and grid connection: The inverter also needs to be synchronized with the grid to ensure that the output AC frequency, phase and voltage are consistent with the grid. During the grid connection process, the inverter will continuously monitor the grid status to ensure that the power is safely and stably transmitted to the grid.

[0026] e. Protection function: The grid-connected inverter also has a variety of protection functions, such as overload protection, short circuit protection, overvoltage protection, etc., to ensure the safety of equipment and power grid.

[0027] As a preferred embodiment, the phase regulator is a power electronic device that can adjust the current phase during the operation of the power system. It is essentially a no-load synchronous motor with zero mechanical power input, and the terminal voltage is maintained stable through excitation control. It is mainly used to optimize the power factor, reduce reactive power, and improve the transmission capacity and power quality of the system. The phase regulator can generate or absorb reactive power. In the power grid, when the load demand exceeds the active power provided by the power supply, it will cause the current phase to lag (such as inductive load), and the phase regulator can compensate by providing reactive power. On the contrary, when the power grid needs to reduce reactive power, the phase regulator can absorb excess reactive power and improve the power factor.

[0028] As a preferred embodiment, 1. Inverter active power control The first branch in the figure is a control block diagram of the active power control system of the grid-building inverter. The present disclosure selects the virtual synchronous machine technology as the control mode of the grid-building inverter. In order to simulate the frequency modulation characteristics of the synchronous generator, a speed regulator is applied in the VSG control. The speed regulator is the droop characteristic between the active power and the frequency, as shown in the formula:

[0029] Where: is the reference active power; is the active power-frequency droop coefficient. In order to change the rigid external characteristics of the inverter, virtual inertia and damping are further added, that is, the rotor motion equation of the synchronous generator is simulated, as shown in the formula:

[0030] Where: J is the moment of inertia; D is the damping torque; Pm represents the mechanical power of the synchronous generator; Pe represents the electromagnetic power; ω and ω0 represent the reference angular velocity of VSG control and the grid synchronization angular velocity, respectively.

[0031] Substituting formula (2) into formula (1) yields:

[0032] Where: kp is equivalent to the adjustment ratio of the synchronous motor speed regulator, which indicates the change in mechanical torque caused by a certain frequency offset; D indicates the damping coefficient of the system, which can ensure that the frequency changes within a reasonable range during the adjustment process; the inertia time constant J indicates that VSG has virtual mechanical inertia, which can control the inertia size during the entire adjustment process and obtain the phase information ω of the reference voltage.

[0033] 2. Inverter reactive power control The excitation system can adjust the excitation electromotive force of the synchronous motor, thereby adjusting the output reactive power and ensuring the stability of the terminal voltage.

[0034] The second branch in the figure is a control block diagram of the reactive power regulation system of the grid-building inverter. As shown in the figure, the reactive power regulation system of the grid-building inverter includes: a machine-end voltage controller, which is used to output a voltage regulation instruction according to an input voltage deviation signal; a reactive power controller, which is used to output a reactive power regulation instruction according to a deviation between an input reactive power reference value and an actual reactive power output; and a no-load potential regulation unit, which is used to adjust the internal potential of the inverter according to the no-load potential characteristics of the inverter and the actual operating state to optimize the reactive power output.

[0035] Among them, Qref is the reference reactive power; E0 is the no-load potential; Un is the effective value of the terminal voltage; kq is the reactive-voltage droop coefficient; ki is the integral coefficient, and the amplitude of the reference potential voltage can be finally obtained. VSG gradually approaches the steady-state operating point with continuous voltage regulation, avoiding frequent voltage regulation when reactive power exchange is frequent, thus causing system oscillation, and has better dynamic performance.

[0036] 3. Phase Regulator Excitation Control The third branch in the figure is a control block diagram of the phase regulator excitation system, which includes: A lead-lag compensator is used to perform phase correction on an input voltage deviation signal to improve the dynamic response performance of the system; a main regulator is connected to the lead-lag compensator and is used to calculate and generate a control instruction based on the input voltage deviation signal; a proportional saturator is connected to the main regulator and is used to limit the output range of the control instruction to prevent excessive excitation current; an exciter is connected to the proportional saturator and is used to generate an excitation current according to the control instruction and provide the excitation current to the excitation winding of the phase regulator; a damping unit is connected to the exciter and is used to suppress the oscillation of the system and improve stability.

[0037] Among them, in the lead-lag compensator, Tb / Tc is the lead / lag time constant of the voltage regulator, Ka is its gain and Ta is its time constant in the main regulator. The proportional saturator limits the upper and lower limits of the excitation system output. Te / Ke is the excitation machine time constant / gain.

[0038] As a preferred implementation, the control system measures the voltage signal U_0 of the line, converts it into an effective value through the RMS module, and makes a deviation from the voltage standard value. The output deviation signal is input to the reactive power regulation system of the VSG through a low-pass filter, and the remaining high-frequency signal is input to the excitation system of the phase regulator. The frequency division response of the VSG and the phase regulator is realized. The following is an illustration of the control steps of coordinated control using a voltage sag fault.

[0039] At the moment of voltage sag, the voltage deviation signal is filtered and divided into a high-frequency signal and a low-frequency signal. At this time, the voltage changes rapidly, the high-frequency signal is strong, and the low-frequency signal is weak. The high-frequency deviation signal is given to the phase regulator excitation system, which can give full play to the advantages of the phase regulator's fast response speed and strong overcurrent capacity. The low-frequency deviation signal is given to the inverter's reactive power regulation system, which can effectively protect the inverter.

[0040] During the steady-state period of voltage sag, the voltage deviation signal tends to be stable. At this time, the filtered low-frequency signal is large, while the high-frequency part is small. At this time, the VSG responds to its low-frequency part, which can provide stable reactive support to the system and replace the reactive power output by the phase regulator. The high-frequency command of the phase regulator is small, which can better restore the initial state and leave a margin for the next system change.

[0041] According to the embodiments of the present disclosure, the following technical effects are achieved: The present disclosure provides a coordinated control method of a phase modulator and an inverter. The phase modulator is connected to a grid-building inverter, which can protect the phase modulator in a steady state to prevent it from polluting the power system due to frequency changes. The grid-building inverter is connected to the phase modulator, which can protect the inverter in a transient state to prevent overcurrent damage to the power electronic device. At the same time, through frequency division control, the response of the inverter in the high frequency band can be reduced, frequent charging and discharging of energy storage can be avoided, and the service life of the equipment can be increased. At the same time, the coordinated control of the phase modulator and the inverter can improve the system response speed and enhance the system robustness.

[0042] The following is combined with Figure 3 , a specific embodiment of a method for coordinated control of a phase regulator and a grid-connected inverter provided in the present invention is described.

[0043] like Figure 3 The present disclosure provides a method for coordinated control of a phase regulator and a grid-connected inverter, comprising the following steps: Step S310: Acquire a voltage signal in the power line, and convert the voltage signal into a voltage effective value through an RMS module.

[0044] As a preferred implementation, converting the voltage signal into a voltage effective value by an RMS module includes: Acquire time series data of the voltage signal; perform a square operation on the time series data through an RMS module, and calculate the average value of the data obtained after the square operation within a preset period; perform a square root operation on the average value to obtain a voltage effective value.

[0045] Step S320: determining a voltage deviation signal according to the voltage effective value and a preset voltage standard value.

[0046] As a preferred implementation, the difference between the voltage effective value and a preset voltage standard value is used as a voltage deviation signal.

[0047] Step S330: filtering the voltage deviation signal through the low-pass filter to obtain a low-frequency deviation signal and a high-frequency deviation signal.

[0048] Step S340: input the high-frequency deviation signal into the phase modulator excitation system, and input the low-frequency deviation signal into the inverter reactive power regulation system, so as to realize the frequency division response of the grid-connected inverter and the phase modulator.

[0049] As a preferred embodiment, when a transient process occurs in the power system, the phase regulator excitation system responds to the high-frequency deviation signal and outputs an excitation current adjustment instruction to increase or decrease the reactive power output of the phase regulator to stabilize the voltage; When the power system enters a steady state, the reactive power regulation system of the grid-connected inverter responds to the low-frequency deviation signal, outputs reactive power regulation instructions by adjusting the excitation electromotive force of the synchronous motor, gradually replaces the reactive power output of the phase regulator, and maintains voltage stability.

[0050] As a preferred implementation, when a transient process occurs in the power system, the reactive power regulation system of the grid-connected inverter responds to the low-frequency deviation signal to avoid overload; When the power system enters a steady state, the phase regulator excitation system responds to the high-frequency deviation signal and restores the initial state to ensure that there is sufficient reactive power regulation margin when the system changes next time.

[0051] As a preferred implementation, the grid-connected inverter reactive power regulation system responds to the low-frequency deviation signal, outputs reactive power regulation instructions by adjusting the excitation electromotive force of the synchronous motor, and gradually replaces the reactive power output of the phase regulator, including: Set the minimum reactive power output of the condenser based on the current stability of the system; Gradually reduce reactive power output through the excitation controller of the phase regulator; The grid inverter adjusts the excitation electromotive force of the synchronous motor to output reactive power regulation instructions, gradually increases the reactive power output, and compensates for the reduced reactive power of the phase regulator until the reactive power output of the phase regulator reaches the minimum value.

[0052] According to the embodiments of the present disclosure, the following technical effects are achieved: The present disclosure provides a coordinated control method of a phase modulator and an inverter. The phase modulator is connected to a grid-building inverter, which can protect the phase modulator in a steady state to prevent it from polluting the power system due to frequency changes. The grid-building inverter is connected to the phase modulator, which can protect the inverter in a transient state to prevent overcurrent damage to the power electronic device. At the same time, through frequency division control, the response of the inverter in the high frequency band can be reduced, frequent charging and discharging of energy storage can be avoided, and the service life of the equipment can be increased. At the same time, the coordinated control of the phase modulator and the inverter can improve the system response speed and enhance the system robustness.

[0053] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present disclosure is not limited by the described order of actions, because according to the present disclosure, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily required by the present disclosure.

[0054] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of this disclosure can be achieved, and this document is not limited here.

[0055] The above specific implementations do not constitute a limitation on the protection scope of the present disclosure. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A coordinated control system for phase regulators and grid inverters, characterized in that: include: A grid-connected inverter, a phase modulator, an RMS module and a low-pass filter, wherein the grid-connected inverter comprises a grid-connected inverter reactive power regulation system and a grid-connected inverter active power regulation system, the phase modulator comprises a phase modulator excitation system, and the grid-connected inverter and the phase modulator are connected in parallel to the power system; The RMS module is used to receive a voltage signal, and output a voltage deviation signal to a low-pass filter according to the voltage signal and a voltage standard value; The low-pass filter receives the voltage deviation signal and filters the voltage deviation signal, outputs a high-frequency deviation signal to the phase-shifting excitation system, and outputs a low-frequency deviation signal to the inverter reactive power regulation system; When a transient process occurs in the power system, the phase regulator excitation system responds to the high-frequency deviation signal to maintain voltage stability; When the power system enters a steady state, the inverter reactive power regulation system responds to the low-frequency deviation signal to maintain voltage stability.

2. The system according to claim 1, characterized in that The grid-connected inverter active power regulation system responds to the frequency deviation signal and adjusts its active power output according to a preset active power-frequency droop characteristic.

3. The system according to claim 1, characterized in that The phase modulator excitation system comprises: Lead-lag compensator, used to perform phase correction on input voltage deviation signal to improve the dynamic response performance of the system; A main regulator, connected to the lead-lag compensator, for calculating and generating a control instruction according to an input voltage deviation signal; A proportional saturator connected to the main regulator, used to limit the output range of the control command to prevent excessive excitation current; an exciter, connected to the proportional saturator, for generating an excitation current according to the control instruction and providing the excitation current to the excitation winding of the phase regulator; The damping unit is connected to the exciter and is used to suppress the oscillation of the system and improve the stability.

4. The system according to claim 1, characterized in that The grid-connected inverter reactive power regulation system comprises: The machine-end voltage controller is used to output a voltage adjustment instruction according to the input voltage deviation signal; A reactive power controller is used to output a reactive power regulation instruction according to the deviation between the input reactive power reference value and the actual reactive power output; The no-load potential regulating unit is used to adjust the internal potential of the inverter according to the no-load potential characteristics and actual operating status of the inverter to optimize the reactive power output.

5. The system according to claim 1, characterized in that Also includes: When a transient process occurs in the power system, the phase regulator responds to the high-frequency deviation signal, changes the excitation current, and increases or decreases the reactive power output to maintain voltage stability; When the power system enters a steady state, the grid-connected inverter responds to the low-frequency deviation signal, adjusts the excitation electromotive force of the synchronous motor to adjust the output reactive power, gradually replaces the reactive power output of the phase regulator, and maintains voltage stability.

6. A method for coordinated control of a phase modulator and a grid-connected inverter, based on a coordinated control system of a phase modulator and a grid-connected inverter as claimed in any one of claims 1 to 5, characterized in that: include: Acquire a voltage signal in the power line, and convert the voltage signal into a voltage effective value through an RMS module; Determining a voltage deviation signal according to the voltage effective value and a preset voltage standard value; The voltage deviation signal is filtered by the low-pass filter to obtain a low-frequency deviation signal and a high-frequency deviation signal; The high-frequency deviation signal is input into the phase modulator excitation system, and the low-frequency deviation signal is input into the inverter reactive power regulation system to achieve the frequency division response of the grid-forming inverter and the phase modulator.

7. The method according to claim 6, characterized in that The step of converting the voltage signal into a voltage effective value by using an RMS module includes: Acquiring time series data of the voltage signal; Performing a square operation on the time series data through an RMS module, and calculating the average value of the data obtained after the square operation within a preset period; A square root operation is performed on the average value to obtain a voltage effective value.

8. The method according to claim 6, characterized in that The method of inputting the high-frequency deviation signal into the phase regulator excitation system and the low-frequency deviation signal into the inverter reactive power regulation system to realize the frequency division response of the grid-connected inverter and the phase regulator includes: When a transient process occurs in the power system, the phase regulator excitation system responds to the high-frequency deviation signal and outputs an excitation current adjustment instruction to increase or decrease the reactive power output of the phase regulator and stabilize the voltage; When the power system enters a steady state, the reactive power regulation system of the grid-connected inverter responds to the low-frequency deviation signal, outputs reactive power regulation instructions by adjusting the excitation electromotive force of the synchronous motor, gradually replaces the reactive power output of the phase regulator, and maintains voltage stability.

9. The method according to claim 8, characterized in that The method further comprises: When a transient process occurs in the power system, the reactive power regulation system of the grid-connected inverter responds to the low-frequency deviation signal to avoid overload; When the power system enters a steady state, the phase regulator excitation system responds to the high-frequency deviation signal and restores the initial state to ensure that there is sufficient reactive power regulation margin when the system changes next time.

10. The method according to claim 8, characterized in that The grid-connected inverter reactive power regulation system responds to the low-frequency deviation signal, outputs reactive power regulation instructions by adjusting the excitation electromotive force of the synchronous motor, and gradually replaces the reactive power output of the phase regulator, including: Set the minimum reactive power output of the condenser based on the current stability of the system; Gradually reduce reactive power output through the excitation controller of the phase regulator; The grid inverter adjusts the excitation electromotive force of the synchronous motor to output reactive power regulation instructions, gradually increases the reactive power output, and compensates for the reduced reactive power of the phase regulator until the reactive power output of the phase regulator reaches the minimum value.

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