A method for adaptive control of frequency reference of a net-following type converter phase-locked loop
Patent Information
- Application Number
- CN202611108854.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-24
- Publication Date
- 2026-08-21
AI Technical Summary
[0006]针对现有锁相环暂态稳定性提升方案在电压跌落与电网频率偏移并发的复合故障工况下存在的固有局限，本发明的目的在于提出一种跟网型变流器锁相环频率参考自适应控制方法，以有功功率偏差作为频率参考修正的反馈信号，动态调整锁相环频率参考值（并非电流参考值），并与现有锁相环暂态稳定性提升方案兼容叠加，在无需广域通信与系统参数辨识的前提下，实现对电网频率动态偏移的自适应跟踪，以保障复合扰动下跟网型变流器的暂态同步稳定性
一、从根源上解决了复合故障下的频率失配问题。现有锁相环暂态稳定性提升控制方案以固定的额定频率为参考，在电网频率发生持续偏移时无法跟随，导致相位差持续积累直至失稳。本发明以有功功率偏差作为频率参考修正的反馈信号，使锁相环频率参考值随电网频率动态变化，从根源上消除了固定频率参考与动态电网频率之间的冲突，有效遏制了相位差的单调积累。
Smart Images
Figure CN122620508A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of equipment control technology for use with power supplies or similar power supply systems, and specifically relates to a phase-locked loop frequency reference adaptive control method for grid-connected converters. Background Technology
[0002] With the large-scale integration of renewable energy, grid-connected converters are widely used in power systems. These converters rely on phase-locked loops (PLLs) to achieve synchronization with the grid, and their transient synchronization stability is particularly important under severe disturbances. Among existing methods for improving the transient stability of PLLs in grid-connected converters, PLL damping loop control, PLL freeze control, and phase angle deviation compensation control have received widespread attention due to their reliance on local measurements and ease of implementation. All three schemes use the rated frequency as the fixed frequency reference for the PLL and effectively enhance transient stability during voltage dips by adding damping, temporarily freezing the integrator, or dynamically adjusting the current output angle, demonstrating good performance in pure voltage dip fault scenarios.
[0003] However, the above schemes all use the rated frequency as a reference when calculating the frequency deviation used for stability control. This design has significant limitations under combined faults involving voltage dips and grid frequency deviations. Specifically, when a sustained frequency deviation occurs in the grid after a fault, the phase-locked loop (PLL), under the strong regulation of the above schemes, is kept near the rated frequency and cannot track the actual changes in the grid frequency, resulting in a continuous deviation between its output frequency and the grid frequency. This deviation drives the phase difference to accumulate, eventually causing a monotonically increasing phase angle and triggering synchronization instability. Because it is difficult to coordinate a fixed frequency reference with the constantly changing grid frequency, simply adjusting the control parameters or trigger thresholds of existing schemes cannot solve the problem at its root.
[0004] Existing improvement schemes for frequency deviation conditions have the following shortcomings: First, some schemes suppress phase accumulation by removing the integral element in the feedback path, but this weakens their ability to suppress fault instability and has limited effectiveness under combined disturbances; Second, some schemes only provide fixed compensation for the phase jump caused by the fault and cannot track the dynamic phase drift caused by the continuous accumulation of frequency deviation; Third, none of the above schemes are effectively compatible with existing voltage drop transient stability improvement methods, and it is difficult to cope with pure voltage drop, pure frequency deviation and the combined disturbance of the two at the same time.
[0005] Furthermore, obtaining the true frequency of the power grid for compensation often relies on parameters that are difficult to obtain online, such as grid impedance and system inertia, or requires the use of wide-area communication networks, resulting in extremely high engineering implementation costs. Therefore, it is necessary to propose a phase-locked loop frequency reference adaptive control method that relies solely on local power measurement, requires no parameter identification or wide-area communication, and is compatible with existing transient stability improvement schemes, in order to ensure the transient synchronization stability of grid-connected converters under combined disturbances. Summary of the Invention
[0006] To address the inherent limitations of existing phase-locked loop (PLL) transient stability enhancement schemes under combined fault conditions of voltage dips and grid frequency deviations, this invention aims to propose a frequency reference adaptive control method for PLLs in grid-connected converters. This method uses active power deviation as the feedback signal for frequency reference correction, dynamically adjusting the PLL frequency reference value (not the current reference value). It is compatible with and can be superimposed on existing PLL transient stability enhancement schemes. Without requiring wide-area communication and system parameter identification, it achieves adaptive tracking of dynamic grid frequency deviations, ensuring the transient synchronization stability of grid-connected converters under combined disturbances.
[0007] To achieve the above objectives, the present invention adopts the following technical solution: A phase-locked loop frequency reference adaptive control method for a grid-type converter includes the following steps: Step 1: Real-time acquisition of three-phase voltage and current at the ports of the grid-connected converter, calculation and acquisition of the active power measurement value of the grid-connected converter. And it is processed by low-pass filtering.
[0008] When the system contains multiple grid-connected converters The sum of the active power output of each grid-connected converter at the point of common coupling is obtained, and then transmitted to each grid-connected converter in the cluster via the station's communication bus. This is done when the system contains only a single grid-connected converter. The local output active power measurement value is directly obtained. All the above signals originate from the local control system of the grid-connected converter, without the need for a wide-area monitoring communication network, nor is it necessary to identify parameters such as grid impedance and system inertia.
[0009] Step 2: Use the steady-state value of active power before the fault occurs as the reference value for active power. Calculate the active power deviation .
[0010] Records can be generated and saved during normal operation and remain unchanged after a fault occurs. When the system contains multiple grid-connected converters... The reference value of the total active power of the cluster is obtained and sent to each grid-type converter in the cluster via the station communication bus.
[0011] Step 3: Determine the feedback gain based on Lyapunov stability theory. The quantitative design lower bound ensures that the closed-loop system of the phase-locked loop frequency reference adaptive control of the grid converter satisfies local input state stability within the defined domain. Must meet: , In the formula, As the upper bound of the frequency deviation between the sending and receiving power grids, in actual engineering, it can be conservatively taken according to the upper limit of the allowable deviation range of system frequency specified in the power grid regulations. The Thevenin equivalent voltage amplitude on the grid side; The summation current amplitude is the resultant current amplitude after the vector superposition of the output current phasors of all grid-connected converters at the common coupling point. When the system contains only a single grid-connected converter, it degenerates into the local output current amplitude of that single grid-connected converter. To determine the power angle at the stable equilibrium point of the grid-connected system with the grid-connected converter, based on the power balance condition... Confirmed. The above conditions are met. The design conditions ensure that the steady-state error of the closed-loop system is limited to the domain. Within this system, local input state stability is satisfied.
[0012] Step 4: Using the feedback gain determined in Step 3 Deviation from the active power calculated in step 2 The product of these two values serves as a correction factor for the phase-locked loop (PLL) frequency reference value. The frequency reference value of the phase-locked loop is dynamically corrected to obtain the corrected frequency reference value. This replaces the fixed rated phase-locked loop frequency reference value in traditional control. .
[0013] Step 5: Use the corrected PLL frequency reference value obtained in Step 4. This invention, applied to existing phase-locked loop (PLL) transient stability enhancement control schemes, works in conjunction with these schemes to output a corrected PLL phase, achieving transient synchronous stability enhancement for grid-connected converters under combined fault disturbances such as pure voltage dips, pure frequency offsets, and both concurrently. The modification in this invention is limited to the frequency reference input of the PLL control link and does not affect the current control command generation stage. The internal structure and control logic of existing PLL transient stability enhancement control schemes remain unchanged. The superposition methods for the three existing PLL transient stability enhancement control schemes are as follows: a. When the existing solution is a phase-locked loop damped loop control, When the frequency reference input to the phase-locked loop (PLL) damping loop control is fed in, the PLL proportional-integral controller parameters and damping feedback coefficient remain unchanged. After incorporating the method of this invention, the original oscillation suppression effect of the PLL damping loop control is fully preserved under pure voltage dip conditions; when the grid frequency continues to deviate, the corrected frequency reference value... It can follow the grid frequency in real time, which makes up for the inherent limitation of phase-locked loop damping loop control which uses a fixed rated frequency as a reference and cannot cope with frequency deviation conditions. This makes the solution have the ability to ensure transient synchronization and stability under complex fault disturbances.
[0014] b. When the existing solution is phase-locked loop freeze control, The frequency reference input to the phase-locked loop (PLL) freeze control remains unchanged, as do the PLL freeze trigger logic and the angle holding mechanism during the freeze period. After incorporating the method of this invention, the original voltage dip protection effect of the PLL freeze control is fully preserved under pure voltage dip conditions. When the grid frequency continuously deviates, the frequency reference before freeze triggering dynamically follows the grid frequency, making the angle held at the freeze moment closer to the actual grid phase. This effectively alleviates the problem of static phase error accumulation caused by a fixed frequency reference under frequency deviation conditions, and also provides transient synchronization stability assurance under complex fault disturbances.
[0015] c. When the existing solution is phase angle deviation compensation control, The frequency reference input to the phase angle deviation compensation control remains unchanged, as do the state feedback coefficients and other control logic. After applying the method of this invention, the original alignment effect between the control dq coordinate system and the system dq coordinate system of the phase angle deviation compensation control is fully preserved under pure voltage drop conditions; when the grid frequency continues to deviate, the corrected phase-locked loop frequency reference value... This enables the phase-locked loop to follow the dynamic changes in the power grid frequency, compensating for the problem of continuous accumulation of coordinate system alignment error when the phase angle deviation compensation control uses a fixed rated frequency as a reference under frequency offset conditions. It also has the ability to ensure transient synchronization stability under complex fault disturbances.
[0016] Compared with the prior art, the advantages of the present invention are: I. This invention fundamentally solves the frequency mismatch problem under complex faults. Existing phase-locked loop (PLL) transient stability improvement control schemes use a fixed rated frequency as a reference. When the grid frequency continuously deviates, they cannot keep up, leading to the continuous accumulation of phase difference until instability occurs. This invention uses the active power deviation as the feedback signal for frequency reference correction, causing the PLL frequency reference value to change dynamically with the grid frequency. This fundamentally eliminates the conflict between the fixed frequency reference and the dynamic grid frequency, effectively curbing the monotonic accumulation of phase difference.
[0017] II. The feedback gain has a quantitative design basis. Based on Lyapunov stability theory, this invention derives the feedback gain. k c The quantitative design lower bound provides a basis for engineering parameter tuning, avoiding the uncertainty of trial and error based on experience.
[0018] Third, it is fully compatible with existing transient stability improvement schemes. The modification of this invention is limited to replacing the fixed rated PLL frequency reference value at the PLL frequency reference input terminal with a modified frequency reference value, which acts on the frequency reference input terminal of the PLL control link, rather than the current control command generation stage. It does not change the internal structure and control logic of existing PLL damping loop control, PLL freeze control, and phase angle deviation compensation control. After adding the method of this invention, the control effect of the above-mentioned existing schemes under pure voltage drop conditions is fully preserved, while gaining the ability to cope with frequency deviation and combined disturbance conditions.
[0019] Fourth, it relies solely on local measurements, eliminating the need for wide-area communication and parameter identification. The active power measurement and reference values required by this invention are all taken from the local control system of the grid-connected converter. There is no need to obtain system parameters that are difficult to identify online, such as grid impedance and system inertia, nor is there a need to deploy a wide-area monitoring and communication network. The engineering implementation cost is low, making it suitable for the promotion and application of large-scale grid-connected converter clusters. Attached Figure Description
[0020] Figure 1 The present invention provides a flowchart of a phase-locked loop frequency reference adaptive control method for a grid-type converter.
[0021] Figure 2 This is the control block diagram of the phase-locked loop (PLL) for a grid-type converter.
[0022] Figure 3 This is a control block diagram of the frequency reference adaptive control strategy of the present invention.
[0023] Figure 4 This is a schematic diagram of the topology and control framework of a grid-connected system containing multiple grid-connected converters.
[0024] Figure 5(a) and Figure 5(b) show the dynamic response curves of active power before and after the phase-locked loop damping loop control is superimposed with the present invention, respectively; Figure 5(c) and Figure 5(d) show the dynamic response curves of active power before and after the phase-locked loop freezing control is superimposed with the present invention, respectively; Figure 5(e) and Figure 5(f) show the dynamic response curves of active power before and after the phase angle deviation compensation control is superimposed with the present invention, respectively.
[0025] Figures 6(a) and 6(b) show the active power response under a 5Hz frequency step drop condition with and without additional phase-locked loop (PLL) freezing control, respectively, and with the present invention superimposed. Figures 6(c) and 6(d) show the active power response under a 3Hz frequency step rise condition with and without additional phase-locked loop (PLL) freezing control, respectively, and with the present invention superimposed. Figures 6(e) and 6(f) show the active power response under a voltage drop condition with no frequency deviation, with and without additional phase-locked loop (PLL) freezing control, respectively, and with the present invention superimposed. Detailed Implementation
[0026] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.
[0027] This invention is an adaptive control method for phase-locked loop frequency reference of a grid converter. For example... Figure 4 As shown, the system targeted by this invention is a grid-connected system comprising multiple grid-connected converters. Each grid-connected converter is connected to a common coupling point via a filter, and then connected to the grid's Thevenin equivalent circuit via transmission lines. The overall execution flow of the method described in this invention is as follows: Figure 1 As shown, the specific block diagram of frequency reference adaptive control is as follows: Figure 3 As shown. The specific implementation steps of this method are as follows: Step 1: Real-time acquisition of three-phase voltage and current at the ports of the grid-connected converter, calculation and acquisition of the active power measurement value of the grid-connected converter. .like Figure 3 As shown, the active power deviation is illustrated. Feedback gain The processed value generates a frequency correction value, which is compared with the rated frequency reference value. The corrected frequency reference value is obtained by superposition. and replace the original rated frequency reference value. The signal flow of the input phase-locked loop control link will be... The data is preprocessed using a low-pass filter to remove the impact of measurement noise on subsequent calculations.
[0028] When the system contains multiple grid-connected converters The sum of the active power output of each grid-connected converter at the point of common coupling is obtained, and then transmitted to each grid-connected converter in the cluster via the station's communication bus. This is done when the system contains only a single grid-connected converter. The local output active power measurement value is directly obtained. All the above signals originate from the local control system of the grid-connected converter, without the need for a wide-area monitoring communication network, nor is it necessary to identify parameters such as grid impedance and system inertia.
[0029] Step 2: Use the steady-state value of active power before the fault occurs as the reference value for active power. , It can be recorded and saved during normal operation and remains unchanged after a fault occurs. Calculate the active power deviation: .
[0030] When the system contains multiple grid-connected converters The total active power reference value of the cluster is obtained and sent to each grid-type converter in the cluster via the station communication bus.
[0031] Step 3: Determine the feedback gain based on Lyapunov stability theory. The quantitative design lower bound ensures that the closed-loop system of the phase-locked loop frequency reference adaptive control of the grid converter satisfies local input state stability within the defined domain. Must meet: , In the formula, As the upper bound of the frequency deviation between the sending and receiving power grids, in actual engineering, it can be conservatively taken according to the upper limit of the allowable deviation range of system frequency specified in the power grid regulations. The Thevenin equivalent voltage amplitude on the grid side; The summation current amplitude is the resultant current amplitude after the vector superposition of the output current phasors of all grid-connected converters at the common coupling point. When the system contains only a single grid-connected converter, it degenerates into the local output current amplitude of that single grid-connected converter. To determine the power angle at the stable equilibrium point of the grid-connected system with the grid-connected converter, based on the power balance condition... Confirmed. The above conditions are met. The design conditions ensure that the steady-state error of the closed-loop system is limited to the domain. Within this system, local input state stability is satisfied.
[0032] Step 4: Refer to Figure 3 The feedback gain determined in step 3 The deviation Δ from the active power calculated in step 2 P The product of these two values serves as a correction factor for the phase-locked loop (PLL) frequency reference value. The phase-locked loop (PLL) frequency reference value is dynamically corrected to obtain the corrected frequency reference value. .like Figure 2 As shown, with Replace the original fixed rated PLL frequency reference value in the PLL control link When the grid frequency experiences a sustained shift, the active power deviation Δ P As it changes, Dynamically following the grid frequency eliminates the conflict between the fixed rated phase-locked loop frequency reference and the dynamic grid frequency at its source.
[0033] Step 5: Use the corrected PLL frequency reference value obtained in Step 4. Replaces the fixed rated frequency reference value of the phase-locked loop in traditional control. The frequency reference input is fed into the existing phase-locked loop (PLL) transient stability enhancement control scheme. Working in conjunction with this scheme, the corrected PLL phase is output, achieving transient synchronous stability enhancement for the grid-connected converter under combined fault disturbances such as pure voltage dips, pure frequency offsets, and both concurrently. The modification in this invention is limited to the frequency reference input of the PLL control link and does not affect the current control command generation stage. The internal structure and control logic of the existing control scheme remain unchanged. The superposition methods for the three existing PLL transient stability enhancement control schemes are as follows: a. When the existing solution is a phase-locked loop damped loop control, The frequency reference input terminal of the phase-locked loop damping loop control is fed into the phase-locked loop, and the parameters of the phase-locked loop proportional-integral controller and the damping feedback coefficient remain unchanged.
[0034] b. When the existing solution is phase-locked loop freeze control, The frequency reference input to the phase-locked loop (PLL) freeze control remains unchanged, as do the PLL freeze trigger logic and the angle holding mechanism during the freeze period.
[0035] c. When the existing solution is phase angle deviation compensation control, The frequency reference input terminal of the phase angle deviation compensation control is sent to the phase angle deviation compensation control, and the state feedback coefficient and other control logic of the phase angle deviation compensation control remain unchanged.
[0036] Example: To verify the effectiveness of this invention, a test system containing three grid-connected converters was built on an electromagnetic transient simulation platform for simulation verification. The composite fault scenario consisted of two superimposed disturbances: first, a voltage disturbance, where the grid voltage drops to 0.05 per unit and recovers after 200 milliseconds; second, a frequency disturbance, occurring simultaneously with the voltage drop, considering both gradual and step-type frequency shifts, with the frequency deviation persisting even after voltage recovery. This composite fault scenario was used to simulate severe disturbance conditions in actual power grids where voltage drops and frequency shifts occur concurrently.
[0037] Figures 5(a) and 5(b) show the dynamic response curves of active power before and after the phase-locked loop damping loop control is superimposed with the present invention, respectively; Figures 5(c) and 5(d) show the dynamic response curves of active power before and after the phase-locked loop freezing control is superimposed with the present invention, respectively; Figures 5(e) and 5(f) show the dynamic response curves of active power before and after the phase angle deviation compensation control is superimposed with the present invention, respectively. As can be seen from the figures, under the same combined fault conditions of voltage and frequency sag, after superimposing the present invention, the active power of the phase-locked loop damping loop control (Figures 5(a) and 5(b)), phase-locked loop freezing control (Figures 5(c) and 5(d)), and phase angle deviation compensation control (Figures 5(e) and 5(f)) all recover from the unstable state to a stable output, verifying the stability improvement effect of the present invention after being compatible with and superimposed with the three existing schemes.
[0038] Figures 6(a) and 6(b) show the active power response under a 5 Hz frequency step drop condition using PLL freeze control alone and with the addition of the present invention, respectively; Figures 6(c) and 6(d) show the active power response under a 3 Hz frequency step rise condition using PLL freeze control alone and with the addition of the present invention, respectively; Figures 6(e) and 6(f) show the active power response under a voltage drop condition with no frequency deviation, with and without additional control, and with and without PLL freeze control combined with the present invention, respectively. As shown in the figures: under the condition of a 5 Hz frequency step drop, the system becomes unstable when using PLL freeze control alone (Figure 6(a)), but recovers stability after adding the present invention (Figure 6(b)); under the condition of a 3 Hz frequency step increase, the system also becomes unstable when using PLL freeze control alone (Figure 6(c)), but recovers stability after adding the present invention (Figure 6(d)); under the condition of only voltage drop without frequency deviation, the system becomes unstable without additional control (Figure 6(e)), while the system remains stable after adding the present invention to the PLL freeze control (Figure 6(f)). The above results jointly verify the transient synchronization stability improvement effect of the present invention under severe step frequency disturbances, and the compatibility of combining the present invention with PLL freeze control under the condition of only voltage drop without affecting its original stability improvement effect.
Claims
1. A frequency reference adaptive control method for a grid-type converter with a phase-locked loop, characterized in that, Includes the following steps: Step 1: Real-time acquisition of three-phase voltage and current at the ports of the grid-connected converter, calculation and acquisition of the active power measurement value of the grid-connected converter. And it is processed by low-pass filtering; Step 2: Use the steady-state value of active power before the fault occurs as the reference value for active power. Calculate the active power deviation ; Step 3: Determine the feedback gain based on Lyapunov stability theory. The quantitative design lower bound ensures that the closed-loop system of the phase-locked loop frequency reference adaptive control of the grid converter satisfies local input state stability within the defined domain. Step 4: Using the feedback gain determined in Step 3 Deviation from the active power calculated in step 2 The product of these two values serves as a correction factor for the phase-locked loop (PLL) frequency reference value. The phase-locked loop (PLL) frequency reference value is dynamically corrected to obtain the corrected PLL frequency reference value. To replace the phase-locked loop frequency reference value ; Step 5: Use the corrected PLL frequency reference value obtained in Step 4. When applied to existing phase-locked loop transient stability enhancement control schemes, it works in conjunction with the existing phase-locked loop transient stability enhancement control schemes to output a corrected phase-locked loop phase, thereby achieving transient synchronous stability enhancement of grid-connected converters under combined fault disturbance conditions such as pure voltage drop, pure frequency offset, and both concurrently.
2. The adaptive control method for phase-locked loop frequency reference of a grid converter according to claim 1, characterized in that: In step 3, the feedback gain The lower bound of the quantitative design is jointly determined by the upper bound of the frequency deviation, the magnitude of the Thevenin equivalent voltage on the grid side, the magnitude of the combined current at the point of common coupling, and the power angle at the system's stable equilibrium point. Specifically: ， In the formula, It is the upper bound of the frequency deviation between the sending and receiving power grids; The Thevenin equivalent voltage amplitude on the grid side; The summation current amplitude is the resultant current amplitude after the vector superposition of the output current phasors of all grid-connected converters at the common coupling point. When the system contains only a single grid-connected converter, it degenerates into the local output current amplitude of that single grid-connected converter. To determine the power angle at the stable equilibrium point of the grid-connected system with the grid-connected converter, based on the power balance condition... Sure.
3. The adaptive control method for phase-locked loop frequency reference of a grid converter according to claim 1, characterized in that: In step 5, the existing phase-locked loop transient stability improvement control scheme is a phase-locked loop damping loop control; the modification to the phase-locked loop damping loop control is limited to fixing the rated phase-locked loop frequency reference value at its frequency reference input terminal. Replace with the corrected PLL frequency reference value obtained in step 4. The correction applies to the frequency reference input of the phase-locked loop control link, rather than to the current control command generation stage; the phase-locked loop proportional-integral controller parameters and other control logic remain unchanged.
4. The adaptive control method for phase-locked loop frequency reference of a grid converter according to claim 1, characterized in that: In step 5, the existing phase-locked loop transient stability improvement control scheme is phase-locked loop freeze control; the modification to phase-locked loop freeze control is limited to fixing the rated phase-locked loop frequency reference value at its frequency reference input terminal. Replace with the corrected PLL frequency reference value obtained in step 4. The correction applies to the frequency reference input of the phase-locked loop control link, rather than to the current control command generation stage; the phase-locked loop proportional-integral controller parameters and other control logic remain unchanged.
5. The adaptive control method for phase-locked loop frequency reference of a grid converter according to claim 1, characterized in that: In step 5, the existing phase-locked loop transient stability improvement control scheme is a control method that improves the transient stability of grid-connected converters by compensating for the dynamic deviation between the phase angle of the phase-locked loop output and the phase angle of the grid voltage through coordinate transformation. This is hereinafter referred to as phase angle deviation compensation control. The modification to phase angle deviation compensation control is limited to fixing the rated phase-locked loop frequency reference value at its frequency reference input. Replace with the corrected PLL frequency reference value obtained in step 4. The correction applies to the frequency reference input of the phase-locked loop control link, rather than to the current control command generation stage; the phase-locked loop proportional-integral controller parameters and other control logic remain unchanged.
6. The adaptive control method for phase-locked loop frequency reference of a grid converter according to claim 1, characterized in that: Active power measurement value in step 1 and the active power reference value in step 2 All of these originate from the local control system of the grid-connected converter, eliminating the need for a wide-area monitoring communication network and the identification of grid impedance and system inertia parameters. When the system contains multiple grid-connected converters Take the sum of the active power output of each grid-connected converter at the point of common coupling. The total active power reference value of the cluster is obtained, and both are acquired uniformly at the common connection point and then distributed to each grid-type converter within the cluster via the station's communication bus; when the system contains only a single grid-type converter... Directly retrieve the local output active power measurement value.