Mesh-forming type matching control low-frequency oscillation suppression method

Abstract

The invention relates to the technical field of power distribution of a power system, in particular to a network construction type matching control low-frequency oscillation suppression method. The invention discloses a network configuration type matching control low-frequency oscillation suppression method, and the method comprises the following steps: S1, building a small signal control model of network configuration type matching control, and obtaining an original DC outer loop synchronization characteristic under small signal disturbance; s2, establishing a small signal control improved model of an additional high-pass filtering forward path based on the small signal control model, and obtaining improved DC outer loop synchronization characteristics under small signal disturbance; and S3, analyzing the original direct current outer ring synchronization characteristic and the improved direct current outer ring synchronization characteristic, obtaining a leading phase related to a high-pass filtering forward path in the small signal control improved model, and obtaining an optimal leading phase by adjusting parameters of the high-pass filtering forward path to suppress low-frequency oscillation. The critical phase of a direct-current voltage synchronous outer loop is effectively improved, and the low-frequency oscillation problem of the converter caused by direct-current side constant power dynamics is suppressed.

Description

Technical Field

[0001] The present invention relates to the technical field of power distribution of electric power systems, and in particular to a method for suppressing low-frequency oscillations of a grid-type matching control. Background Art

[0002] The construction of a new power system with new energy as the main body, and the penetration rate of new energy power generation represented by wind power and photovoltaic power generation is constantly increasing. In recent years, domestic and foreign scholars have proposed a variety of grid-forming (GFM) converter control strategies, which enable the converter to simulate the operating characteristics of synchronous generators, have the ability to independently build voltage, and have the ability to actively support the power grid.

[0003] The most typical grid-connected converter control strategy is the virtual synchronous generator (VSG). However, in actual wind power generation, in order to improve the utilization of wind energy, the front-stage DC / DC converter usually operates in the maximum power point tracking (MPPT) mode, which cannot control the DC voltage stability. Traditional VSG control uses active power-frequency control to achieve synchronization, and cannot take into account the control of the DC side voltage.

[0004] In order to simultaneously realize DC side voltage control and converter synchronization, a grid-based control method based on DC voltage synchronization is proposed, which does not require active power but only requires DC voltage to achieve synchronization. This method uses the dynamics of the converter DC side capacitor to achieve converter synchronization, which can ensure the maximum power point tracking control (MPPT) of the previous stage.

[0005] Therefore, the energy of the converter DC bus capacitor is used to simulate the energy of the synchronous machine rotor, and a matching control strategy based on this principle is generated. The converter and the synchronous generator have a certain duality in structure. There is a matching relationship between the converter DC bus voltage and the synchronous machine rotor angular frequency, and between the converter DC current and the synchronous machine mechanical torque. Multiply by the coefficient The frequency ω is obtained by integrating the reference voltage phase θ, which provides a clear time reference point for the converter. This control strategy is also called DC voltage synchronization control strategy.

[0006] Unlike virtual synchronous control, matching control only needs to measure the DC bus voltage, which makes matching control have the advantage of low latency. In addition, other control strategies require that the control of AC and DC quantities be independent of each other in time scale, but matching control does not have this requirement because it avoids the interaction between the AC and DC ends. Matching control can be directly used to synchronize the GFM converter with the AC grid.

[0007] However, due to the constant power dynamics of the DC loop, the matching control scheme is prone to produce unstable low-frequency oscillations (LFO), which reduces the stability and reliability of the system and poses serious safety risks to the power supply. Summary of the invention

[0008] In order to solve the problem that the matching control scheme is prone to produce unstable low-frequency oscillation due to the constant power dynamics of the DC circuit, the present invention provides a network-type matching control low-frequency oscillation suppression method.

[0009] In a first aspect, the present invention provides a method for suppressing low-frequency oscillations by mesh-type matching control, which adopts the following technical solution: A method for suppressing low-frequency oscillation by mesh-type matching control, comprising the following steps: S1, establish a small signal control model of network matching control to obtain the original DC outer loop synchronization characteristics under small signal disturbance; S2, based on the small signal control model, an improved small signal control model with an additional high-pass filter forward path is established to obtain the improved DC outer loop synchronization characteristics under small signal disturbance; S3, analyze the original DC outer loop synchronization characteristics and the improved DC outer loop synchronization characteristics, obtain the leading phase related to the high-pass filter forward path in the improved small signal control model, and obtain the optimal leading phase by adjusting the parameters of the high-pass filter forward path to suppress low-frequency oscillation.

[0010] Optionally, in step S1, the step of establishing a small signal control model for meshing type matching control includes: S1-1, select the reference value of the DC bus voltage as input and the actual value of the DC bus voltage as output; S1-2, determine the main variables that affect the system dynamics, including: DC bus voltage, AC side voltage frequency, AC side voltage phase angle, DC side input AC side power and DC side capacitance; S1-3, derive multiple equations describing the dynamic behavior of the small-signal model based on the main variables and small-signal disturbances; S1-4, based on multiple equations describing the dynamic behavior of the small signal model, the transfer function of the small signal control model of matching control is derived.

[0011] Optionally, in step S1-3, deriving an equation describing the dynamic behavior of the model further includes: converting the dynamic change of the DC bus voltage into an equation of the AC side voltage frequency and the AC side voltage phase angle:

[0012] Where ω represents the AC side voltage frequency, is the rated frequency, is the DC bus voltage, is the DC bus voltage reference value, θ is the AC side voltage phase angle, represents the DC voltage control coefficient; under small signal disturbance, the AC side voltage phase angle θ is expressed as:

[0013] Where s is the complex frequency operator.

[0014] Optionally, in step S1-3, deriving an equation describing the dynamic behavior of the model further includes: a calculation equation from the small signal disturbance amount of the phase angle on the AC side to the small signal disturbance amount of the transmission power on the AC side; The relationship between the AC side transmission power and the AC side voltage phase angle θ is:

[0015] Where P is the AC side transmission power, E is the converter port voltage, U is the grid connection point voltage, x is the transmission line impedance, and δ is the line impedance angle; In the case of small disturbance, the calculation equation for the small signal disturbance of the phase angle on the AC side to the small signal disturbance of the power transmitted on the AC side is equivalent to:

[0016] Where ΔP is the small signal disturbance of AC side transmission power, Δθ is the small signal disturbance of AC side phase angle, is the proportionality coefficient.

[0017] Optionally, in step S1-3, the equation describing the dynamic behavior of the small signal model includes a calculation equation for the small signal disturbance amount of the DC bus voltage derived from the power input from the DC side to the AC side according to the power balance equation: Under small disturbances, the active power balance of the DC capacitor is expressed as:

[0018] in is the power input from the DC side to the AC side, is the small signal disturbance of the power input from the DC side to the AC side, is the power of the DC side of the previous input inverter, is the DC side capacitance, is the rated value of DC bus voltage, is the small signal disturbance of DC bus voltage, t is the time; because It has a constant power characteristic, so the disturbance calculation equation is:

[0019] Where s is the complex frequency operator.

[0020] Optionally, the transfer function of the small signal control model of the matching control derived in S1-4 specifically includes: Open-loop transfer function of the small-signal control model of matching control Calculated as:

[0021] Closed-loop transfer function of the small signal control model of matching control Calculated as: .

[0022] Optionally, the specific steps of establishing the small signal control model of the additional high-pass filter forward path in S2 include: on the basis of establishing the small signal control model of the meshed matching control, in the process of converting the dynamic change of the DC bus voltage into the AC side voltage frequency and the AC side voltage phase angle, adding a high-pass filter forward path, and the AC side voltage phase angle θ is expressed as:

[0023] Optionally, deriving the transfer function of the small signal control improvement model of the matching control specifically includes: The open-loop and closed-loop transfer functions of the control reference-output are Open-loop transfer function of the small-signal control improved model of matching control Calculated as:

[0024] Open-loop transfer function of the small-signal control improvement model of matching control Calculated as:

[0025] in, is the proportional coefficient of the high-pass filter forward path, and T is the time constant.

[0026] Optionally, the transfer function of the integrated small signal control model is used to calculate the original DC outer loop synchronization characteristic equation:

[0027] By substituting the comprehensive transfer function into the relational expression, we can get the improved DC outer loop synchronization characteristic equation as follows: .

[0028] Optionally, in step S3, the original DC outer loop synchronization characteristic equation and the improved DC outer loop synchronization characteristic equation are analyzed to obtain the leading phase and Association; Adjust the parameters of the high-pass filter forward path including: Adjust the high-pass filter forward path proportional coefficient .

[0029] In summary, the present invention has the following beneficial technical effects: By properly selecting the parameters of the additional high-pass filter forward path, the critical phase of the DC voltage synchronization outer loop can be effectively improved, the stability margin of the system can be improved, and the low-frequency oscillation problem of the converter caused by the constant power dynamics on the DC side can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flow chart of a method for suppressing low-frequency oscillation by mesh-type matching control according to an embodiment of the present invention.

[0031] Figure 2 It is a block diagram of the matching control structure of an embodiment of the present invention.

[0032] Figure 3 It is a schematic diagram of the small signal control model structure of the matching control of an embodiment of the present invention.

[0033] Figure 4 4 is a structural block diagram of an additional high-pass filter forward path according to an embodiment of the present invention.

[0034] Figure 5 It is a schematic diagram of the structure of a small signal improved model of an additional high-pass filter forward path according to an embodiment of the present invention.

[0035] Figure 6 The closed-loop poles of the embodiment of the present invention are Change trajectory diagram.

[0036] Figure 7 1 is a Bode diagram of the DC outer loop of the system under different parameters of the embodiment of the present invention.

[0037] Figure 8 Schematic diagram of voltage given step simulation result of an embodiment of the present invention.

[0038] Fig. 9 Schematic diagram of input power step simulation results of an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following is combined with Figure 1 -Attached Fig. 9 The present invention is described in further detail.

[0040] Example 1 Reference Figure 1 A method for suppressing low-frequency oscillation by mesh-type matching control in this embodiment includes the following steps: S1, establish a small signal control model of the grid-type matching control to obtain the original DC outer loop synchronization characteristics under small signal disturbances; the closed-loop dynamics of the GFM converter depends on the AC circuit dynamics, the DC side load / source dynamics, and the control loop used. In order to evaluate the impact of different synchronization loops on stability, we established a single-loop (SISO) small signal model to describe the reference-output dynamics of the DC side voltage. In order to perform transient stability analysis on the matching control, a small signal control model of the matching control was built, which is used to describe the dynamic characteristics of the DC voltage from reference to output. The specific steps of building the model include: S1-1, select the reference value of the DC bus voltage as input and the actual value of the DC bus voltage as output; S1-2, determine the main variables that affect the system dynamics, including: DC bus voltage, AC side voltage frequency, AC side voltage phase angle, DC side input AC side power and DC side capacitance; S1-3, derive multiple equations describing the dynamic behavior of the small-signal model based on the main variables and small-signal disturbances; Specifically, it includes: converting the dynamic change of DC bus voltage into equations for AC side voltage frequency and AC side voltage phase angle; calculating equations for small signal disturbance of AC side phase angle to small signal disturbance of power transmitted to AC side; deriving the calculation equations for small signal disturbance of DC bus voltage from power input from DC side to AC side according to power balance equation; Reference Figure 2 This includes deriving the calculation equation for the small signal disturbance of the DC bus voltage from the power input from the DC side to the AC side based on the power balance equation: Under small disturbances, the active power balance of the DC capacitor is expressed as:

[0041] in is the power input from the DC side to the AC side, is the small signal disturbance of the power input from the DC side to the AC side, is the power of the DC side of the previous input inverter, is the DC side capacitance, is the rated value of DC bus voltage, is the small signal disturbance of DC bus voltage, t is the time; because It has a constant power characteristic, so the disturbance calculation equation is:

[0042] Where s is the complex frequency operator.

[0043] The equation for converting the dynamic change of DC bus voltage into AC side voltage frequency and AC side voltage phase angle is:

[0044] Where ω represents the AC side voltage frequency, is the rated frequency, is the DC bus voltage, is the DC bus voltage reference value, θ is the AC side voltage phase angle, represents the DC voltage control coefficient; under small signal disturbance, the AC side voltage phase angle θ is expressed as:

[0045] Where s is the complex frequency operator.

[0046] It also includes: a calculation equation from the small signal disturbance amount of the phase angle on the AC side to the small signal disturbance amount of the transmission power on the AC side; The relationship between the AC side transmission power and the AC side voltage phase angle θ is:

[0047] Where P is the AC side transmission power, E is the converter port voltage, U is the grid connection point voltage, x is the transmission line impedance, and δ is the line impedance angle; In the case of small disturbance, the calculation equation for the small signal disturbance of the phase angle on the AC side to the small signal disturbance of the power transmitted on the AC side is equivalent to:

[0048] Where ΔP is the small signal disturbance of AC side transmission power, Δθ is the small signal disturbance of AC side phase angle, is the proportionality coefficient.

[0049] S1-4, based on multiple equations describing the dynamic behavior of the small signal model, the transfer function of the small signal control model of matching control is derived.

[0050] Reference Figure 3 , matching control is used to generate the frequency and phase angle of the AC output, and the open-loop transfer function of the small signal control model of the matching control is Calculated as:

[0051] Closed-loop transfer function of the small signal control model of matching control Calculated as: .

[0052] From the model shown in Figure 3, it can be seen that there are two integrators in the closed-loop control diagram of the DC side voltage. The function of the first integrator is to generate a phase angle according to the frequency. The second integrator is included in the transfer function of the DC link voltage and the active power. These two integrators will produce a phase lag of 180°, thereby reducing the phase margin of the closed-loop control. Therefore, the grid-type converter based on matching control has an LFO problem when the DC side is connected to constant power, and the damping needs to be increased. The essence of matching control is that the DC bus capacitor of the converter and the synchronous generator have a certain structural duality, so the DC capacitor energy of the converter can be used to simulate the rotor kinetic energy of the synchronous machine. Among them, the rotor time constant of the synchronous motor can be dual with the inertia time constant of the DC capacitor, but the damping of the synchronous motor cannot be directly found in the capacitor. The damping can only be simulated by adding other physical elements such as parallel / series resistors, which may bring adverse effects such as energy loss or heat generation. Therefore, the purpose of increasing the equivalent damping is considered from the perspective of improving the control loop.

[0053] S2, based on the small signal control model, an improved small signal control model with an additional high-pass filter forward path is established to obtain the improved DC outer loop synchronization characteristics under small signal disturbance; Reference Figure 4 On the basis of traditional grid-type matching control, the transfer function link from voltage to phase angle is replaced by a PI-like link, and a forward path with a high-pass filter is used to replace it. Finally, the power-to-frequency transfer function link can be equivalent to a low-pass filter plus an integral link. That is, on the basis of establishing a small signal control model for grid-type matching control, in the process of converting the dynamic change of the DC bus voltage into the AC side voltage frequency and the AC side voltage phase angle, a forward path with a high-pass filter is added, and the AC side voltage phase angle θ is expressed as: .

[0054] Reference Figure 5 The open-loop and closed-loop transfer functions of the control reference-output are Open-loop transfer function of the small-signal control improvement model of matching control Calculated as:

[0055] Open-loop transfer function of the small-signal control improvement model of matching control Calculated as:

[0056] in, is the proportional coefficient of the high-pass filter forward path, and T is the time constant.

[0057] S3, analyze the original DC outer loop synchronization characteristics and the improved DC outer loop synchronization characteristics, obtain the leading phase related to the high-pass filter forward path in the improved small signal control model, and obtain the optimal leading phase by adjusting the parameters of the high-pass filter forward path to suppress low-frequency oscillation.

[0058] The transfer function of the integrated small signal control model is used to calculate the original DC outer loop synchronization characteristic equation:

[0059] By substituting the comprehensive transfer function into the relational expression, we can get the improved DC outer loop synchronization characteristic equation as follows: .

[0060] The leading phase and the improved DC outer loop synchronous characteristic equation are obtained by analyzing the original DC outer loop synchronous characteristic equation. Association; Adjust the parameters of the high-pass filter forward path including: Adjust the high-pass filter forward path proportional coefficient Compared with the original DC outer loop synchronization characteristic equation, the improved DC outer loop synchronization characteristic is equivalent to increasing the first-order coefficient on the numerator, which can provide a certain leading phase for the DC voltage synchronization outer loop. By analyzing this formula, it can be seen that The larger the coefficient is, the more leading phase can be provided, so the leading phase provided by the link can be adjusted by adjusting this coefficient. Dynamically speaking, a term negatively correlated with the differential of the output is added to the controlled object, which provides an effect opposite to the rate of change when the DC voltage fluctuates. It is essentially a damping effect, realizing additional damping.

[0061] Finally, the above low-frequency oscillation suppression method is verified, and a set of matching control parameter values ​​is selected as shown in the following table

[0062] Combining the system equations of the three parameters can comprehensively describe the behavior of the system in different aspects. From the entry of the input signal to the response output of the system, from the dynamic change process to the final stable state, all can be comprehensively considered through the combined equation, thus providing a more complete perspective for a deeper understanding of the working mechanism of the system. The system state equation is established as follows:

[0063]

[0064]

[0065] Written as a state-space expression:

[0066] Using the state space to obtain the system eigenvalue, we can get:

[0067] Bring in , ,T, Numerical value, solved

[0068]

[0069]

[0070] From the analysis, we can see that the eigenvalues ​​are all in the left half plane of the complex plane. At this time, the system is stable and the selected solution is effective.

[0071] The root trajectory is Figure 6 As shown, from the root locus, it can be seen that the system can be guaranteed to be stable.

[0072] In order to explore the influence of this improvement on the low-frequency stability of the system, is 0.2, 0.4, 0.8. Figure 7 It can be seen that under the three sets of parameters, the amplitude of the dynamic characteristics of the synchronous outer loop remains basically unchanged, while the phase leads -180° in the low frequency band, and as As the value increases, the phase lead of the dynamic characteristics of the synchronous outer loop by -180° also increases, which effectively corrects the extreme phase characteristics of the DC voltage synchronous outer loop.

[0073] The proposed improved control method with an additional high-pass filter forward loop can significantly improve the stability of the DC bus voltage. Figure 8 shows the dynamic response of the DC capacitor voltage and active power when the DC voltage is given by a step, and Figure 9 shows the dynamic response of the DC capacitor voltage and active power when the input power is stepped. Compared with the traditional control method (Scheme 1), the proposed improved control method (Scheme 2) has much better dynamic response in terms of both DC voltage and active power, which proves that the proposed improved method can significantly enhance the system damping and suppress low-frequency oscillations. As the leading phase of the additional high-pass filter forward loop increases, the system's damping effect on low-frequency oscillations becomes stronger, the oscillation dynamic time after control switching becomes shorter, and the oscillation amplitude becomes smaller.

[0074] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. As for the method disclosed in the embodiment, since it corresponds to the system disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0075] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0076] The above disclosure is only a preferred embodiment of the present invention, but the present invention is not limited thereto. Any non-creative changes that can be thought of by a person skilled in the art, as well as several improvements and modifications made without departing from the principle of the present invention, should fall within the protection scope of the present invention.

Claims

1. A method for suppressing low-frequency oscillation by mesh-type matching control, characterized in that: The following steps are involved: S1, establish a small signal control model of network matching control to obtain the original DC outer loop synchronization characteristics under small signal disturbance; S2, based on the small signal control model, an improved small signal control model with an additional high-pass filter forward path is established to obtain the improved DC outer loop synchronization characteristics under small signal disturbance; S3, analyze the original DC outer loop synchronization characteristics and the improved DC outer loop synchronization characteristics, obtain the leading phase related to the high-pass filter forward path in the improved small signal control model, and obtain the optimal leading phase by adjusting the parameters of the high-pass filter forward path to suppress low-frequency oscillation.

2. The method for suppressing low-frequency oscillation by mesh matching control according to claim 1, characterized in that: In step S1, the steps of establishing a small signal control model for meshing type matching control include: S1-1, select the reference value of the DC bus voltage as input and the actual value of the DC bus voltage as output; S1-2, determine the main variables that affect the system dynamics, including: DC bus voltage, AC side voltage frequency, AC side voltage phase angle, DC side input AC side power and DC side capacitance; S1-3, derive multiple equations describing the dynamic behavior of the small-signal model based on the main variables and small-signal disturbances; S1-4, based on multiple equations describing the dynamic behavior of the small signal model, the transfer function of the small signal control model of matching control is derived.

3. The method for suppressing low-frequency oscillation by mesh matching control according to claim 2, characterized in that: In step S1-3, deriving an equation describing the dynamic behavior of the model includes: converting the dynamic change of the DC bus voltage into an equation of the AC side voltage frequency and the AC side voltage phase angle: Where ω represents the AC side voltage frequency, is the rated frequency, is the DC bus voltage, is the DC bus voltage reference value, θ is the AC side voltage phase angle, represents the DC voltage control coefficient; under small signal disturbance, the AC side voltage phase angle θ is expressed as: Where s is the complex frequency operator.

4. The method for suppressing low-frequency oscillation by mesh-type matching control according to claim 3, characterized in that: In step S1-3, the equations describing the dynamic behavior of the model are derived, which also include: a calculation equation from the small signal disturbance of the phase angle on the AC side to the small signal disturbance of the transmission power on the AC side; The relationship between the AC side transmission power and the AC side voltage phase angle θ is: Where P is the AC side transmission power, E is the converter port voltage, U is the grid connection point voltage, x is the transmission line impedance, and δ is the line impedance angle; In the case of small disturbance, the calculation equation for the small signal disturbance of the phase angle on the AC side to the small signal disturbance of the power transmitted on the AC side is equivalent to: Where ΔP is the small signal disturbance of AC side transmission power, Δθ is the small signal disturbance of AC side phase angle, is the proportionality coefficient.

5. The method for suppressing low-frequency oscillation by mesh-type matching control according to claim 4, characterized in that: In step S1-3, the equation describing the dynamic behavior of the small signal model also includes a calculation equation for the small signal disturbance amount of the DC bus voltage derived from the power input from the DC side to the AC side according to the power balance equation: Under small disturbances, the active power balance of the DC capacitor is expressed as: in is the power input from the DC side to the AC side, is the small signal disturbance of the power input from the DC side to the AC side, is the power of the DC side of the previous input inverter, is the DC side capacitance, is the rated value of DC bus voltage, is the small signal disturbance of DC bus voltage, t is the time; because It has a constant power characteristic, so the disturbance calculation equation is: Where s is the complex frequency operator.

6. The method for suppressing low-frequency oscillation by mesh-type matching control according to claim 5, characterized in that: The transfer function of the small signal control model of matching control derived in S1-4 specifically includes: Open-loop transfer function of the small-signal control model of matching control Calculated as: Closed-loop transfer function of the small signal control model of matching control Calculated as: 。 7. The method for suppressing low-frequency oscillation by mesh-type matching control according to claim 6, characterized in that: The specific steps of establishing the small signal control model with an additional high-pass filter forward path in S2 include: on the basis of establishing the small signal control model of the meshed matching control, in the process of converting the dynamic change of the DC bus voltage into the AC side voltage frequency and the AC side voltage phase angle, adding a high-pass filter forward path, the AC side voltage phase angle θ is expressed as: 。 8. The method for suppressing low-frequency oscillation by mesh matching control according to claim 7, characterized in that: The transfer function of the improved small signal control model of matching control is derived specifically including: The open-loop and closed-loop transfer functions of the control reference-output are Open-loop transfer function of the small-signal control improved model of matching control Calculated as: Open-loop transfer function of the small-signal control improved model of matching control Calculated as: in, is the proportional coefficient of the high-pass filter forward path, and T is the time constant.

9. The method for suppressing low-frequency oscillation by mesh-type matching control according to claim 8, characterized in that: The transfer function of the integrated small signal control model is used to calculate the original DC outer loop synchronization characteristic equation: By substituting the comprehensive transfer function into the relational expression, we can get the improved DC outer loop synchronization characteristic equation as follows: 。 10. The method for suppressing low-frequency oscillation by mesh matching control according to claim 9, characterized in that: In step S3, the original DC outer loop synchronization characteristic equation and the improved DC outer loop synchronization characteristic equation are analyzed to obtain the leading phase and association; Adjusting the parameters of the high-pass filter forward path includes: Adjusting the high-pass filter forward path proportional coefficient .

Images