Electromagnetic scale stabilizing control method and system considering energy amplitude and phase coupling

Abstract

The application discloses an electromagnetic dimensionality stabilizing control method and system considering energy amplitude and phase coupling, and comprises the following steps: based on the variation of the filter capacitor voltage amplitude at the outlet of a converter and the variation of the voltage phase, and combined with the initial setting value of the active power output, the active power reference value of the converter is calculated; based on the variation of the filter capacitor voltage phase at the outlet of the converter and the variation of the voltage amplitude, and combined with the initial setting value of the reactive power output, the reactive power reference value of the converter is calculated; based on the active power reference value and the reactive power reference value of the converter, the current reference value of the axis is calculated; based on the current reference value of the axis and the actual current signal of the axis, the three-phase modulation voltage signal is obtained, and after PWM modulation, the three-phase modulation voltage signal is used for realizing the control of the converter. d The axis and q The axis of the current reference value; based on d The axis and q The axis of the current reference value and d The axis and q The axis of the actual current signal, the three-phase modulation voltage signal is obtained, and after PWM modulation, the three-phase modulation voltage signal is used for realizing the control of the converter. The application can avoid the adverse effects of energy coupling dynamics on system stability caused by the constant power control of power electronic equipment.

Description

Technical Field

[0001] This invention relates to the field of power electronic converter technology, and in particular to an electromagnetic scale stabilization control method and system that considers energy amplitude and phase coupling. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] With the continuous expansion of the high proportion of renewable energy grid connection, the power system is gradually exhibiting an operation pattern dominated by power electronic equipment. Compared with traditional synchronous machines, power electronic converters have the advantages of rapid adjustment and flexible control, but their dynamic characteristics on an electromagnetic scale are more complex, and stability issues are more prominent. In actual operation, the connection of large-scale renewable energy power plants will trigger various new types of oscillation and stability problems, seriously threatening system security.

[0004] When analyzing electromagnetic dynamics, if we assume that power electronic equipment operates under conditions where active power is dominant and reactive power is relatively small, then the energy amplitude and phase dynamics can be approximated as decoupled. In practical renewable energy grid-connected scenarios, the decoupling condition between energy amplitude and phase dynamics holds true in most cases. However, under certain conditions, especially when the power source operates at a high reactive power output, the decoupling condition cannot be well satisfied, and the coupling between energy amplitude and phase dynamics is significantly enhanced. If we still use the decoupling assumption for modeling and control in this situation, it will not only be difficult to accurately characterize the true dynamics of the system, but it may also overlook the positive feedback loop caused by the coupling effect, leading to biased judgments of system stability and insufficient damping compensation.

[0005] Therefore, additional power control that only targets energy amplitude or phase dynamics is insufficient to meet stability requirements when decoupling conditions cannot be fully met. Summary of the Invention

[0006] To address the aforementioned issues, this invention proposes an electromagnetic scale stabilization control method and system that considers energy amplitude and phase coupling. Stabilization control is performed based on the dynamic characteristics of energy amplitude and phase coupling, thereby maintaining system stability even when the energy amplitude and phase coupling of the system increases.

[0007] In some implementations, the following technical solutions are adopted: An electromagnetic scale-stabilized control method considering energy amplitude-phase coupling includes: Based on the changes in the amplitude and phase of the voltage of the filter capacitor at the converter outlet, and combined with the initial setting value of the active power output, the reference value of the active power of the converter is calculated. Based on the change in phase and amplitude of the voltage of the filter capacitor at the converter outlet, and combined with the initial setting value of reactive power output, the reference value of reactive power of the converter is calculated. Based on the active power reference value, reactive power reference value of the converter, and the voltage amplitude at the grid connection point, the following calculations are performed: d shaft and q Shaft current reference value; based on d shaft and q Shaft current reference value and d shaft and q The actual current signal of the shaft is used to obtain a three-phase modulated voltage signal, which is then modulated by PWM to control the converter.

[0008] As a further step, the active power reference value of the converter is calculated, specifically as follows: ; in, This is the active power reference value for the converter. This is the initial setting value for the active power of the converter. and These are the phase of the filter capacitor voltage at the converter outlet and its reference value, respectively. Under steady-state conditions, the two are equal. and These are the voltage amplitude of the filter capacitor at the converter outlet and its reference value, respectively, which are equal under steady-state conditions; , These are the droop coefficients.

[0009] As a further option, the droop coefficient satisfy: ; in, Active power droop control coefficient Reliability coefficient during the tuning process This is the steady-state voltage at the filter capacitor. This is the initial setting value for the active power of the converter; The equivalent conductance of the parallel connection of the filter capacitor branch is given.

[0010] As a further option, the droop coefficient Specifically: ; in, This is the initial setting value for the reactive power of the converter.

[0011] As a further step, the reactive power reference value of the converter is calculated, specifically as follows: ; in, This is the reference value for the reactive power of the converter. This is the initial setpoint for the reactive power of the converter. and These are the phase of the filter capacitor voltage at the converter outlet and its reference value, respectively. Under steady-state conditions, the two are equal. and These are the voltage amplitude of the filter capacitor at the converter outlet and its reference value, respectively, which are equal under steady-state conditions; , These are the droop coefficients.

[0012] As a further option, the droop coefficient satisfy: ; in, Sag coefficient Reliability coefficient during the tuning process This is the initial setting value for the active power of the converter. This refers to the magnitude of the steady-state voltage across the filter capacitor. The equivalent conductance of the parallel connection of the filter capacitor branch is given.

[0013] As a further option, the droop coefficient Specifically: .

[0014] In other embodiments, the following technical solutions are adopted: An electromagnetically scale-stabilized control system considering energy amplitude-phase coupling includes: The active power reference value calculation module is configured to calculate the active power reference value of the converter based on the change in voltage amplitude and voltage phase of the filter capacitor at the converter outlet, combined with the initial setting value of active power output. The reactive power reference value calculation module is configured to calculate the reactive power reference value of the converter based on the change in phase and amplitude of the voltage of the filter capacitor at the converter outlet, combined with the initial set value of reactive power output. The power control module is configured to calculate based on the converter's active power reference value, reactive power reference value, and grid connection point voltage amplitude. d shaft and q Shaft current reference value; The current control module is configured to be based on d shaft and q Shaft current reference value and d shaft and qThe actual current signal of the shaft is used to obtain a three-phase modulated voltage signal, which is then modulated by PWM to control the converter.

[0015] In other embodiments, the following technical solutions are adopted: A terminal device includes a processor and a memory, the processor being used to implement instructions; the memory being used to store multiple instructions adapted to be loaded by the processor and executed by the above-described electromagnetic scale stabilization control method considering energy amplitude phase coupling.

[0016] In other embodiments, the following technical solutions are adopted: A computer-readable storage medium storing a plurality of instructions adapted for loading and execution by a processor of a terminal device of the above-described electromagnetic scale stabilization control method considering energy amplitude phase coupling.

[0017] Compared with the prior art, the beneficial effects of the present invention are: (1) The present invention introduces additional droop control for the coupling dynamics of energy amplitude and phase in converter control. By changing the instantaneous power output characteristics of the converter under electromagnetic scale, the coupling of energy amplitude and phase in the system is always kept in a negative feedback relationship. It can maintain the critical stability of the coupling dynamics of energy amplitude and phase at the filter capacitor under the condition of no explicit damping, and avoid the adverse effects of energy coupling dynamics caused by constant power control of power electronic equipment on system stability.

[0018] Other features and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] Figure 1 This is a simplified system diagram of a converter grid connection scenario in an embodiment of the present invention; Figure 2 This is a diagram illustrating the instantaneous power in an embodiment of the present invention; Figure 3 This is a coupled block diagram of a converter grid-connected scenario in an embodiment of the present invention; Figure 4 This is a schematic diagram of a typical power electronic equipment grid-connected system in an embodiment of the present invention; Figure 5 This illustrates the power flow direction of a typical power electronic equipment grid-connected system in an embodiment of the present invention. Figure 6 As described in the embodiments of the present invention P 01 =0.3 pu, Q 01 The eigenvalue distribution when =0.6 pu; Figure 7 This invention introduces an eigenvalue distribution that incorporates additional control considering energy coupling characteristics in its embodiments. Figure 8 This is a grid-connected system for network-type devices in this embodiment of the invention; Figure 9 This is the basic control structure of the grid-connected converter in the embodiments of the present invention; Figure 10 This is a schematic diagram of an active power control structure that additionally considers energy amplitude and phase coupling in an embodiment of the present invention; Figure 11 This is a schematic diagram of a reactive power control structure that takes into account energy amplitude and phase coupling in an embodiment of the present invention; Figures 12(a)-(c) are schematic diagrams of the simulation results of active power, reactive power and voltage under active power output state without considering energy coupling disturbance in the embodiments of the present invention; Figures 13(a)-(c) are schematic diagrams of the simulation results of active power, reactive power and voltage after introducing stabilization control considering coupling in the active power output state in the embodiment of the present invention. Figures 14(a)-(c) are schematic diagrams of the simulation results of active power, reactive power and voltage under active absorption state without considering energy coupling disturbance in the embodiments of the present invention; Figures 15(a)-(c) are schematic diagrams of the simulation results of active power, reactive power and voltage after introducing stabilization control considering coupling under active power absorption state in the embodiments of the present invention. Detailed Implementation

[0020] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0021] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0022] Example 1 In one or more embodiments, an electromagnetic scale-based stabilization control method considering energy amplitude-phase coupling is disclosed, combined with... Figure 9 Specifically, it includes the following process: First, the voltage and current measurement module measures the three-phase voltage and three-phase current signals at the grid connection point of the grid-connected converter; then, based on the phase angle of the reference coordinate system provided by the phase-locked loop, the three-phase voltage and three-phase current signals are transformed to obtain... dq Voltage and current signals in a rotating coordinate system; The power control module uses the input active power reference value. Reactive power reference value and the voltage amplitude at the grid connection point Calculations yielded d Shaft current reference value and q Current reference value And input it into the current control module; whereby the grid connection point voltage amplitude based on dq The voltage signal is calculated in a rotating coordinate system.

[0023] The current control module is based on the input dq The shaft current reference value and current signal are used to obtain a modulated voltage through PI control, etc., and then... dq / abc The coordinate transformation yields the three-phase modulated voltage signal; the converter modulation module outputs a pulse width modulation signal based on the modulated voltage signal to achieve grid-connected control of the converter.

[0024] Among them, combined Figure 10 Based on the changes in the amplitude and phase of the filter capacitor voltage at the converter outlet, and combined with the initial setpoint of the active power output, the reference value of the active power of the converter is calculated; specifically: ; in, This is the active power reference value for the converter. This is the initial setting value for the active power of the converter. and These are the phase of the filter capacitor voltage at the converter outlet and its reference value, respectively. Under steady-state conditions, the two are equal. and These are the voltage amplitude of the filter capacitor at the converter outlet and its reference value, respectively, which are equal under steady-state conditions; , These are the droop coefficients.

[0025] At the same time, combined Figure 11 Based on the changes in the phase and amplitude of the voltage across the filter capacitor at the converter outlet, and combined with the initial setpoint for reactive power output, the reference value for reactive power of the converter is calculated; specifically: ; in, This is the reference value for the reactive power of the converter. This is the initial setpoint for the reactive power of the converter. and These are the phase of the filter capacitor voltage at the converter outlet and its reference value, respectively. Under steady-state conditions, the two are equal. and These are the voltage amplitude of the filter capacitor at the converter outlet and its reference value, respectively, which are equal under steady-state conditions; , These are the droop coefficients.

[0026] The above method is applicable when the power supply is operating at a large reactive power output state, the decoupling conditions between energy amplitude and phase dynamics cannot be well met, and the coupling between energy amplitude and phase dynamics is significantly enhanced.

[0027] It is generally assumed that power electronic equipment operates under conditions where active power is dominant and reactive power is relatively small. In this case, the energy amplitude and phase dynamics can be approximated as decoupled. (1) When the converter operates under active power absorption conditions, the fundamental mechanism of instability is: when the instantaneous active power output of the energy storage converter is under constant control, the filter capacitor directly connected to the power supply... C Energy amplitude of 1 The changes cannot obtain corresponding suppressive active power regulation from the converter, resulting in unstable oscillation of the system energy amplitude.

[0028] To address the system instability issue caused by the aforementioned negative damping effect, considering the voltage amplitude of the filter capacitor at the outlet of the energy storage converter... and energy amplitude There is a positive correlation between them, which can be introduced. Control is used to dynamically dampen the magnitude of the energy vector of the filter capacitor; the control process can be expressed as: ; in, For the proposed The controlled droop coefficient; and These are the voltage amplitude of the filter capacitor at the outlet of the energy storage converter and the reference voltage amplitude, respectively. Under steady-state conditions, the two values ​​are equal.

[0029] When the voltage amplitude of the filter capacitor increases, the instantaneous active power output of the converter decreases; conversely, when the voltage amplitude decreases, the instantaneous active power output of the converter increases. Therefore, when the converter exhibits unstable energy amplitude in active power absorption mode, an induction function is introduced into the converter control. Control can help the system achieve dynamic stability of the network energy vector magnitude.

[0030] (2) When the converter operates under active power output conditions, the fundamental mechanism of instability lies in the fact that when the new energy outputs instantaneous reactive power Q 01 When kept constant, the filter capacitor directly connected to the power supply C The energy phase change on 1 cannot enable the new energy grid-connected converter to provide instantaneous reactive power that can prevent further changes in its energy phase, thus causing dynamic instability of the system energy phase.

[0031] To address the system instability caused by the aforementioned negative damping effect, considering the energy phase... Phase angle with filter capacitor voltage There is a 2x relationship, which can be introduced Control, specifically: ; in, For the proposed The controlled droop coefficient; and These are the reactive power reference value and initial setting value of the energy storage converter, respectively; and These are the voltage phase angle and voltage phase angle reference values ​​of the filter capacitor at the output of the grid converter, respectively. Under steady-state conditions, the two values ​​are equal.

[0032] When the phase of the voltage across the converter's outlet filter capacitor increases, the converter's inductive instantaneous reactive power output increases (while reducing capacitive reactive power output); when the phase of the capacitor voltage decreases, the inductive reactive power output decreases (or the capacitive reactive power output increases). Therefore, in the converter's active power output mode, when phase dynamics become unstable, additional... Controlling the phase dynamics of the network energy vector can effectively stabilize the network's energy vector.

[0033] In practical renewable energy grid-connected scenarios, the decoupling condition between energy amplitude and phase dynamics holds true in most cases. However, under certain operating conditions, especially when the power supply operates at a large reactive power output, the decoupling condition cannot be well satisfied, and the coupling between energy amplitude and phase dynamics is significantly enhanced. If the instantaneous power control strategy described above is still used in this case, it may lead to biased judgment of system stability and insufficient damping compensation.

[0034] Therefore, this embodiment further proposes an electromagnetic scale stabilization control method that considers energy amplitude and phase coupling. This method can maintain system stability even when the system energy amplitude and phase coupling are enhanced, providing effective support for the safe and stable operation of high-proportion new energy grid-connected systems.

[0035] The electromagnetic scale-stabilized control method considering energy amplitude-phase coupling is described in detail below: I. Mechanism Analysis of the Coupling Dynamics of Energy Amplitude and Energy Phase (1) Mathematical modeling of a single-inductor grid-connected system To highlight the coupling relationship between energy amplitude and phase at the electromagnetic scale, the active power output of the power source and line resistance are initially ignored in the modeling process, assuming that only reactive power transmission exists in the system. Under this assumption, the off-diagonal submatrix A related to reactive power transmission in the system matrix is... 12 and A 21 The element size is significantly larger than that of the diagonal submatrix A associated with active power transmission. 11 and A 22 This results in the system's energy amplitude and phase dynamics exhibiting a significant strong coupling characteristic.

[0036] Based on this, to facilitate the revelation of the inherent laws of coupling dynamics, we start with the simplest grid-connected model, assuming that the power electronic converter is directly connected to the external power grid, neglecting the line impedance between the converter and the external power grid, and assuming that the external power grid consists of an ideal voltage source and equivalent impedance, such as... Figure 1 As shown; Figure 1 middle, For the filter inductor inside the converter, It is the equivalent inductance of the external power grid.

[0037] At this point, the grid-connected power electronic equipment system can be equivalent to the converter power supply passing through an inductor. L 2. Directly connected to an ideal voltage source. Among them, and These are the reference values ​​for active and reactive power of the grid-connected converter, respectively. and These represent the instantaneous active and reactive power injected into the ideal voltage source, respectively.

[0038] Combination Figure 2 The instantaneous power indicator shown can establish a dynamic relationship between the system network energy and the instantaneous power, specifically: (1) in, and Inductors L Energy amplitude and energy phase on 2 This indicates the rated angular velocity of rotation at a power frequency of 50Hz.

[0039] Furthermore, ignoring the active power transmission of the system, or assuming that the active power output of the power source is small and the line resistance is ignored, linearizing equation (1) yields: (2) in, This is a linearized representation of the active power of the converter. This is a linearized representation of the reactive power of the converter. This is a linearized representation of the energy amplitude of a three-phase inductor network.

[0040] (2) Stability mechanism analysis of single-inductor grid-connected system Under constant power control conditions, the coupling relationship of the converter grid-connected system is as follows: Figure 3 As shown, according to the dynamic mechanism of instantaneous power driving changes in network energy state, the active power on a component directly determines the change in its energy amplitude, while reactive power directly drives the change in energy phase. However, in the modeling assumptions, the system has neither active power transmission nor resistive dissipation. Therefore, the change in energy amplitude cannot be damped by active power feedback, and similarly, the change in energy phase cannot be suppressed by reactive power channels. This means that the coupling dynamics between the two are essentially without damping.

[0041] When active power transmission and line resistance are neglected, the values ​​of all system matrix elements are related to the reactive power in equilibrium. Under this condition, the steady-state reactive power relationship of the system can be characterized by the following equation: (3) in, For inductance L 2. Inductor current vector amplitude, For the inductive instantaneous reactive power injected into the three-phase inductor, This is the inductance value of the three-phase inductor.

[0042] If and only if Q res When equation (4) is satisfied, the inductance L The instantaneous power change can suppress the coupling dynamics of energy amplitude and phase, thereby maintaining the coupling dynamics in a critical stable state.

[0043] (4) At this point, a cross-negative feedback mechanism is formed between energy amplitude and energy phase: disturbances in energy amplitude change the reactive power injected into the element, thereby causing a change in energy phase, which in turn drives the adjustment of active power to suppress further amplitude shift; similarly, disturbances in energy phase drive changes in active power, causing adjustments in energy amplitude, and the change in amplitude feeds back to reactive power, thus suppressing phase shift. The two coupling channels restrain each other, so that although the coupled dynamics do not have a direct damping effect, they can still maintain critical stability on an electromagnetic scale.

[0044] once Q resBeyond the critical range, the coupling relationship between energy amplitude and phase changes from negative feedback to positive feedback. At this point, energy amplitude disturbances are no longer suppressed, but instead drive energy phase shifts through reactive power changes. These phase shifts, in turn, amplify the amplitude disturbances through active power changes. Under the influence of positive feedback, energy amplitude and phase mutually promote each other, ultimately leading to oscillations or divergent instability in the coupled dynamics.

[0045] In summary, in a single-inductor grid-connected system, the stability characteristics of the energy amplitude and phase coupling dynamics depend on the gain signs of the two coupling channels. When the gains have opposite signs, the instantaneous active and reactive power cross-suppress each other, causing the amplitude and phase dynamics to counterbalance each other, and the system can maintain critical stability. However, when the gains have the same sign, the coupling relationship evolves into positive feedback, the original balance is disrupted, and the system is prone to instability.

[0046] II. Instability Mechanism Analysis of Energy Amplitude and Phase Coupling Dynamics in Grid-Connected Power Electronic Equipment Systems (1) Dynamic characteristics of grid-connected systems like Figure 4 As shown, in a typical grid-connected power electronic equipment system, the grid-connected converter is connected to the external power grid through inductors, resistors, capacitors, and ground conductivity components, forming an equivalent topology for power electronic equipment accessing an infinite power system. Grid-connected converters typically employ a constant active and constant reactive power control strategy, exhibiting constant power source characteristics externally.

[0047] for Figure 4 The typical parameters of the system shown are shown in Table 1: Table 1 Parameters of Power Electronic Equipment Grid-connected System

[0048] for Figure 4 The system shown is used to perform power flow calculations based on the system parameters in Table 1 to obtain the power flow under steady-state conditions. The power flow direction in the system is defined as follows: Figure 5 As shown.

[0049] in, and These are the filter inductor and filter resistor of the mesh filter, respectively; and These are the inductance and resistance of the equivalent series connection of electrical lines in a grid-connected scenario, respectively. and These are the capacitance and conductance of the equivalent parallel portion of electrical lines in a grid-connected scenario, respectively. and These refer to the instantaneous active and reactive power in electrical lines during grid-connected scenarios.

[0050] When a grid-connected converter primarily outputs active power while exchanging relatively little reactive power, the network energy amplitude and phase dynamics at the electromagnetic scale are approximately decoupled. Based on the aforementioned mechanism of network energy and instantaneous power interaction, it can be seen that the instability of the grid-connected system at this time often stems from the negative damping element introduced by the constant power control of the converter in terms of energy amplitude or phase dynamics.

[0051] The foregoing describes how to improve damping characteristics by adding active or reactive power control loops under two different operating conditions of active output and active absorption, thereby effectively improving the electromagnetic scale stability of power electronic equipment under near-decoupling conditions.

[0052] However, when the reactive power output of the power electronic equipment in the system increases, it will break the original approximate decoupling condition. For example, the output at the grid connection port may simultaneously contain both active and reactive power (such as...). , When this happens, the dynamic characteristics of the system change significantly. At this point, a mathematical model as shown in equation (5) can be established: (5) Among them, A 11 A 12 A 21 and A 22 These are the four sub-matrices obtained by dividing the system matrix A according to the network energy amplitude and phase; Indicates the network energy phase. This represents the network energy amplitude.

[0053] (1) Submatrix A 11 The specific elements in the text are: when hour, ; when hour, ; in, The rated angular velocity for rotation at a power frequency of 50Hz; For the inflow element i The instantaneous active power of the branch circuit; outflow element i The instantaneous active power of the branch circuit; For components i The active power consumed by the corresponding equivalent resistance or conductance of the branch; For components i The network energy amplitude; For components i +1 network energy amplitude.

[0054] (2) Submatrix A12 The specific elements in the text are: when hour, ; when hour, ; in, Rated angular velocity of rotation at 50Hz power frequency; For the inflow element i The instantaneous reactive power of the branch circuit; outflow element i The instantaneous reactive power of the branch circuit; The rated angular velocity of the voltage and current vectors after standardization; For components i The network energy amplitude; For components i +1 network energy amplitude; For components i -1 is the network energy amplitude.

[0055] (3) Submatrix A 21 The specific elements in the text are: when hour, ; when hour, ; (4) Submatrix A 22 The specific elements in the text are: when hour, ; when hour, .

[0056] In addition to the elements mentioned above, submatrix A 11 A 12 A 21 and A 22 All other elements in the expression are zero. Also, please note the following regarding the element expressions above: At that time, element Does not exist; when At that time, element It does not exist. Furthermore, it can be observed that, except for the submatrix... Except for the special case of time, the submatrix formed by the remaining elements exists , The numerical relationship.

[0057] In this case, submatrix A in the system matrix 11 With A 22 The elements in the middle are no longer approximately zero, meaning that the energy amplitude and phase dynamics are no longer decoupled. If additional droop control is introduced into the converter control based on the decoupling assumption, although the system damping level is improved, the eigenvalue distribution of the state-space A matrix in equilibrium state, such as... Figure 6 As shown, this indicates that the system still has eigenvalues ​​with positive real parts, leading to unstable oscillations. It should be noted that these unstable eigenvalues ​​cannot pass through A... 11 Or A 22 Eigenvalues ​​are used to effectively characterize the system, and their formation mechanism mainly originates from A. 12 With A 21 The coupling effect between the energy amplitude and phase represented.

[0058] Therefore, although additional droop control improves system damping, it is insufficient to eliminate instability caused by the coupling dynamics between energy amplitude and phase. System instability at the electromagnetic scale is not solely dominated by energy amplitude or phase dynamics; the coupling dynamics between the two are also a key factor affecting the oscillation and instability of grid-connected power electronic equipment systems.

[0059] (2) Analysis of the instability mechanism dominated by dynamic energy amplitude and phase coupling Based on the electromagnetic scale dynamic modeling of power electronic equipment, submatrix A 12 and A 21 The main diagonal elements characterize the coupling relationship between the energy amplitude and phase of the components in the circuit. For circuit components other than the converter outlet, the coupling coefficients of the corresponding elements always have opposite signs and do not change with the operating state, thus forming a stable negative feedback channel. In contrast, the filter capacitor at the converter outlet is subject to constant power control constraints. When the steady-state reactive power output of the converter is large, the corresponding coupling elements in the submatrix may have the same sign. At this time, the energy amplitude or phase change on the capacitor acts on the instantaneous power through the coupling channel: when the energy amplitude is disturbed, it will drive the instantaneous reactive power on the capacitor to change, which in turn causes a change in the energy phase; and the change in phase further acts on the instantaneous active power on the capacitor, amplifying the further dynamic change in the energy amplitude. This forms a closed-loop positive feedback structure on the capacitor, thus bringing the risk of system instability.

[0060] On the other hand, the energy amplitude-phase coupling relationship between capacitors and inductors in the circuit is reflected in submatrix A. 12 and A 21The coupling coefficients appear in pairs. Although these coupling coefficients adjust with changes in the active and reactive power distribution of the system, they always maintain a relationship of equal magnitude and opposite signs. Specifically, when the energy amplitude of a component changes, it drives a change in the instantaneous reactive power of its adjacent components, which in turn causes a change in the energy phase of the adjacent components; this phase change further affects the instantaneous active power of the component, and ultimately has a reverse effect on its own energy amplitude dynamics. Thus, a natural negative feedback structure is formed, thereby avoiding the aforementioned instability phenomenon.

[0061] In summary, the constant power control of the power electronic converter is based on reactive power output. Q 01 When the value is large, it will break the critical stability condition between the energy amplitude and the phase coupling coefficient at the outlet filter capacitor, and the risk of grid-connected system instability will increase significantly.

[0062] III. Electromagnetic Scale Stabilization Control Strategy Based on Network Energy Coupling Mechanism To address the aforementioned instability and oscillation problem caused by the energy coupling characteristics of the outlet filter capacitor, this embodiment proposes introducing additional droop control in the converter control to address the dynamic coupling between energy amplitude and phase. The basic idea is to alter the instantaneous power output characteristics of the converter under electromagnetic dimensions, ensuring that the coupling between energy amplitude and phase in the system maintains a consistently negative feedback relationship. Specifically, the corresponding coefficient of this coupling relationship should be maintained at [value missing]. On the one hand, this is consistent with the inherent characteristics of other line components not directly connected to the power supply; on the other hand, even when the converter's steady-state output reactive power is 0 pu, the coefficient corresponding to its coupling dynamics can still be maintained at [value missing]. This ensures that the coupling relationship between the system's energy amplitude and phase remains in a stable negative feedback relationship. Combined with... Figure 10 and Figure 11 The corresponding active and reactive power control strategies are as follows: (6) (7) in, This is the active power reference value for the converter. This is the initial setting value for the active power of the converter. and These are the phase of the filter capacitor voltage at the converter outlet and its reference value, respectively. Under steady-state conditions, the two are equal. and These are the voltage amplitude of the filter capacitor at the converter outlet and its reference value, respectively, which are equal under steady-state conditions; , These are the droop coefficients; This is the reference value for the reactive power of the converter. This is the initial setting value for the reactive power of the converter. , These are the droop coefficients.

[0063] The following explains the range of values ​​for each droop coefficient: (1) Sag coefficient satisfy: ; in, Active power droop control coefficient The reliability coefficient during the tuning process is typically taken as a value of . This is the steady-state voltage at the filter capacitor. This is the initial setting value for the active power of the converter; The equivalent conductance of the parallel connection of the filter capacitor branch is given.

[0064] (2) Sag coefficient satisfy: ; in, Sag coefficient The reliability coefficient during the tuning process is typically taken as a value of . This is the initial setting value for the active power of the converter. This refers to the magnitude of the steady-state voltage across the filter capacitor. The equivalent conductance of the parallel connection of the filter capacitor branch is given.

[0065] This embodiment establishes a clear mathematical relationship between each droop coefficient and the key operating characteristics of the system, thereby enabling quantifiable design and adaptive adjustment of parameters.

[0066] (3) Sag coefficient Specifically: ; (4) Sag coefficient Specifically: .

[0067] Therefore, it can be seen that the active power output of the converter depends on the phase angle of the voltage across the filter capacitor at the converter outlet. The change occurs, and its trend depends on the steady-state reactive power setpoint. The reactive power output of the converter varies with the voltage amplitude of the filter capacitor at the converter outlet. The direction of the change is also related to the initial reactive power setting. Under steady-state conditions, this control remains locked and does not affect the system operating point. If... When positive, if the phase of the grid connection point voltage is... If the voltage amplitude increases, the active power output of the converter will decrease accordingly; if the voltage amplitude increases... As the voltage increases, the reactive power output of the converter will also increase. Through this adjustment mechanism, the critical stability of the energy amplitude and phase coupling dynamics at the filter capacitor can be maintained without explicit damping, thus avoiding the adverse effects of energy coupling dynamics caused by constant power control of power electronic equipment on system stability.

[0068] After introducing the additional control shown in equations (6) and (7) in this embodiment, the eigenvalue distribution of the system state-space equation matrix A is as follows: Figure 7 As shown, the results indicate that the system no longer has right-half-plane eigenvalues, and the unstable modes are effectively suppressed. This demonstrates that when power electronic devices operate at high reactive power output levels, disrupting the decoupling conditions between energy amplitude and phase dynamics, the effectiveness of the additional power control can still be maintained by further introducing active and reactive power droop control that considers coupling characteristics, building upon existing additional power control designs for approximate decoupling conditions. This also improves the electromagnetic scale stability of power electronic devices under different power output conditions.

[0069] IV. Simulation Comparison Build such a simulation platform Figure 8 The grid-connected system shown is a grid-connected device.

[0070] (1) Active power output status of grid converter In the initial equilibrium state, the grid-connected converter operates in active power output mode. The initial setpoint for the active power of the grid-connected converter is set to 0.3 pu, and the initial setpoint for the reactive power is set to 0.6 pu. An unconsidered energy amplitude-phase coupling is introduced into the grid-connected system. Control and Control (i.e., control of reactive power reference value) Control, and adjust the active power reference value. (Control). At 0.01s, a voltage disturbance of -0.01pu is applied to the system voltage. The simulation results of active power, reactive power and voltage after the disturbance are shown in Figure 12(a)-(b). As can be seen from the figure, under the disturbance, the converter terminal voltage and active and reactive power all diverge, and the grid-connected system becomes unstable.

[0071] Keeping the converter output constant, when the active power and reactive power control considering energy amplitude-phase coupling of this embodiment is further introduced into the grid-connected system, the same disturbance is applied, and the simulation results of active power, reactive power and voltage are shown in Figures 13(a)-(b), respectively. The results show that the additional stabilization control strategy considering energy coupling can significantly improve the dynamic response of the system's active power output state: the voltage and power quickly recover to stability after the disturbance, showing good damping characteristics.

[0072] (2) Active power absorption state of grid converter Similarly, when the grid-connected converter absorbs active power, the initial setpoint value of the active power of the grid-connected converter is set. Initial setting value of reactive power And introduce into the grid-connected system a phenomenon that does not consider energy amplitude-phase coupling. Control and Control (i.e., control of reactive power reference value) Control, and adjust the active power reference value. (Control). At 0.01s, a voltage disturbance of -0.01 pu is applied to the system voltage. The simulation results of the active power, reactive power and voltage after the disturbance are shown in Figure 14(a)-(b). As can be seen from the figure, under the disturbance, the converter terminal voltage and active and reactive power all diverge, and the grid-connected system becomes unstable.

[0073] Keeping the converter output constant, when the active power and reactive power control considering energy amplitude-phase coupling in this embodiment is further introduced into the grid-connected system, the same disturbance is applied, and the simulation results of active power, reactive power and voltage are shown in Figures 15(a)-(b), respectively. The results show that the additional stabilization control strategy considering energy coupling can significantly improve the dynamic response of the system under active power absorption state: the voltage and power quickly recover to stability after the disturbance, showing good damping characteristics.

[0074] In summary, when power electronic equipment operates under conditions where active power is dominant and reactive power is relatively small, the dynamics of energy amplitude and phase can be approximated as decoupled. Under this typical operating condition, the system can effectively satisfy the decoupling conditions of energy amplitude and phase, resulting in a low steady-state reactive power level. Under these conditions, the droop coefficient introduced by the control strategy in this embodiment... and (By definition, this is an adaptive parameter related to the steady-state reactive power output of power electronic equipment.) Its value is small, and the effect of droop control can be approximately ignored. The dynamics of power electronic equipment are mainly determined by… or The control strategy is dominant, corresponding to the electromagnetic scale dynamic process of the equipment in active output or active absorption states, respectively.

[0075] However, when the system's reactive power level increases and the power flow distribution causes the decoupling condition between energy amplitude and phase to no longer hold, the active and reactive power control strategy considering energy amplitude-phase coupling proposed in this embodiment will adaptively increase with the increase in reactive power level. At this point, electromagnetic scale stabilization control of power electronic equipment under different operating conditions can be achieved, thereby ensuring the stability of the system over a wider operating range.

[0076] Example 2 In one or more embodiments, an electromagnetic scale-stabilized control system considering energy amplitude-phase coupling is disclosed, specifically including: The active power reference value calculation module is configured to calculate the active power reference value of the converter based on the change in voltage amplitude and voltage phase of the filter capacitor at the converter outlet, combined with the initial setting value of active power output. The reactive power reference value calculation module is configured to calculate the reactive power reference value of the converter based on the change in phase and amplitude of the voltage of the filter capacitor at the converter outlet, combined with the initial set value of reactive power output. The power control module is configured to calculate based on the converter's active power reference value, reactive power reference value, and grid connection point voltage amplitude. d shaft and q Shaft current reference value; The current control module is configured to be based on d shaft and q Shaft current reference value and d shaft and q The actual current signal of the shaft is used to obtain a three-phase modulated voltage signal, which is then modulated by PWM to control the converter.

[0077] The calculated active power reference value for the converter is as follows: ; in, This is the active power reference value for the converter. This is the initial setting value for the active power of the converter. and These are the phase of the filter capacitor voltage at the converter outlet and its reference value, respectively. Under steady-state conditions, the two are equal. and These are the voltage amplitude of the filter capacitor at the converter outlet and its reference value, respectively, which are equal under steady-state conditions; , These are the droop coefficients.

[0078] The calculated reference value for the reactive power of the converter is as follows: ; in, This is the reference value for the reactive power of the converter. This is the initial setpoint for the reactive power of the converter. and These are the phase of the filter capacitor voltage at the converter outlet and its reference value, respectively. Under steady-state conditions, the two are equal. and These are the voltage amplitude of the filter capacitor at the converter outlet and its reference value, respectively, which are equal under steady-state conditions; , These are the droop coefficients.

[0079] It should be noted that the specific implementation methods of the above modules are exactly the same as those in Example 1, and will not be described in detail again.

[0080] Example 3 In one or more embodiments, a terminal device is disclosed, comprising a processor and a memory, the processor being used to implement instructions; the memory being used to store multiple instructions adapted to be loaded by the processor and executed by the electromagnetic scale stabilization control method considering energy amplitude phase coupling as described in Embodiment 1.

[0081] It should be understood that in this embodiment, the processor can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc.

[0082] Memory may include read-only memory and random access memory, and provides instructions and data to the processor. A portion of memory may also include non-volatile random access memory. For example, memory may also store information about the device type.

[0083] In the implementation process, each step of the above method can be completed by the integrated logic circuits in the processor hardware or by software instructions.

[0084] Example 4 A computer-readable storage medium storing a plurality of instructions adapted for loading and execution by a processor of a terminal device of the electromagnetic scale stabilization control method considering energy amplitude phase coupling as described in Embodiment 1.

[0085] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. An electromagnetic scale-based stabilization control method considering energy amplitude-phase coupling, characterized in that, include: Based on the changes in the voltage amplitude and voltage phase of the filter capacitor at the converter outlet, combined with the initial setting value of active power output, the reference value of active power of the converter is calculated. Based on the change in phase and amplitude of the voltage of the filter capacitor at the converter outlet, and combined with the initial setting of reactive power output, the reference value of reactive power of the converter is calculated. Based on the active power reference value, reactive power reference value of the converter, and the voltage amplitude at the grid connection point, the following calculations are performed: d shaft and q Shaft current reference value; based on d shaft and q Shaft current reference value and d shaft and q The actual current signal of the shaft is used to obtain a three-phase modulated voltage signal, which is then modulated by PWM to control the converter. The active power reference value of the converter is calculated as follows: ； in, This is the active power reference value for the converter. This is the initial setting value for the active power of the converter. and These are the phase of the filter capacitor voltage at the converter outlet and its reference value, respectively. Under steady-state conditions, the two are equal. and These are the voltage amplitude of the filter capacitor at the converter outlet and its reference value, respectively, which are equal under steady-state conditions; , These are the droop coefficients; The sagging coefficient satisfy: ； in, Active power droop control coefficient Reliability coefficient during the tuning process This is the steady-state voltage at the filter capacitor. This is the initial setting value for the active power of the converter; The equivalent conductance of the filter capacitor branch in parallel; The calculated reference value for the reactive power of the converter is as follows: ； in, This is the reference value for the reactive power of the converter. This is the initial setpoint for the reactive power of the converter. and These are the phase of the filter capacitor voltage at the converter outlet and its reference value, respectively. Under steady-state conditions, the two are equal. and These are the voltage amplitude of the filter capacitor at the converter outlet and its reference value, respectively, which are equal under steady-state conditions; , These are the droop coefficients; The sagging coefficient satisfy: ； in, Sag coefficient Reliability coefficient during the tuning process This is the initial setting value for the active power of the converter. This refers to the magnitude of the steady-state voltage across the filter capacitor. The equivalent conductance of the parallel connection of the filter capacitor branch is given.

2. The electromagnetic scale stabilization control method considering energy amplitude and phase coupling as described in claim 1, characterized in that, The sagging coefficient Specifically: ; in, This is the initial setting value for the reactive power of the converter.

3. The electromagnetic scale stabilization control method considering energy amplitude and phase coupling as described in claim 1, characterized in that, Sag coefficient Specifically: 。 4. An electromagnetically scale-stabilized control system considering energy amplitude-phase coupling, characterized in that, An electromagnetic scale stabilization control method considering energy amplitude and phase coupling as described in any one of claims 1-3, comprising: The active power reference value calculation module is configured to calculate the active power reference value of the converter based on the change in voltage amplitude and voltage phase of the filter capacitor at the converter outlet, combined with the initial setting value of active power output. The reactive power reference value calculation module is configured to calculate the reactive power reference value of the converter based on the change in phase and amplitude of the voltage of the filter capacitor at the converter outlet, combined with the initial set value of reactive power output. The power control module is configured to calculate based on the converter's active power reference value, reactive power reference value, and grid connection point voltage amplitude. d shaft and q Shaft current reference value; The current control module is configured to be based on d shaft and q Shaft current reference value and d shaft and q The actual current signal of the shaft is used to obtain a three-phase modulated voltage signal, which is then modulated by PWM to control the converter.

5. A terminal device comprising a processor and a memory, the processor for implementing instructions; the memory for storing multiple instructions, characterized in that, The instructions are adapted to be loaded by a processor and executed by the electromagnetic scale stabilization control method considering energy amplitude phase coupling as described in any one of claims 1-3.

6. A computer-readable storage medium storing a plurality of instructions, characterized in that, The instructions are adapted to be loaded by the processor of a terminal device and executed by the electromagnetic scale stabilization control method considering energy amplitude phase coupling as described in any one of claims 1-3.

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