New energy cluster unified synchronous control method and system

Abstract

The new energy cluster unified synchronous control method and system generate a unified phase reference signal, distribute it to each power electronic converter, judge the operation mode of the power electronic converter, when in the normal mode, execute the next step, when in the communication fault mode, use the phase output by the local phase-locked loop as the coordinate transformation orientation basis, when the mode changes, adopt the set switching control strategy for transition; replace the phase output by the local phase-locked loop with the received unified phase reference signal as the coordinate transformation orientation basis, generate a unified rotating coordinate system; the power control link and the current control link of each power electronic converter generate a modulation wave signal, execute the grid-connected power unified synchronous control. The application reduces the multi-input multi-output coupling system to a decoupling system driven by a single phase reference, eliminates the mutual oscillation generated by the parallel connection of multiple machines, and improves the fault ride-through capability of the new energy cluster.

Description

Technical Field

[0001] This invention belongs to the field of power system operation and control technology, and more specifically, relates to a unified synchronization control method and system for new energy clusters. Background Technology

[0002] With the increasing integration of renewable energy into the grid, the stability issues of multiple inverters operating in parallel within renewable energy power plants are becoming increasingly prominent. Existing technologies mainly suffer from the following shortcomings: 1. In existing renewable energy power plants, each grid-connected inverter is equipped with an independent phase-locked loop (PLL) to track the grid phase. When N inverters are running in parallel, the system exhibits multi-input multi-output coupling characteristics. Each inverter independently adjusts its frequency and phase, which easily leads to high-order mutual oscillations, resulting in power circulating currents and wideband oscillations within the power plant, and mutual interference between multiple units.

[0003] 2. When a grid fault occurs or the voltage drops, each inverter relies on an independent phase-locked loop for phase tracking, which can easily lead to loss of synchronization. If one inverter loses synchronization and disconnects from the grid, it will cause grid voltage disturbances, which in turn will trigger a chain reaction of other inverters disconnecting from the grid, seriously affecting grid safety.

[0004] 3. Existing inverter grid-type control technology makes each inverter an independent voltage source and solves the stability problem caused by phase-locked loop by using power synchronization. However, the lack of unified coordination between voltage sources increases the complexity of the system and makes distributed grid-type control unreliable.

[0005] 4. Since each inverter is coupled to the other through the grid voltage, the system model is extremely complex for large-scale power plants containing dozens or even hundreds of inverters, making it difficult to perform stability analysis and parameter tuning.

[0006] Existing technical document 1 (CN118300184A) discloses a grid-connected control system and method for new energy and energy storage power plants. It generates current commands for each power generation unit through a grid-connected power plant control device. However, its shortcomings are: 1) Each inverter becomes an independent voltage source, forming a complex coupled system; 2) It is highly dependent on the grid-connected power plant control device as a comprehensive controller to generate power commands. The generator unit is only an execution unit and has no autonomy in power regulation. Once the control device experiences an internal fault or communication interruption, it will lead to the paralysis of the power plant; 3) It does not solve the problem of mutual oscillation among multiple PLLs. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a unified synchronization control method and system for new energy clusters, which solves the problems of high-order mutual oscillation, chain disconnection during faults, and complex and unreliable decentralized network control caused by distributed phase-locking at existing new energy power plants or collection stations.

[0008] The present invention adopts the following technical solution.

[0009] The first aspect of this invention provides a unified synchronization control method for a new energy cluster, wherein each new energy power generation unit and / or energy storage unit in the new energy cluster is grid-connected and controlled via a power electronic converter, comprising the following steps: Step 1: Generate a unified phase reference signal; Step 2: Distribute the unified phase reference signal to each power electronic converter in the new energy cluster, and simultaneously determine the operating mode of the power electronic converter. When it is in normal mode, execute step 3. When it is in communication failure mode, use the phase output of the local phase-locked loop as the coordinate transformation orientation basis. When the mode changes, the set switching control strategy is used for transition. Step 3: Replace the phase output of the local phase-locked loop with the received unified phase reference signal as the basis for coordinate transformation orientation to generate a unified rotating coordinate system; Step 4: The power control and current control links of each power electronic converter generate modulation wave signals based on a unified rotating coordinate system. The modulation wave signals are input to the modulation device to obtain switching drive signals. The power electronic converters perform grid-connected power unified synchronous control according to the switching drive signals.

[0010] Preferably, in step 1, the method for generating the unified phase reference signal includes: The generation can be based on the voltage phase-locked loop of the high-voltage main grid into which the new energy cluster is connected, the generation can be based on the rotor position signal of the synchronous machine, or the self-synchronization generation can be based on the virtual synchronous machine algorithm.

[0011] Preferably, the generation of a unified phase reference signal based on the voltage phase-locked loop of the high-voltage main grid into which the new energy cluster is connected includes the following steps: The voltage signal is collected from the high-voltage bus voltage or the three-phase voltage signal at the grid connection point of the new energy cluster, and the voltage signal is generated through coordinate transformation. q Axial components; A phase-locked loop (PLL) structure is adopted, and the voltage of the high-voltage side bus or the grid connection point is set. q The reference value for the axis component is 0, and the phase output by the phase-locked loop at this time is used as the unified phase reference signal. i ref It can be expressed by the following formula:

[0012]

[0013] In the formula, oh ref To unify the angular frequency reference signal, oh g0 The rated angular frequency, and These are the proportional and integral gains of the phase-locked loop, respectively. v gq The voltage of the high-voltage side bus or the voltage at the grid connection point. q Axial components.

[0014] Preferably, generating a unified phase reference signal based on the synchronous machine rotor position signal includes the following steps: The mechanical position signal of the synchronous machine rotor connected to the same high-voltage busbar as the new energy cluster is collected. Based on the number of pole pairs of the synchronous machine, the mechanical angle is converted into an electrical angle as a unified phase reference signal. i ref It can be expressed by the following formula:

[0015] In the formula, p Let be the number of pole pairs of the synchronous machine. i m This is the mechanical position signal of the rotor. i 0 represents the initial phase compensation angle.

[0016] Preferably, for synchronous machines without or unable to install rotor position measuring devices, a unified phase reference signal is generated by using the phase-locked angle of the three-phase transient internal potential to replace the rotor position signal, including the following steps: Calculate static α - β The transient internal potential in the coordinate system is expressed by the following formula:

[0017] In the formula, , These are the transient internal potentials. α Axial components, β Axial components, , These are the output voltages of the synchronous machine. α Axial components, β Axial components, , These are the output currents of the synchronous machine. α Axial components, β Axial components, The equivalent resistance of the stator of the synchronous machine. The transient reactance of the synchronous machine; For static α - β The transient internal potential in the coordinate system is transformed inversely to obtain the three-phase transient internal potential. Phase-locking is then performed on the three-phase transient internal potential to obtain a unified phase reference signal. i ref .

[0018] Preferably, the self-synchronization generation of a unified phase reference signal based on the virtual synchronizer algorithm includes the following steps: A virtual rotor motion equation is constructed, and a unified phase reference signal is generated using the virtual angular frequency integral in the virtual rotor motion equation. i ref .

[0019] Preferably, in step 2, the methods for determining the operating mode of the power electronic converter include: heartbeat packet timeout detection, phase frequency validity verification, and communication quality monitoring; when a communication fault is detected by any of these methods, the power electronic converter is considered to be in a communication fault mode, and when no communication fault is detected by any of these methods, the power electronic converter is considered to be in a normal mode.

[0020] Preferably, the heartbeat timeout detection includes: every set period of time. T hb Send heartbeat packets to each power electronic converter; if the power electronic converter is in 3... T hb If no heartbeat packet is received within a certain time, the communication is considered interrupted.

[0021] Preferably, the phase frequency validity verification includes: constructing a phase continuity verification mechanism and an angular frequency range verification mechanism, and determining a communication failure when either validity verification is not met; The phase continuity verification mechanism is expressed by the following formula:

[0022] In the formula, , They are respectively the first k sequence k -1 unified phase reference signal sent out, The set transition threshold; The angular frequency range verification mechanism is expressed by the following formula:

[0023] In the formula, oh ref To unify the angular frequency reference signal, oh g0 The rated angular frequency, This is the angular frequency threshold.

[0024] Preferably, the communication quality monitoring includes: real-time monitoring of communication latency and packet loss rate; when the communication latency is greater than a set communication latency threshold or the packet loss rate is greater than a set packet loss rate threshold, a communication fault is determined and a pre-alarm is triggered.

[0025] Preferably, in step 2, the switching control strategy includes: When the power electronic converter switches from normal mode to communication fault mode, the phase difference at the current moment is calculated, and a slow-release compensation strategy is adopted during the set switching transition time. The transition phase is used as the basis for coordinate transformation orientation. When the power electronic converter switches back from communication fault mode to normal mode, it calculates the real-time phase difference, generates angular frequency compensation, injects the angular frequency compensation into the integrator of the local phase-locked loop, obtains the compensated phase, and performs synchronization between the local phase and the remote phase until the absolute value of the real-time phase difference is less than the set phase difference threshold and remains so for a set time, at which point synchronization is considered complete.

[0026] Preferably, when the power electronic converter switches from normal mode to communication fault mode, the transition phase is calculated using the following formula:

[0027]

[0028] In the formula, i trans ( t () represents the transition phase. for t The phase of the local phase-locked loop output at any given time, Δ i 0 represents the initial phase difference. t 0 represents the switching trigger time. T trans To switch the transition duration, To switch the phase of the local phase-locked loop output at the trigger time, This refers to the unified phase reference signal received by the power electronic converter at the switching trigger moment.

[0029] Preferably, when the power electronic converter switches back from communication failure mode to normal mode, the compensated phase is calculated using the following formula:

[0030]

[0031]

[0032] In the formula, The compensated phase, The angular frequency of the local phase-locked loop integrator is [value]. This is the angular frequency compensation amount. and These are the proportional and integral gains of the PI controller, respectively. For real-time phase difference, fort The phase of the local phase-locked loop output at any given time. for t The unified phase reference signal received by the power electronic converter at any given time.

[0033] Preferably, in step 3, generating a unified rotating coordinate system based on the coordinate transformation orientation includes: All power electronic converters in normal mode use a unified phase reference signal. i ref As the rotation angle of the Park transform, the unified orientation d - q Coordinate system.

[0034] Preferably, step 4 includes: Step 4.1: Construct the power control loop for each power electronic converter based on a unified rotating coordinate system. The active power is autonomously adjusted according to the input status of the primary energy source or the upper-level dispatch command, while the reactive power is coordinated and controlled according to the voltage command of the new energy cluster. Step 4.2: Based on the power control loop, construct a power loop control model in a unified rotating coordinate system, and calculate the current loop reference value through the power outer loop and instantaneous power theory. Step 4.3: Construct the current control loop for each power electronic converter, perform closed-loop current control based on the current loop reference value, and after inductor voltage decoupling and grid voltage feedforward, generate three-phase switch modulation wave signals based on a unified rotating coordinate system using inverse Park transformation. Step 4.4: Generate a switch drive signal based on the modulation wave signal of the three-phase switch tubes to control the switching of the power electronic converter.

[0035] Preferably, while performing active power control, each power electronic converter activates a positive damping generation module to generate an additional damping power command by utilizing the change in angular velocity difference between the local backup phase-locked loop and the remote unified phase reference, which is then superimposed on the original active power command.

[0036] Preferably, a reactive power command is generated based on the voltage control command issued by the synchronization control module, expressed by the following formula:

[0037]

[0038] In the formula, Q ref This is a reactive power command. This is the original reactive power instruction. This is the reactive power regulation coefficient. This is a reference value for the inverter output voltage amplitude. This is a measured value of the actual output voltage amplitude of the power electronic converter. v od and v oq These are the AC output voltages of the power electronic converter. d shaft and q Axial components.

[0039] Preferably, the power loop control model in a unified rotating coordinate system is expressed by the following formula:

[0040] In the formula, P ref and Q ref These are the active power and reactive power command values ​​that the AC side of the power electronic converter exchanges with external systems. v od and v oq These are the AC output voltages of the power electronic converter. d shaft and q Axial components, i Ldref and i Lqref These are the reference values ​​for the AC output current of the power electronic converter. d shaft and q Axial components.

[0041] Preferably, the frequency domain equation for the current closed-loop control is as follows:

[0042] In the formula, v mdref and v mqref These are the modulation wave signals generated by the current control circuit. d shaft and q Axial components, k pi and k ii These are the P and I parameters of the current loop, respectively. i Ld and i Lq These are the AC side inductor currents of the power electronic converter. d shaft and q Axial components, oh The angular frequency of the AC output current of the power electronic converter. L For the AC side inductance of the power electronic converter, v od and voq These are the AC output voltages of the power electronic converter. d shaft and q Axial components.

[0043] A second aspect of the present invention provides a unified synchronization control system for new energy clusters, based on the aforementioned unified synchronization control method for new energy clusters, comprising: Synchronization control module, used to generate a unified phase reference signal; A communication network is used to connect the synchronization control module and the power electronic converter, and to transmit a unified phase reference signal; The controller for multiple power electronic converters includes a signal receiving module, a communication fault detection module, a orientation data generation module, a unified coordinate generation module, a coordinate transformation module, a power control loop, and a current control loop, wherein: The signal receiving module is used to receive a unified phase reference signal through the communication network; The communication fault detection module is used to determine whether the power electronic converter is in normal mode or communication fault mode. The orientation reference generation module is used to directly use the unified phase reference signal as the orientation reference for coordinate transformation when the communication fault detection module outputs the normal mode, and to use the phase output by the local phase-locked loop as the orientation reference for coordinate transformation when the communication fault detection module outputs the communication fault mode. The unified coordinate generation module is used to generate a unified rotating coordinate system based on the coordinate transformation orientation criteria; The coordinate transformation module is used to perform coordinate transformation and inverse coordinate transformation on the input and output of the power control and current control loops based on a unified rotating coordinate system. The power control and current control circuits are used to perform unified synchronous control of grid-connected power.

[0044] Preferably, the synchronization control module includes any of the following units: The voltage measurement and phase-locked loop unit is used to collect the voltage of the high-voltage main grid into which the new energy cluster is connected and extract phase information; Synchronous machine interface unit, used to acquire and process the rotor position signal of the synchronous machine; The virtual synchronizer generation unit is used to generate phase signals based on the virtual rotor motion equations.

[0045] Preferably, the power control circuit of each power electronic converter autonomously determines the active power command based on the input status of the primary energy source or the upper-level dispatch command, and determines the reactive power command based on the voltage control command issued by the synchronization control module.

[0046] A third aspect of the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the new energy cluster unified synchronization control method.

[0047] A fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the aforementioned unified synchronization control method for new energy clusters.

[0048] Compared with the prior art, the beneficial effects of the present invention include at least the following: 1. The unified synchronization control method and system for new energy clusters of the present invention replaces the independent phase-locked loops of each converter with a unified phase reference signal, realizing the synchronization of coordinate transformation. This physically reduces the multi-input multi-output coupled system to a decoupled system driven by a single phase reference, achieving decoupling between units and significantly simplifying the system model. Even with differences in line impedance, there will be no power oscillations caused by mutual interference, fundamentally eliminating mutual oscillations caused by multiple units in parallel, and significantly improving the small-disturbance stability of the new energy cluster under weak power grid conditions.

[0049] 2. In the event of a grid fault or voltage drop, the unified synchronization control method and system for new energy clusters of the present invention maintains the continuity of a unified phase reference at the new energy cluster level, and each inverter maintains the consistency of coordinate transformation based on the continuous phase reference. Even if individual units are disconnected due to faults, it will not cause other units to disconnect from the grid through phase disturbances, significantly improving the fault ride-through capability of the new energy cluster.

[0050] 3. When adding a new inverter, the unified synchronization control method and system for new energy clusters of the present invention only needs to connect to a unified phase reference signal to automatically synchronize with the existing system, without the need for complex parameter coordination. As the scale of the power station expands, the complexity of the system synchronization link does not increase, and the stability is not affected. It can be further extended to new energy aggregation stations, providing a unified phase reference for multiple geographically dispersed new energy clusters, achieving wider-range synchronization and coordination control, and improving the stability of the regional power grid.

[0051] 4. The unified synchronization control method and system for new energy clusters of the present invention makes the new energy cluster equivalent to a single control unit in terms of external characteristics. The power grid dispatching agency can dispatch the entire new energy cluster in the same way as dispatching a traditional synchronous generator, which simplifies the complexity of power grid dispatching. Attached Figure Description

[0052] Figure 1 This is a flowchart of a unified synchronization control method for new energy clusters provided in accordance with an embodiment of the present invention; Figure 2This is a schematic diagram of a synchronization control architecture that uses a synchronous machine to generate a unified phase reference signal based on the three-phase transient internal potential of a synchronous machine, according to an embodiment of the present invention. Figure 3 This is a control block diagram of a bidirectional T-type three-level converter PQ according to an embodiment of the present invention; Figure 4 This is a block diagram of a single synchronous coordinate system software phase-locked loop control provided in accordance with an embodiment of the present invention; Figure 5 This is a schematic diagram of the equivalent control model of the current loop provided in accordance with an embodiment of the present invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0054] like Figure 1 As shown, Embodiment 1 of the present invention provides a unified synchronization control method for new energy clusters. This method is applicable to new energy power plants such as photovoltaic power plants, direct-drive wind farms, and energy storage power plants that use power electronic converters for grid connection. It is also applicable to new energy aggregation stations that aggregate multiple geographically dispersed new energy power plants. The new energy cluster includes new energy power generation units and / or energy storage units, and the power electronic converter includes photovoltaic inverters, direct-drive wind power converters, or energy storage converters. The following description uses an application scenario of a new energy power plant as an example. The method includes the following steps: Step 1: Generate a unified phase reference signal at the field station level. It serves as a unified rotation angle reference for coordinate transformation of the power electronic converters corresponding to all new energy power generation units in the entire station.

[0055] In a preferred but non-limiting embodiment of the present invention, a station-level synchronization control unit (SSCU) generates a unified phase reference signal. The generation methods include: generation based on high-voltage main grid voltage phase-locked loop, generation based on synchronous machine rotor position signal, or self-synchronization generation based on virtual synchronous machine algorithm. The synchronous machine includes synchronous condenser and synchronous generator, which are connected to the same high-voltage side bus with each new energy power generation unit and energy storage unit of the station.

[0056] More preferably, generating a unified phase reference signal based on the voltage phase-locked loop of the high-voltage main grid connected to the substation includes the following steps: Step A.1: Collect the three-phase voltage signal from the high-voltage side busbar or point of common coupling (PCC) of the power station. v gabc ( t The high-voltage side bus voltage or PCC voltage is generated through coordinate transformation. d Axial components and q Axial components.

[0057] Step A.2: Using a PLL structure, set the high-voltage side bus voltage or PCC voltage. q Axial components v gq The reference value is 0, and the angular frequency output by the PLL at this time is... oh g As a unified angular frequency reference signal oh ref Phase of PLL output i g As a unified phase reference signal i ref It can be expressed by the following formula:

[0058]

[0059] In the formula, oh ref To unify the angular frequency reference signal, oh g0 The rated angular frequency, and These are the proportional and integral gains of the PLL, respectively.

[0060] More preferably, generating a unified phase reference signal based on the synchronous machine rotor position signal includes the following steps: Step B: Acquire the mechanical position signal of the rotor of the synchronous machine in the field. i m According to the number of pole pairs of the synchronous machine p The mechanical angle is converted into an electrical angle as a unified phase reference signal. i ref It can be expressed by the following formula:

[0061] In the formula, i m This is the mechanical position signal of the rotor, which can be measured by devices such as encoders and rotary transformers. i 0 is the initial phase compensation angle, used to calibrate the initial offset between the rotor position and the grid voltage phase.

[0062] More preferably, for synchronous machines that do not have or cannot be equipped with rotor position measuring devices, the transient internal potential of the three phases during the transient process is taken into account. of q The axial components remain unchanged and d The shaft component is small and negligible; the three-phase transient internal potential is used. The phase-locked angle is used to replace the rotor position signal to generate a unified phase reference signal. i ref ,like Figure 2 The synchronous control architecture shown includes the following steps: Step C.1: Replace the differential element with a vector rotation to reduce the disturbance introduced by the differential element, and calculate the static state. α - β Transient internal potential in coordinate system It can be expressed by the following formula:

[0063] In the formula, , These are the output voltages of the synchronous machine. α Axial components, β Axial components, , These are the output currents of the synchronous machine. α Axial components, β Axial components, For the transient reactance of the synchronous machine, R This is the equivalent resistance of the stator of the synchronous machine.

[0064] Step C.2, for the stationary state α - β Transient internal potential in coordinate system Perform an inverse coordinate transformation to obtain the three-phase transient internal potential. Refer to steps A.1-A.2 to assess the three-phase transient internal potential. Phase-locked loop (PLL) is used to obtain a unified phase reference signal. i ref .

[0065] It is understood that this invention uses the phase-locked angle of the three-phase transient internal potential during the transient process to replace the rotor angle, and generates a unified phase reference signal. i ref It can provide a stable phase reference during a fault.

[0066] According to the rotor motion equations of a synchronous machine, when a voltage drop occurs due to a symmetrical or asymmetrical fault in the power grid, although the electromagnetic torque will change transiently, the rotor's rotational speed will not change abruptly due to its large moment of inertia, but will change slowly according to the rotor motion equations. Therefore, the unified phase reference signal determined by the rotor position... i ref It can maintain continuous and stable rotation during faults, and is not affected by grid voltage distortion, phase jump or harmonic interference, providing a stable phase reference for each power electronic converter in the station and avoiding phase loss due to abnormal grid voltage.

[0067] More preferably, based on the Virtual Synchronous Generator (VSG) algorithm, a unified phase reference signal is generated through self-synchronization by simulating the rotor motion equation of a synchronous generator, including the following steps: Step D.1: Construct the motion equations of the virtual rotor, expressed as follows:

[0068] In the formula, J v For virtual inertia, D v This is the virtual damping coefficient. P set This is the active power setpoint. P e To measure the active power, oh v For virtual angular frequency, oh g0 This is the rated angular frequency.

[0069] Step D.2: Use the virtual angular frequency integral in the virtual rotor motion equation to generate a unified phase reference signal. i ref It can be expressed by the following formula:

[0070] Understandably, the VSG algorithm generates a unified phase reference signal. i ref Without the need for a physical synchronizer, it simulates inertia characteristics through software algorithms, providing a phase reference with inertia support even during faults.

[0071] It is worth noting that those skilled in the art can also use the phase obtained by conventional algorithms in the prior art as a unified phase reference signal, and all of these fall within the protection scope of the present invention in accordance with the spirit of the present invention.

[0072] Step 2: Distribute the unified phase reference signal to all power electronic converters in the station through the communication network, and simultaneously determine the operating mode of the power electronic converters. When in normal mode, execute step 3; when in communication failure mode, use the phase output of the local phase-locked loop as the coordinate transformation orientation basis; when the mode changes, use the set switching control strategy to transition between normal mode and communication failure mode.

[0073] In a preferred but non-limiting embodiment of the present invention, a unified phase reference signal is distributed in real time to each power electronic converter in the site via optical fiber, 5G, or other high-speed communication methods. After receiving the unified phase reference signal, each power electronic converter cancels its internal PLL calculation function, no longer independently performs phase tracking based on local voltage measurements, and adds a multi-mode smooth switching control strategy to achieve seamless switching between normal mode and communication failure mode. Step 2 specifically includes: Step 2.1: Construct a communication fault detection mechanism and configure multi-dimensional fault detection criteria to ensure timely identification of communication anomalies. When any one of the fault detection criteria is met, a communication fault is determined to have occurred, and the power electronic converter switches to the communication fault mode; otherwise, it continues to operate in normal mode. The communication fault detection mechanism includes: heartbeat packet timeout detection, phase and frequency validity verification, and communication quality monitoring.

[0074] In a further preferred but non-limiting embodiment of the present invention, step 2.1 specifically includes: Step 2.1.1, the station-level synchronization control module performs this every set period. T hb Send heartbeat packets to each power electronic converter; if the power electronic converter is in 3... T hb If no heartbeat packet is received within a certain time, the communication is considered interrupted.

[0075] More preferably, the heartbeat packet sending period T hb Set to 10 50ms.

[0076] Step 2.1.2: Construct a phase continuity verification mechanism and an angular frequency range verification mechanism to verify the issued unified phase reference signal. i ref The validity of the signal is determined by checking the validity of any phase frequency. If the validity of any phase frequency is not met, the communication is considered to be faulty. The phase continuity check is used to prevent the uniform phase reference signal from jumping, and the angular frequency range check is used to prevent abnormal frequency interference.

[0077] More preferably, the phase continuity verification mechanism is expressed by the following formula:

[0078] In the formula, , They are respectively the first k sequence k -1 unified phase reference signal sent out, This is the set phase transition threshold.

[0079] More preferably, the angular frequency range verification mechanism is expressed by the following formula:

[0080] In the formula, The angular frequency threshold can be set based on empirical values. In an exemplary but non-limiting embodiment of the present invention, the corresponding angular frequency of 6πrad / s for a frequency of 3Hz is taken as the angular frequency threshold.

[0081] Step 2.1.3, Real-time monitoring of communication latency t and packet loss rate P loss ,when t > t th or P loss > P lossth A communication failure is detected in time, triggering a pre-alarm.

[0082] More preferably, the communication delay threshold t th Set to 50ms, packet loss rate threshold P los Set to 5%.

[0083] Step 2.2: Establish the generation strategy for coordinate transformation orientation of the power electronic converter in normal mode and communication fault mode respectively. All power electronic converters simultaneously execute the corresponding generation strategy according to the mode identified in Step 2.1. Specifically: When in normal mode, a remote synchronization strategy is executed, using a unified phase reference signal issued at the field station level. i ref As the basis for coordinate transformation orientation; bypass the local PLL to put it in hot standby state, continuously track but do not output control; the positive damping generation module in step 4.1 is enabled, and positive damping is generated by using the difference between the remote and local angular velocities.

[0084] More preferably, the complete bypass of the local PLL is achieved in the following manner: Upon receiving the unified phase reference signal, each power electronic converter disables or bypasses its internal software PLL module; disables the frequency tracking algorithm in the frequency regulation stage; and transmits the received signal. i ref The value is directly assigned to the rotation angle input of the Park transformation module.

[0085] When in communication failure mode, the local autonomy strategy is executed, using the phase output by the local PLL. i local As the basis for coordinate transformation orientation; each transformer operates independently and performs coordinate transformation based on the local PLL; the positive damping generation module in step 4.1 is automatically disabled due to the failure of the distant signal.

[0086] Step 2.3 adds a transition phase to the switching between normal mode and communication fault mode of the power electronic converter, and adopts a smooth switching control strategy in the transition phase.

[0087] More preferably, to avoid current surges and power oscillations caused by phase jumps during mode switching, a phase difference closed-loop feedback and slow-release compensation are used to achieve a smooth transition. Step 2.3 specifically includes: Step 2.3.1, when the power electronic converter switches from normal mode to communication fault mode, the switching trigger time... t 0. The phase difference mitigation compensation strategy is implemented from the beginning, specifically: When a communication fault is detected, the power electronic converter switches from normal mode to communication fault mode, without immediately switching to the phase output of the local PLL. i local Instead, it first calculates the switching trigger time. t The initial phase difference Δ to 0 i 0 is represented by the following formula:

[0088] In the formula, To switch the phase of the local PLL output at the trigger time, This refers to the unified phase reference signal received by the power electronic converter at the switching trigger moment.

[0089] The set transition time T trans Internally, a slow-release compensation strategy is adopted, using a transition phase. i trans ( t As the basis for coordinate transformation orientation, it is expressed by the following formula:

[0090] In the formula, Δ i 0 represents the initial phase difference. t 0 represents the switching trigger time. T trans To switch the transition duration.

[0091] when t = t 0+ T trans hour, i trans = i local This completes a smooth transition, after which the local PLL is used entirely.

[0092] More preferably, the transition duration is changed. T trans Set to 100 500ms.

[0093] Step 2.3.2: When the power electronic converter switches from communication failure mode to normal mode, a synchronization switchback is performed after communication is restored. Specifically: Once communication is restored, the power electronic converter switches back from communication failure mode to normal mode. If a direct switch is performed at this point, it may cause issues with the unified phase reference signal. i ref Phase with local PLL output i local The existence of accumulated phase difference can lead to shocks; therefore, a phase pre-synchronization strategy is adopted to calculate the real-time phase difference. The angular frequency compensation amount Δ is generated by the PI controller. oh sync It can be expressed by the following formula:

[0094] In the formula, Δ oh sync This is the angular frequency compensation amount. and These are the proportional and integral gains of the PI controller, respectively. This represents the real-time phase difference.

[0095] Angular frequency compensation Δ oh sync The integrator stage of the local PLL is injected to obtain the compensated phase. This makes the phase output of the local PLL... i local Gradually track the unified phase reference signal i ref This achieves synchronization between the local and distant phases, and the compensated phase is expressed by the following formula:

[0096] In the formula, The compensated phase, ω is the angular frequency of the local phase-locked loop integrator.

[0097] During synchronization, if the absolute value of the real-time phase difference is |Δ i ( t )∣< e And after a certain period of time, it is determined that the synchronization is completed.

[0098] More preferably, the phase difference threshold e Set to 0.01 0.05 rad.

[0099] The synchronization process employs a gradual compensation strategy similar to that in step 2.3.1, adjusting the coordinate transformation orientation based on the compensated phase. i local Smooth transition to unified phase reference signal i ref After the transition is complete, it will officially enter normal mode.

[0100] It is worth noting that, apart from communication failures, when switching control strategies, such as from direct substitution control to a composite phase-locked loop control strategy, the phase angle difference feedback mechanism is also used. Specifically, this includes: before switching, calculating the phase command difference Δ under the two strategies. i strategy During the switching process, Δ is controlled by a first-order inertial element or a ramp function. i strategy Perform a soft transition to avoid abrupt changes in control variables; after the switch, fully enable the new strategy.

[0101] It is understood that the present invention proposes a multi-mode smooth switching control based on phase angle difference feedback to achieve a seamless transition between normal mode and communication failure mode, and to ensure the continuous and stable operation of the system during communication failure, extreme power grid conditions or control strategy switching.

[0102] Step 3: Bypass the local phase-locked loop and replace the phase output of the local phase-locked loop with the received unified phase reference signal as the coordinate transformation orientation basis. Generate a unified rotating coordinate system based on the coordinate transformation orientation basis.

[0103] In a preferred but non-limiting embodiment of the present invention, let the first... i The three-phase current of the power electronic converter is i a,i , i b,i 、i c,i The three-phase voltage is u a,i 、u b,i 、u c,i All power electronic converters in normal mode use a unified phase reference signal issued at the field station level. i ref As the rotation angle required for all Park transformations or similar coordinate transformations, all three-phase currents and three-phase voltages are transformed and placed in the same position. d - q In a coordinate system or a similar rotating coordinate system, to achieve d - q Unified orientation of a coordinate system or a similar rotating coordinate system.

[0104] Understandably, in existing technologies, each converter tracks the grid voltage phase using an independent PLL. Due to differences in line impedance, measurement errors, and PLL dynamic response, the estimated phase varies among converters, leading to discrepancies in the phase estimates of each converter. dq The coordinate systems are not truly synchronously rotating, and there is a relative angular difference. However, in this invention, in normal mode, all converters share the same phase reference, and the rotating coordinate systems of the entire site are strictly synchronized with zero phase difference. d shaft and q The axes have a strictly consistent physical orientation. This consistency allows the current vectors output by each converter to have a directly superimposed physical meaning in a unified coordinate system, eliminating control coupling caused by inconsistent coordinate system orientation.

[0105] Step 4: Based on a unified rotating coordinate system, each power electronic converter performs coordinate transformation on the inputs of the power control loop and the current control loop, and performs inverse coordinate transformation on the output of the current control loop to generate a modulation wave signal. The modulation wave signal is input to the modulation device to obtain a switch drive signal. The power electronic converter performs grid-connected power unified synchronous control according to the switch drive signal.

[0106] In a preferred but non-limiting embodiment of the present invention, step 4 specifically includes: Step 4.1: Construct the power control loop for each power electronic converter based on a unified rotating coordinate system. Specifically, as shown in... Figure 3 Taking the grid-connected PQ control strategy of the bidirectional T-type three-level converter as an example, the power control link is explained. The active power is autonomously adjusted according to the input status of the primary energy source, such as light intensity and wind speed, or the upper-level dispatch command, and is not constrained by the unified phase reference. The reactive power is coordinated and controlled according to the station-level voltage command.

[0107] In a further preferred but non-limiting embodiment of the present invention, under a synchronous control architecture based on a unified phase reference, each power electronic converter, while performing power control, enables a positive damping generation module to generate an additional damping power command by utilizing the change in angular velocity difference between the local backup PLL and the remote unified phase reference. This command is then superimposed onto the active power control loop to suppress possible low-frequency oscillations and improve the system's ability to suppress oscillations caused by small disturbances.

[0108] Although each converter uses a remotely unified phase reference during normal operation i ref As the primary control reference, each converter retains a local PLL as a backup synchronization reference for monitoring the local power grid phase. i local By calculating the rate of change of the angular velocity difference between the distant unified phase and the local phase in real time, a positive damping torque is generated. Step 4.1 specifically includes the following steps: Step 4.1.1: Obtain the unified angular frequency reference signal oh ref It is obtained by differential calculation from the station-level synchronous control module, and is expressed by the following formula:

[0109] Step 4.1.2: Estimate the angular velocity output by the local backup PLL in real time. oh local It can be expressed by the following formula:

[0110] in, oh 0 is the rated angular frequency, Δ oh PLL Output the deviation of the local PLL in tracking the power grid frequency.

[0111] Step 4.1.3, calculate the angular velocity deviation Δ between the local and distant phases. oh It can be expressed by the following formula:

[0112] Step 4.1.4: Obtain the rate of change by differentiating the angular velocity difference. and multiplied by the damping coefficient D damp Generate additional damping power command P damp It can be expressed by the following formula:

[0113] In the formula, D damp This is the damping coefficient, which is tuned based on system stability analysis and impedance scan results, and typically ranges from 0.1. 5.0 pu·s / rad.

[0114] Step 4.1.4: Add the additional damping power command to the original autonomous active power command. P ref This forms the final active power command. Ptotal It can be expressed by the following formula:

[0115] Understandably, by constructing positive damping, when the system is subjected to small disturbances such as load fluctuations or grid frequency disturbances: If the local rotational speed shows an upward trend, that is And when the change in rotational speed is greater than that at a distance, then Generate positive P damp Increase active power output and use the deceleration characteristics of rotor or virtual inertia to suppress speed increase; If the local rotational speed shows a decreasing trend, that is When, then a negative value is generated. P damp This reduces active power output and suppresses speed drop.

[0116] By introducing damping power proportional to the rate of change of angular velocity, an additional positive damping torque is provided to the system, further suppressing the mutual oscillation between units caused by non-phase-locked loop factors.

[0117] It is worth noting that this positive damping generation mechanism is fully compatible with the synchronous control architecture of the unified phase reference: Under normal operating conditions, the distant phase reference i ref It still serves as the basis for the main coordinate transformation, while the local PLL is only used for monitoring and does not participate in the main control loop; When generating damping, the change in angular velocity difference, i.e., the differential term, is used instead of the absolute phase difference. Therefore, the continuous power shift will not be caused by steady-state frequency deviation. During the transient process of power grid disturbance, the remote unified phase is maintained stable by the station-level synchronization control module, and its rotational speed changes... It reflects the overall inertia characteristics of the station, while This reflects the local unit response, and the difference between the two reflects the oscillation mode that needs to be damped and suppressed.

[0118] Step 4.1.5: According to the voltage control command issued by the synchronization control module Generate reactive power command Q ref It can be expressed by the following formula:

[0119] In the formula: These are the original reactive power commands, issued by the power station or set by the generator unit itself; This is the reactive power regulation coefficient; This is a reference value for the inverter output voltage amplitude, i.e., a voltage control command; The measured value of the actual output voltage amplitude of the power electronic converter is calculated using the following formula:

[0120] In the formula, v od and v oq The AC output voltage of the power electronic converter is respectively in the unified rotating coordinate system in step 3. d shaft and q Axial components.

[0121] Step 4.2, considering AC side voltage clamping, and under PQ grid control, maintaining constant output power by controlling the grid-connected current, a power loop control model in a unified rotating coordinate system is constructed. Then, using the power outer loop and instantaneous power theory, the current loop reference value is calculated, expressed by the following formula:

[0122] In the formula: P ref and Q ref These are the active power and reactive power command values ​​that the AC side of the power electronic converter interacts with externally. i Ldref and i Lqref These are the reference values ​​for the AC output current of the power electronic converter. d shaft and q Axial component, i.e., current loop reference value d shaft and q Axial components.

[0123] More preferably, the active and reactive power command values ​​of the power electronic converter are obtained by receiving dispatch commands from the power grid or by receiving MPPT controller outputs from new energy sources such as photovoltaic and wind power.

[0124] Step 4.3: Construct the current control loop for each power electronic converter. Based on the current loop reference value, a PI controller is used for closed-loop current control. After inductor voltage decoupling and grid voltage feedforward, an inverse Park transformation is performed based on a unified rotating coordinate system to generate the modulation wave signal of the three-phase switching transistors. v m ,like Figure 3 As shown, the frequency domain equation for the current closed-loop control is:

[0125] In the formula: v mdref and v mqref These are the modulation wave signals generated by the current control circuit. d shaft and q Axial components; k pi and k ii These are the P and I parameters of the current loop, respectively; i Ld and i Lq These are the AC side inductor currents of the power electronic converter. d shaft and q Axial components; oh The angular frequency of the AC output current of the power electronic converter; L This is the AC side inductor of the power electronic converter.

[0126] In a further preferred but non-limiting embodiment of the present invention, the PI controller stability analysis and parameter design include the following steps: Step E.1: Construct the PLL control model under a unified rotating coordinate system. Specifically, taking a single-synchronous coordinate system software PLL as an example, the control block diagram is as follows: Figure 4 As shown. Figure 4 In the middle, the grid voltage q Axial components v gq The difference from the zero reference is fed into the PI controller. Due to the PI controller's zero steady-state error regulation characteristic for DC quantities, it can adjust the grid voltage. q Axial components v gq The phase-locked loop approaches 0, thus completing the phase-locking process.

[0127] More preferably, the output of the PI controller is fed with the rated angular frequency. As a feedforward quantity, the system angular frequency is obtained. oh g Then integrate to obtain the phase. i g As the reference angle for the abc / dq coordinate transformation, it is fed back to v gq The calculation points are used to form a closed-loop control. Among them, f g0 The frequency of the connected power grid is used as the known center frequency to accelerate system coupling.

[0128] Step E.2: Calculate the closed-loop transfer function of the equivalent current loop after decoupling the control model. Specifically, after... Figure 3 The inductor voltage decoupling and grid voltage feedforward link shown in the figure have current... d , q Decoupling and feedforward cancellation have been achieved between the axes, resulting in an equivalent current loop after processing. i L Control structure such as Figure 5 As shown, the closed-loop transfer function is expressed by the following formula:

[0129] In the formula, k pi and k ii These are the P and I parameters of the current loop, respectively. k PWM This is a proportional element that approximates pulse width modulation. L f This is the equivalent inductance on the AC side of the converter. R This is the parasitic resistance on the AC side of the converter.

[0130] Step E.3: Based on the closed-loop transfer function of the equivalent current loop, and following the second-order system tuning method, set the damping ratio and solve for the corresponding PI controller parameters.

[0131] In one exemplary but non-limiting embodiment of the invention, the damping ratio is taken as... The undamped natural oscillation angular frequency is less than 1 / 10 of the switching angular frequency.

[0132] Step 4.4: Input the modulation wave signal of the three-phase switching transistor to the PWM generator or other modulation device to generate a switching drive signal to control the switching of the power electronic converter.

[0133] It can be understood that, through the new energy cluster unified synchronization control method of the present invention, the station is equivalent to an aggregate with a single phase control in terms of dynamic characteristics, which physically reduces the original multi-input multi-output coupled system composed of multiple independent PLLs to a decoupled system driven by a single phase reference, thereby eliminating the mutual oscillation mode between each converter.

[0134] In another embodiment of the present invention, in the scenario of a new energy aggregation station, the station-level synchronization control module is deployed at the aggregation station level to provide a unified phase reference signal for multiple geographically dispersed new energy stations.

[0135] The power electronic converters in each of the aforementioned new energy power stations receive the unified phase reference signal through a communication network and use it as the basis for coordinate transformation orientation, thereby achieving synchronous and coordinated control over a wider range.

[0136] Embodiment 2 of the present invention provides a unified synchronization control system for new energy clusters, based on the unified synchronization control method for new energy clusters described in Embodiment 1, comprising: A synchronization control module is used to generate a unified phase reference signal, which is used to provide a phase reference source for all power electronic converters in the new energy cluster. A communication network is used to connect the synchronization control module and the power electronic converter, and to transmit a unified phase reference signal; The controller for multiple power electronic converters includes a signal receiving module, a communication fault detection module, a orientation data generation module, a unified coordinate generation module, a coordinate transformation module, a power control loop, and a current control loop, wherein: The signal receiving module is used to receive a unified phase reference signal through the communication network; The communication fault detection module is used to determine whether the power electronic converter is in normal mode or communication fault mode. The orientation reference generation module is used to directly use the unified phase reference signal as the orientation reference for coordinate transformation when the communication fault detection module outputs the normal mode, and to use the phase output by the local phase-locked loop as the orientation reference for coordinate transformation when the communication fault detection module outputs the communication fault mode. The unified coordinate generation module is used to generate a unified rotating coordinate system based on the coordinate transformation orientation criteria; The coordinate transformation module is used to perform coordinate transformation and inverse coordinate transformation on the input and output of the power control and current control loops based on a unified rotating coordinate system. The power control and current control circuits are used to perform unified synchronous control of grid-connected power.

[0137] Preferably, the synchronization control module includes any of the following units: The voltage measurement and phase-locked loop unit is used to collect the voltage of the high-voltage main grid into which the new energy cluster is connected and extract phase information; Synchronous machine interface unit, used to acquire and process the rotor position signal of the synchronous machine; The virtual synchronizer generation unit is used to generate phase signals based on the virtual rotor motion equations.

[0138] Preferably, the power control circuit of each power electronic converter autonomously determines the active power command based on the input status of the primary energy source or the upper-level dispatch command, and determines the reactive power command based on the voltage control command issued by the synchronization control module.

[0139] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0140] Computer-readable storage media can be tangible devices capable of holding and storing instructions for use by an instruction execution device. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0141] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.

[0142] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing the status information of the computer-readable program instructions to implement various aspects of this disclosure.

[0143] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A unified synchronous control method for a new energy cluster, wherein each new energy power generation unit and / or energy storage unit in the new energy cluster is grid-connected and controlled via a power electronic converter, characterized in that, The control method includes the following steps: Step 1: Generate a unified phase reference signal; Step 2: Distribute the unified phase reference signal to each power electronic converter in the new energy cluster, and simultaneously determine the operating mode of the power electronic converter. When it is in normal mode, execute step 3. When it is in communication failure mode, use the phase output of the local phase-locked loop as the coordinate transformation orientation basis. When the mode changes, the set switching control strategy is used for transition. The switching control strategy includes: When the power electronic converter switches from normal mode to communication fault mode, the phase difference at the current moment is calculated, and a slow-release compensation strategy is adopted during the set switching transition time. The transition phase is used as the basis for coordinate transformation orientation. When the power electronic converter switches back from communication fault mode to normal mode, it calculates the real-time phase difference, generates angular frequency compensation, injects the angular frequency compensation into the integral stage of the local phase-locked loop, obtains the compensated phase, and performs synchronization between the local phase and the remote phase until the absolute value of the real-time phase difference is less than the set phase difference threshold and continues for a set time, at which point synchronization is considered complete. Step 3: Replace the phase output of the local phase-locked loop with the received unified phase reference signal as the basis for coordinate transformation orientation to generate a unified rotating coordinate system; Step 4: The power control and current control links of each power electronic converter generate modulation wave signals based on a unified rotating coordinate system. The modulation wave signals are input to the modulation device to obtain switching drive signals. The power electronic converters perform grid-connected power unified synchronous control according to the switching drive signals.

2. The unified synchronization control method for new energy clusters according to claim 1, characterized in that: In step 1, the methods for generating a unified phase reference signal include: The generation can be based on the voltage phase-locked loop of the high-voltage main grid into which the new energy cluster is connected, the generation can be based on the rotor position signal of the synchronous machine, or the self-synchronization generation can be based on the virtual synchronous machine algorithm.

3. The unified synchronization control method for new energy clusters according to claim 2, characterized in that: The generation of a unified phase reference signal based on the voltage phase-locked loop of the high-voltage main grid into which the new energy cluster is connected includes the following steps: The voltage signal is collected from the high-voltage bus voltage or the three-phase voltage signal at the grid connection point of the new energy cluster, and the voltage signal is generated through coordinate transformation. q Axial components; A phase-locked loop (PLL) structure is adopted, and the voltage of the high-voltage side bus or the grid connection point is set. q The reference value for the axis component is 0, and the phase output by the phase-locked loop at this time is used as the unified phase reference signal. θ ref It can be expressed by the following formula: In the formula, ω ref To unify the angular frequency reference signal, ω g0 The rated angular frequency, and These are the proportional and integral gains of the phase-locked loop, respectively. v gq The voltage of the high-voltage side bus or the voltage at the grid connection point. q Axial components.

4. The unified synchronization control method for new energy clusters according to claim 2, characterized in that: Generating a unified phase reference signal based on the synchronous machine rotor position signal includes the following steps: The mechanical position signal of the synchronous machine rotor connected to the same high-voltage busbar as the new energy cluster is collected. Based on the number of pole pairs of the synchronous machine, the mechanical angle is converted into an electrical angle as a unified phase reference signal. θ ref It can be expressed by the following formula: In the formula, p Let be the number of pole pairs of the synchronous machine. θ m This is the mechanical position signal of the rotor. θ 0 represents the initial phase compensation angle.

5. The unified synchronization control method for new energy clusters according to claim 4, characterized in that: For synchronous machines that lack or cannot be equipped with rotor position measuring devices, a unified phase reference signal is generated by using the phase-locked angle of the three-phase transient internal potential to replace the rotor position signal. This includes the following steps: Calculate static α - β The transient internal potential in the coordinate system is expressed by the following formula: In the formula, , These are the transient internal potentials. α Axial components, β Axial components, , These are the output voltages of the synchronous machine. α Axial components, β Axial components, , These are the output currents of the synchronous machine. α Axial components, β Axial components, The equivalent resistance of the stator of the synchronous machine. The transient reactance of the synchronous machine; For static α - β The transient internal potential in the coordinate system is transformed inversely to obtain the three-phase transient internal potential. Phase-locking is then performed on the three-phase transient internal potential to obtain a unified phase reference signal. θ ref .

6. The unified synchronization control method for new energy clusters according to claim 2, characterized in that: The self-synchronization generation of a unified phase reference signal based on the virtual synchronizer algorithm includes the following steps: A virtual rotor motion equation is constructed, and a unified phase reference signal is generated using the virtual angular frequency integral in the virtual rotor motion equation. θ ref .

7. The unified synchronization control method for new energy clusters according to claim 1, characterized in that: In step 2, the methods for determining the operating mode of the power electronic converter include: heartbeat packet timeout detection, phase and frequency validity verification, and communication quality monitoring. When a communication fault is detected by any of these methods, the power electronic converter is considered to be in a communication fault mode. When no communication fault is detected by any of these methods, the power electronic converter is considered to be in a normal mode.

8. The unified synchronization control method for new energy clusters according to claim 7, characterized in that: The heartbeat timeout detection includes: every set period of time. T hb Send heartbeat packets to each power electronic converter; if the power electronic converter is in 3... T hb If no heartbeat packet is received within a certain time, the communication is considered interrupted.

9. The unified synchronization control method for new energy clusters according to claim 7, characterized in that: The phase frequency validity verification includes: constructing a phase continuity verification mechanism and an angular frequency range verification mechanism; if either validity verification is not met, a communication failure is determined. The phase continuity verification mechanism is expressed by the following formula: In the formula, , They are respectively the first k sequence k -1 unified phase reference signal sent out, The set transition threshold; The angular frequency range verification mechanism is expressed by the following formula: In the formula, ω ref To unify the angular frequency reference signal, ω g0 The rated angular frequency, This is the angular frequency threshold.

10. The unified synchronization control method for new energy clusters according to claim 7, characterized in that: The communication quality monitoring includes: real-time monitoring of communication latency and packet loss rate; when the communication latency exceeds a set communication latency threshold or the packet loss rate exceeds a set packet loss rate threshold, a communication fault is determined and a pre-alarm is triggered.

11. The unified synchronization control method for new energy clusters according to claim 1, characterized in that: When the power electronic converter switches from normal mode to communication fault mode, the transition phase is calculated using the following formula: In the formula, θ trans ( t () represents the transition phase. for t The phase of the local phase-locked loop output at any given time, Δ θ 0 represents the initial phase difference. t 0 represents the switching trigger time. T trans To switch the transition duration, To switch the phase of the local phase-locked loop output at the trigger time, This refers to the unified phase reference signal received by the power electronic converter at the switching trigger moment.

12. The unified synchronization control method for new energy clusters according to claim 1, characterized in that: When the power electronic converter switches back from communication failure mode to normal mode, the compensated phase is calculated using the following formula: In the formula, The compensated phase, The angular frequency of the local phase-locked loop integrator is [value]. This is the angular frequency compensation amount. and These are the proportional and integral gains of the PI controller, respectively. For real-time phase difference, for t The phase of the local phase-locked loop output at any given time. for t The unified phase reference signal received by the power electronic converter at any given time.

13. The unified synchronization control method for new energy clusters according to claim 1, characterized in that: Step 3, generating a unified rotating coordinate system based on the coordinate transformation orientation criteria, includes: All power electronic converters in normal mode use a unified phase reference signal. θ ref As the rotation angle of the Park transform, the unified orientation d - q Coordinate system.

14. The unified synchronization control method for new energy clusters according to claim 1, characterized in that: Step 4 includes: Step 4.1: Construct the power control loop for each power electronic converter based on a unified rotating coordinate system. The active power is autonomously adjusted according to the input status of the primary energy source or the upper-level dispatch command, while the reactive power is coordinated and controlled according to the voltage command of the new energy cluster. Step 4.2: Based on the power control loop, construct a power loop control model in a unified rotating coordinate system, and calculate the current loop reference value through the power outer loop and instantaneous power theory. Step 4.3: Construct the current control loop for each power electronic converter, perform closed-loop current control based on the current loop reference value, and after inductor voltage decoupling and grid voltage feedforward, generate three-phase switch modulation wave signals based on a unified rotating coordinate system using inverse Park transformation. Step 4.4: Generate a switch drive signal based on the modulation wave signal of the three-phase switch tubes to control the switching of the power electronic converter.

15. The unified synchronization control method for new energy clusters according to claim 14, characterized in that: While performing active power control, each power electronic converter activates the positive damping generation module to generate an additional damping power command by utilizing the change in angular velocity difference between the local backup phase-locked loop and the remote unified phase reference, which is then superimposed on the original active power command.

16. The unified synchronization control method for new energy clusters according to claim 14, characterized in that: The reactive power command is generated based on the voltage control command issued by the synchronization control module, and is expressed by the following formula: In the formula, Q ref This is a reactive power command. This is the original reactive power instruction. This is the reactive power regulation coefficient. This is a reference value for the inverter output voltage amplitude. This is a measured value of the actual output voltage amplitude of the power electronic converter. v od and v oq These are the AC output voltages of the power electronic converter. d shaft and q Axial components.

17. The unified synchronization control method for new energy clusters according to claim 14, characterized in that: The power loop control model in a unified rotating coordinate system is expressed by the following formula: In the formula, P ref and Q ref These are the active power and reactive power command values ​​that the AC side of the power electronic converter exchanges with external systems. v od and v oq These are the AC output voltages of the power electronic converter. d shaft and q Axial components, i Ldref and i Lqref These are the reference values ​​for the AC output current of the power electronic converter. d shaft and q Axial components.

18. The unified synchronization control method for new energy clusters according to claim 14, characterized in that: The frequency domain equations for current closed-loop control are as follows: In the formula, v mdref and v mqref These are the modulation wave signals generated by the current control circuit. d shaft and q Axial components, k pi and k ii These are the P and I parameters of the current loop, respectively. i Ld and i Lq These are the AC side inductor currents of the power electronic converter. d shaft and q Axial components, ω The angular frequency of the AC output current of the power electronic converter. L For the AC side inductance of the power electronic converter, v od and v oq These are the AC output voltages of the power electronic converter. d shaft and q Axial components.

19. A unified synchronization control system for a new energy cluster, based on the unified synchronization control method for a new energy cluster according to any one of claims 1-18, characterized in that, include: Synchronization control module, used to generate a unified phase reference signal; A communication network is used to connect the synchronization control module and the power electronic converter, and to transmit a unified phase reference signal; The controller for multiple power electronic converters includes a signal receiving module, a communication fault detection module, a orientation data generation module, a unified coordinate generation module, a coordinate transformation module, a power control loop, and a current control loop, wherein: The signal receiving module is used to receive a unified phase reference signal through the communication network; The communication fault detection module is used to determine whether the power electronic converter is in normal mode or communication fault mode. The orientation reference generation module is used to directly use the unified phase reference signal as the orientation reference for coordinate transformation when the communication fault detection module outputs the normal mode, and to use the phase output by the local phase-locked loop as the orientation reference for coordinate transformation when the communication fault detection module outputs the communication fault mode. The unified coordinate generation module is used to generate a unified rotating coordinate system based on the coordinate transformation orientation criteria; The coordinate transformation module is used to perform coordinate transformation and inverse coordinate transformation on the input and output of the power control and current control loops based on a unified rotating coordinate system. The power control and current control circuits are used to perform unified synchronous control of grid-connected power.

20. The unified synchronization control system for new energy clusters according to claim 19, characterized in that: The synchronization control module includes any of the following units: The voltage measurement and phase-locked loop unit is used to collect the voltage of the high-voltage main grid into which the new energy cluster is connected and extract phase information; Synchronous machine interface unit, used to acquire and process the rotor position signal of the synchronous machine; The virtual synchronizer generation unit is used to generate phase signals based on the virtual rotor motion equations.

21. The unified synchronization control system for new energy clusters according to claim 19, characterized in that: Each power electronic converter's power control circuit autonomously determines the active power command based on the input status of the primary energy source or the upper-level dispatch instruction, and determines the reactive power command based on the voltage control command issued by the synchronization control module.

22. A computer device, comprising a memory, a processor, and a computer program stored in the memory; characterized in that: The processor executes the computer program to implement the steps of the method according to any one of claims 1-18.

23. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the method according to any one of claims 1-18.

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