Black start method and device for self-synchronizing parallel connection and stable control of new energy station

Abstract

The invention relates to a black-start method and device for self-synchronizing parallel connection and stable control of a new energy station, and the method comprises the steps: controlling each power generation unit of the new energy station to carry out the initialization through the DC side energy storage of the power generation unit in response to a black-start instruction, and generating the voltage and frequency of an independently-established island of the new energy station; performing self-synchronization among the power generation units based on the island voltage and frequency, and performing oscillation suppression on the parallel connection process of the power generation units by using adjustable virtual impedance so as to establish a stable parallel power generation unit system; the impedance of the power generation unit system is monitored online in real time, virtual impedance parameters are adjusted in a self-adaptive mode according to a preset impedance stability criterion, and loads are input step by step; and when the voltage difference and the frequency difference in the gradual load input process are smaller than a preset threshold condition, a parallel circuit breaker in the new energy station is controlled to be closed so as to realize black start.

Description

Technical Field

[0001] This application relates to the field of smart grid technology, and in particular to a black-start method, device, computer equipment, storage medium, and computer program product for self-synchronization, parallel connection, and stability control of new energy power plants. Background Technology

[0002] With the advancement of the "dual carbon" goals, the penetration rate of renewable energy generation in the power system continues to rise. Traditional black-start power sources rely on conventional synchronous units such as hydropower units and gas turbines, which suffer from slow start-up speeds and limited geographical distribution, making it difficult to meet the recovery needs of future high-proportion renewable energy power grids. Against this backdrop, utilizing renewable energy power plants as black-start power sources has become an important direction for building resilient power grids.

[0003] However, black start of renewable energy power plants faces two major challenges. The first is the self-synchronization and parallel connection problem. In the initial stage of black start, the power grid is in a passive "island" mode. Multiple renewable energy power generation units need to autonomously achieve voltage, frequency, and phase synchronization and parallel connection without relying on external synchronization signals, while controlling the inrush current at the moment of parallel connection. The second is the stability problem. During black start, the system strength is extremely weak and the equivalent impedance is high. The interaction between the renewable energy converter and the network impedance can easily induce broadband oscillations, leading to black start failure.

[0004] Traditional black-start technologies often employ a "master-slave control" strategy, where a master unit establishes voltage and frequency, and slave units track the master unit via a phase-locked loop (PLL) and then connect in parallel. However, this strategy has significant drawbacks: a failure of the master unit can cause the entire system to collapse, resulting in poor reliability; furthermore, it places extremely high demands on the dynamic performance of the PLL, making it prone to instability under weak grid conditions and unable to achieve effective black-start for renewable energy power plants. Summary of the Invention

[0005] Based on this, it is necessary to provide a reliable and effective black-start method, device, computer equipment, computer-readable storage medium, and computer program product for self-synchronization, parallel connection, and stable control of new energy power stations to address the aforementioned technical problems.

[0006] Firstly, this application provides a black-start method for self-synchronization, parallel connection, and stable control of new energy power stations. The method includes: In response to the black start command, the system controls each power generation unit of the new energy power station to initialize using its own DC-side energy storage, generating the island voltage and frequency that the new energy power station establishes autonomously. Self-synchronization between power generation units is performed based on the island voltage and frequency, and oscillation suppression is achieved during the parallel connection process of power generation units using adjustable virtual impedance, so as to build a stable parallel power generation unit system. The impedance of the power generation unit system is monitored in real time, and the virtual impedance parameters are adaptively adjusted according to the preset impedance stability criterion, and the load is gradually connected. When the voltage difference and frequency difference are less than the preset threshold conditions during the gradual load input process, the parallel circuit breaker in the new energy power station is closed to achieve black start.

[0007] In one embodiment, the self-synchronization between the power generation units based on the island voltage and frequency, and the oscillation suppression of the parallel connection process of the power generation units using adjustable virtual impedance to form a stable parallel power generation unit system, include: Based on the island voltage and frequency, virtual orthogonal electromotive force is used to achieve self-synchronization between each power generation unit; An adjustable virtual impedance is used to suppress oscillations during the parallel connection of each power generation unit, so as to build a stable parallel power generation unit system.

[0008] In one embodiment, the self-synchronization between power generation units based on the island voltage and frequency using virtual orthogonal electromotive force includes: Based on the island voltage and frequency, the initial state data of each power generation unit is determined; Obtain a preset virtual orthogonal electromotive force gain coefficient, and determine the orthogonal voltage component based on the virtual orthogonal electromotive force gain coefficient; Self-synchronization between each power generation unit is performed based on the initial state data superimposed with the orthogonal voltage components.

[0009] In one embodiment, the self-synchronization between the power generation units based on the initial state data superimposed with the orthogonal voltage components includes: The orthogonal voltage component is superimposed on the output voltage in the initial state data, generating an additional active power disturbance; The additional active power disturbance is fed back to the frequency through the droop control equation; By utilizing the correlation between the additional active power disturbance and the phase difference between each power source, an equivalent virtual synchronous power is constructed. Synchronous torque is generated based on the virtual synchronous power, thereby achieving self-synchronization between each power generation unit.

[0010] In one embodiment, the self-synchronization between the power generation units based on the island voltage and frequency, and the oscillation suppression of the parallel connection process of the power generation units using adjustable virtual impedance to form a stable parallel power generation unit system, include: The frequency and phase information of each power generation unit are determined based on the island voltage and frequency. The frequency and phase information of different power generation units are exchanged through a communication network between the various power generation units; A distributed consensus algorithm is used to coordinate and adjust the frequency and phase of each power generation unit in order to achieve self-synchronization among the power generation units. An adjustable virtual impedance is used to suppress oscillations during the parallel connection of each power generation unit, so as to build a stable parallel power generation unit system.

[0011] In one embodiment, the real-time online monitoring of the impedance of the power generation unit system, adaptively adjusting the virtual impedance parameters according to a preset impedance stability criterion, and gradually adding load includes: Inject a preset frequency band test signal or add natural disturbances to the grid connection point of the power generation unit system; Online real-time measurement of the equivalent impedance corresponding to the grid connection point; Based on the Nyquist stability criterion of impedance ratio, the stability of the output impedance of the converter in the new energy power station and the ratio of the equivalent impedance is analyzed. If there is a risk of instability, the virtual impedance of each of the power generation units is adjusted to dynamically reshape the output impedance of the converter in the new energy power station. If there is no risk of instability, the load will be gradually increased.

[0012] Secondly, this application also provides a black start device for self-synchronization, parallel connection, and stable control of new energy power stations. The device includes: The initialization module is used to respond to the black start command, control each power generation unit of the new energy power station to initialize using its own DC side energy storage, and generate the island voltage and frequency that the new energy power station establishes autonomously; The synchronization and oscillation suppression module is used to perform self-synchronization between each power generation unit based on the island voltage and frequency, and to suppress oscillation during the parallel connection process of each power generation unit using adjustable virtual impedance, so as to build a stable parallel power generation unit system. The impedance stabilization module is used to monitor the impedance of the power generation unit system in real time, adaptively adjust the virtual impedance parameters according to the preset impedance stabilization criterion, and gradually connect the load. The startup module is used to control the closure of parallel circuit breakers in the new energy power station to achieve black start when the voltage difference and frequency difference are less than preset threshold conditions during the gradual load input process.

[0013] Thirdly, this application also provides a computer device. The computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to perform the following steps: In response to the black start command, the system controls each power generation unit of the new energy power station to initialize using its own DC-side energy storage, generating the island voltage and frequency that the new energy power station establishes autonomously. Self-synchronization between power generation units is performed based on the island voltage and frequency, and oscillation suppression is achieved during the parallel connection process of power generation units using adjustable virtual impedance, so as to build a stable parallel power generation unit system. The impedance of the power generation unit system is monitored in real time, and the virtual impedance parameters are adaptively adjusted according to the preset impedance stability criterion, and the load is gradually connected. When the voltage difference and frequency difference are less than the preset threshold conditions during the gradual load input process, the parallel circuit breaker in the new energy power station is closed to achieve black start.

[0014] Fourthly, this application also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program thereon, which, when executed by a processor, performs the following steps: In response to the black start command, the system controls each power generation unit of the new energy power station to initialize using its own DC-side energy storage, generating the island voltage and frequency that the new energy power station establishes autonomously. Self-synchronization between power generation units is performed based on the island voltage and frequency, and oscillation suppression is achieved during the parallel connection process of power generation units using adjustable virtual impedance, so as to build a stable parallel power generation unit system. The impedance of the power generation unit system is monitored in real time, and the virtual impedance parameters are adaptively adjusted according to the preset impedance stability criterion, and the load is gradually connected. When the voltage difference and frequency difference are less than the preset threshold conditions during the gradual load input process, the parallel circuit breaker in the new energy power station is closed to achieve black start.

[0015] Fifthly, this application also provides a computer program product. The computer program product includes a computer program that, when executed by a processor, performs the following steps: In response to the black start command, the system controls each power generation unit of the new energy power station to initialize using its own DC-side energy storage, generating the island voltage and frequency that the new energy power station establishes autonomously. Self-synchronization between power generation units is performed based on the island voltage and frequency, and oscillation suppression is achieved during the parallel connection process of power generation units using adjustable virtual impedance, so as to build a stable parallel power generation unit system. The impedance of the power generation unit system is monitored in real time, and the virtual impedance parameters are adaptively adjusted according to the preset impedance stability criterion, and the load is gradually connected. When the voltage difference and frequency difference are less than the preset threshold conditions during the gradual load input process, the parallel circuit breaker in the new energy power station is closed to achieve black start.

[0016] The aforementioned black-start method, device, computer equipment, storage medium, and computer program product for self-synchronization, parallel connection, and stable control of new energy power stations respond to black-start commands, control each power generation unit of the new energy power station to initialize using its own DC-side energy storage, and generate an island voltage and frequency autonomously established by the new energy power station; perform self-synchronization between power generation units based on the island voltage and frequency, and use adjustable virtual impedance to suppress oscillations during the parallel connection process of each power generation unit to form a stable parallel power generation unit system; monitor the impedance of the power generation unit system in real time, adaptively adjust the virtual impedance parameters according to the preset impedance stability criterion, and gradually connect the load; when the voltage difference and frequency difference are less than the preset threshold conditions during the gradual load connection process, control the parallel circuit breaker in the new energy power station to close, thereby achieving black start. Throughout the process, the system achieves autonomous startup by initializing island voltage and frequency using the DC-side energy storage of the power generation unit itself; it quickly establishes a stable parallel power generation unit system by employing self-synchronization and adjustable virtual impedance oscillation suppression; it monitors impedance in real time and adaptively adjusts virtual impedance parameters to ensure system stability and gradually loads the system; and finally, it closes the parallel circuit breaker when the voltage difference and frequency difference threshold conditions are met, reliably and effectively achieving black start of the new energy power station. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating a black start method for self-synchronization, parallel connection, and stability control of a new energy power station in one embodiment. Figure 2 This is a flowchart illustrating the black start method for self-synchronization, parallel connection, and stability control of new energy power stations in another embodiment. Figure 3 This is a schematic diagram of a sub-process of S600 in one embodiment; Figure 4 This is a structural block diagram of a black start device for self-synchronization parallel connection and stability control of a new energy power station in one embodiment; Figure 5 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0019] In one embodiment, such as Figure 1 As shown, a black start method for self-synchronization, parallel connection, and stability control of new energy power plants is provided, including the following steps: S200: Responding to the black start command, it controls each power generation unit of the new energy power station to initialize using its own DC-side energy storage, generating the island voltage and frequency that the new energy power station establishes autonomously.

[0020] When a power system fault occurs or a black start is required, a black start command is issued to the renewable energy power station. Each power generation unit within the station, such as photovoltaic power generation units (using photovoltaic-supported energy storage) and wind power generation units (using wind turbine blade energy storage), starts using its DC-side energy storage equipment. Each power generation unit can employ a grid-based strategy based on pre-synchronous power frequency droop control as the underlying control layer. Under this grid-based strategy, the power generation unit can autonomously establish its islanded voltage and frequency based on its own energy storage capacity, simulating the characteristics of a traditional synchronous generator through a pre-synchronous power frequency droop control algorithm. This step provides a base voltage and frequency reference for subsequent self-synchronizing parallel operation, enabling each power generation unit to independently generate stable power without external grid support, thus creating the initial conditions for the system's black start.

[0021] Specifically, each power generation unit adopts a grid-based control strategy based on pre-synchronous power frequency droop control as the underlying control. The control equations are as follows: Frequency control: ωi = ω' - mp × (Pi - P'); Voltage control: Vi = V' - nq × (Qi - Q'); In the above formula, Vi and ωi are the output voltage amplitude and angular frequency of the i-th power generation unit, respectively; ω' and V' are the rated frequency and voltage setting value, respectively; Qi and Pi are the actual reactive power and active power output of the i-th power generation unit, respectively; Q' and P' are the preset reactive power reference value and active power reference value, respectively, which are usually set to 0 during the black start phase; nq and mp are the reactive power-voltage droop coefficient and active power-frequency droop coefficient, respectively.

[0022] S400: Self-synchronization between power generation units is achieved based on island voltage and frequency, and oscillation suppression is performed during the parallel connection process of power generation units using adjustable virtual impedance, so as to form a stable parallel power generation unit system.

[0023] After each generating unit establishes its islanded voltage and frequency, self-synchronization is performed between them based on these autonomously established voltages and frequencies. During self-synchronization, each generating unit automatically adjusts its output by detecting the voltage phase difference and frequency difference between itself, gradually bringing their voltages and frequencies closer to uniformity. Simultaneously, to suppress potential oscillations during parallel operation, an adjustable virtual impedance is introduced. This adjustable virtual impedance can be dynamically adjusted according to the actual conditions during parallel operation. By appropriately setting the adjustable virtual impedance, the power distribution characteristics between generating units can be altered, reducing power oscillations caused by parallel operation, thus successfully establishing a stable parallel generating unit system. The key to this step is achieving seamless parallel operation of the generating units, ensuring stable system operation and providing reliable power support for subsequent load inputs.

[0024] S600: Monitors the impedance of the power generation unit system in real time, adaptively adjusts the virtual impedance parameters according to the preset impedance stability criterion, and gradually connects to the load.

[0025] After the power generation unit system is stably connected in parallel, it is necessary to monitor the impedance of the entire system in real time. This can be achieved through monitoring equipment installed in the system to continuously acquire impedance information. The monitored impedance data is analyzed and judged based on pre-set impedance stability criteria. If system impedance instability is detected, such as impedance values ​​exceeding the normal range or excessive impedance changes, the system will adaptively adjust virtual impedance parameters. By adjusting the virtual impedance parameters, the system's impedance characteristics can be altered, restoring it to a stable state. Based on stable system impedance, the load is gradually supplied according to a predetermined plan. Each power generation unit automatically allocates power through its droop characteristics, rationally undertaking the power of the supplied load based on its own capacity and system demand. Simultaneously, adaptive impedance reshaping technology further maintains stable system operation. The purpose of this step is to gradually restore load power supply while ensuring system stability, thus ensuring the system's safety and reliability.

[0026] S800: When the voltage difference and frequency difference are less than the preset threshold conditions during the gradual load input process, the parallel circuit breaker in the new energy power station is closed to achieve black start.

[0027] During the gradual load increase, the voltage and frequency differences between each power generation unit are continuously monitored. When both voltage and frequency differences are less than preset threshold conditions, it indicates that the operating states of each power generation unit are very similar, and the system has reached a state where it can operate stably in parallel. At this point, the control system issues a command to close the parallel circuit breaker. The closing of the parallel circuit breaker connects the power generation units more tightly together, forming a complete new energy power station system, thus achieving black start. This step is a crucial part of the black start process. By precisely controlling the closing timing of the parallel circuit breaker, it ensures a smooth transition during load increase, ultimately completing the black start of the new energy power station and restoring power supply to external loads.

[0028] The aforementioned black-start method for self-synchronization, parallel connection, and stable control of renewable energy power plants responds to black-start commands by controlling each power generation unit of the power plant to initialize using its own DC-side energy storage, generating an islanded voltage and frequency autonomously established by the power plant. Based on the islanded voltage and frequency, self-synchronization between power generation units is performed, and adjustable virtual impedance is used to suppress oscillations during the parallel connection process of each power generation unit, thus establishing a stable parallel power generation unit system. The impedance of the power generation unit system is monitored online in real time, and the virtual impedance parameters are adaptively adjusted according to a preset impedance stability criterion, gradually introducing load. When the voltage difference and frequency difference are less than preset threshold conditions during the gradual load introduction process, the parallel circuit breaker in the renewable energy power plant is closed to achieve black start. Throughout the process, autonomous start is achieved by initializing and generating islanded voltage and frequency using the power generation units' own DC-side energy storage; oscillation suppression using self-synchronization and adjustable virtual impedance quickly establishes a stable parallel power generation unit system; impedance is monitored in real time and virtual impedance parameters are adaptively adjusted to ensure system stability, gradually introducing load; finally, the parallel circuit breaker is closed when the voltage difference and frequency difference threshold conditions are met, reliably and effectively achieving black start of the renewable energy power plant.

[0029] In one embodiment, such as Figure 2 As shown, a stable parallel power generation unit system is constructed by self-synchronizing each power generation unit based on islanded voltage and frequency, and by using adjustable virtual impedance to suppress oscillations during the parallel connection process of each power generation unit. S420: Self-synchronization between power generation units is achieved by using virtual orthogonal electromotive force based on island voltage and frequency.

[0030] After each power generation unit in the renewable energy power station completes initialization and generates islanded voltage and frequency, a key technical means, virtual orthogonal electromotive force (EMF), is introduced to enable stable and accurate self-synchronization. The role of this virtual orthogonal EMF is to change the phase characteristics of the power generation unit's output voltage by introducing a specific orthogonal voltage component into the control loop. During self-synchronization, each power generation unit automatically adjusts its output voltage phase based on its detected voltage and frequency information, as well as the output voltage reference value superimposed with the virtual orthogonal EMF. Since each power generation unit uses the same virtual orthogonal EMF generation method and parameter settings, they gradually bring their voltage phases together during the adjustment process, thus achieving self-synchronization between the power generation units. Compared to traditional synchronization methods, this self-synchronization method has higher flexibility and adaptability, enabling the power generation units to quickly and accurately achieve synchronized operation without external synchronization signals, laying the foundation for subsequent parallel operations.

[0031] S440: Utilizes adjustable virtual impedance to suppress oscillations during the parallel connection of each power generation unit, thereby constructing a stable parallel power generation unit system.

[0032] After each generator unit completes self-synchronization, it enters the parallel connection process. However, during the parallel connection process, due to differences in electrical characteristics and line impedance between generator units, power oscillation problems are easily triggered, seriously affecting the stability and reliability of the parallel system. To solve this problem, frequency domain impedance reshaping technology is used, introducing an adjustable virtual impedance Zv(s) = Rv + sLv into the voltage control loop of each generator unit, where Rv is the virtual resistance and Lv is the virtual inductance.

[0033] The initial parameters for the virtual resistance Rv and virtual inductance Lv are obtained, which can actively shape the converter's output impedance Zout(s) in the frequency domain. Specifically, the output impedance Zout(s) is shaped to exhibit inductive and positive resistive characteristics in the critical frequency band. This characteristic satisfies the passive stability condition and, from a frequency domain perspective, can effectively suppress oscillations that may occur during parallel operation.

[0034] In practice, when the power generation units begin to connect in parallel, the adjustable virtual impedance dynamically adjusts the values ​​of the virtual resistance Rv and virtual inductance Lv based on the real-time operating status of the system. For example, when an oscillation trend is detected in the system, the value of the virtual resistance Rv is appropriately increased to increase the system's damping and dissipate oscillation energy; simultaneously, the value of the virtual inductance Lv is adjusted to change the system's inductive reactance characteristics, making the system's impedance characteristics more stable in the critical frequency band. In this way, the adjustable virtual impedance can suppress oscillations during the parallel connection process in real time, ensuring that the power generation units can be stably connected in parallel, ultimately forming a reliable and stable power generation unit system, providing strong support for subsequent load input and normal system operation.

[0035] In one embodiment, self-synchronization between power generation units based on virtual orthogonal electromotive force using islanded voltage and frequency includes: Step 1: Determine the initial state data of each power generation unit based on the island voltage and frequency.

[0036] After the renewable energy power station responds to the black start command, each power generation unit completes its initialization using its own DC-side energy storage, generating islanded voltage and frequency. At this point, it is necessary to accurately acquire the initial state data of each power generation unit. This initial state data covers key parameters such as voltage amplitude, frequency value, and phase information. For example, voltage and frequency sensors are used to collect the voltage and frequency values ​​at the output terminals of each power generation unit in real time, while a phase detection device is used to determine the initial phase of the voltage.

[0037] Step 2: Obtain the preset virtual orthogonal electromotive force gain coefficient, and determine the orthogonal voltage component based on the virtual orthogonal electromotive force gain coefficient.

[0038] The preset virtual quadrature electromotive force gain coefficient is a pre-calibrated parameter, typically set based on the actual conditions of the renewable energy power station, the characteristics of the power generation units, and the requirements for self-synchronization. This gain coefficient k is an extremely small value, its magnitude directly affecting the amplitude of the quadrature voltage component. After obtaining the preset gain coefficient k, the quadrature voltage component is determined according to the formula ΔVi=k×sin(θi), where θi is the phase variable related to the power generation unit. This quadrature voltage component has the characteristics of extremely small amplitude and the same frequency as the fundamental frequency. The purpose of determining the quadrature voltage component is that it generates an additional active power disturbance ΔPi in the control loop of the power generation unit. This disturbance is fed back to the frequency through the droop control equation, forming ωi=ω'-mP×(Pi+ΔPi-P'). This additional active power disturbance is one of the core driving forces of the self-synchronization process, providing the necessary signal for subsequent synchronization adjustments between power generation units.

[0039] Step 3: Perform self-synchronization between each power generation unit by superimposing orthogonal voltage components on the initial state data.

[0040] After determining the initial state data and orthogonal voltage components of each power generation unit, the orthogonal voltage components are superimposed on the output voltage reference value of the control loop of each power generation unit, and further self-synchronization between the power generation units is achieved.

[0041] Unlike traditional methods that rely on phase-locked loop (PLL) tracking for synchronization, this embodiment uses a self-synchronization method based on virtual orthogonal electromotive force (EMF) that eliminates the need for PLL tracking. This reduces system complexity and dependence on external devices, improves the reliability and stability of the self-synchronization process, and enables more efficient synchronous operation between power generation units, laying the foundation for stable power supply after black start of new energy power plants.

[0042] In one embodiment, self-synchronization between power generation units based on initial state data superimposed with orthogonal voltage components includes: Step 1: Superimpose an orthogonal voltage component onto the output voltage in the initial state data to generate an additional active power disturbance.

[0043] After obtaining the initial state data of each power generation unit, the pre-determined orthogonal voltage components are superimposed on the output voltage. The expression for this orthogonal voltage component is ΔVi=k×sin(θi), where k is a very small gain coefficient, θi is a phase variable related to the power generation unit, and the amplitude of this orthogonal voltage component is very small and its frequency is the same as the fundamental frequency.

[0044] When orthogonal voltage components are superimposed on the output voltage, they alter the phase and amplitude characteristics of the generator unit's output voltage, thereby generating an additional active power disturbance ΔPi in the system. This disturbance is a crucial driving force for the subsequent self-synchronization process, disrupting the original power balance of each generator unit and providing a signal for synchronization adjustments between units. For example, in a wind farm containing multiple generator units, the superposition of orthogonal voltage components will cause changes in the output power of each unit due to voltage variations, resulting in an additional active power disturbance.

[0045] Step 2: Apply the additional active power disturbance feedback to the frequency through the droop control equation.

[0046] The droop control equation is expressed as ωi=ω'-mP×(Pi+ΔPi-P'). Where ωi is the actual frequency of the i-th generating unit, ω is the rated frequency, mp is the droop coefficient, Pi is the actual active power of the i-th generating unit, and ΔPi is the additional active power disturbance generated in step 1.

[0047] Substituting the additional active power disturbance ΔPi into the droop control equation will generate feedback regulation on the frequency of the generating unit. When ΔPi is positive, it indicates that the active power output of the unit has increased, and according to the droop control equation, its frequency ωi will decrease; conversely, when ΔPi is negative, the frequency ωi will increase. This feedback regulation mechanism allows the frequency of each generating unit to be dynamically adjusted according to changes in active power, laying the foundation for the subsequent synchronization process. For example, if the output power of a generating unit increases due to the superposition of orthogonal voltage components, its frequency will decrease accordingly through the droop control equation, thereby gradually reducing the frequency difference with other units.

[0048] Step 3: Utilize the correlation between the additional active power disturbance and the phase difference between each power source to construct an equivalent virtual synchronous power.

[0049] The magnitude of the additional active power disturbance ΔPi is closely related to the phase difference Δθ between adjacent generating units. This correlation allows us to construct an equivalent virtual synchronous power. Specifically, when there is a phase difference between adjacent generating units, the additional active power disturbance causes power to flow between units, similar to the synchronous power generated by the phase difference in a synchronous generator.

[0050] For example, if two adjacent power generation units A and B have a phase lead of unit A, then an additional active power disturbance will cause power to flow from unit A to unit B. This power flow is equivalent to constructing a virtual synchronous power, which can guide the phases of the two units to gradually converge. Through this equivalent virtual synchronous power, frequency domain phase consistency (synchronization) between power generation units can be achieved without relying on traditional phase-locked loop tracking.

[0051] Step 4: Generate synchronous torque based on virtual synchronous power to achieve self-synchronization between each power generation unit.

[0052] The equivalent virtual synchronous power will automatically generate synchronous torque in each power generation unit system. The role of synchronous torque is to cause the frequency and phase of each power generation unit to adjust in the same direction. When there are frequency and phase differences between adjacent power generation units, synchronous torque will act like a "pull," causing the lower frequency unit to accelerate and the higher frequency unit to decelerate, while adjusting the phase, so that the frequency and phase of each unit gradually converge.

[0053] In one embodiment, self-synchronization between power generation units is performed based on island voltage and frequency, and oscillation suppression is achieved during the parallel connection process of power generation units using adjustable virtual impedance, in order to construct a stable parallel power generation unit system, including: Step 1: Determine the frequency and phase information of each power generation unit based on the island voltage and frequency.

[0054] After a renewable energy power station enters islanded operation, each power generation unit will generate its own islanded voltage and frequency based on its characteristics. At this point, it is necessary to accurately acquire the frequency and phase information of each power generation unit. Specifically, this can be achieved by installing high-precision voltage and frequency sensors at the output of the power generation units to collect voltage and frequency data. Advanced phase detection algorithms can then be used to extract accurate phase information from the acquired voltage signals.

[0055] Step 2: Exchange frequency and phase information of different power generation units through the communication network between the power generation units.

[0056] A reliable communication network is established between the various power generation units. This network can be wired or wireless, such as Ethernet or a wireless LAN. Through this network, each power generation unit transmits its own frequency and phase information, determined in step 1, to other units in real time, while simultaneously receiving similar information from other units. The purpose of the communication network is to enable information sharing and interaction. During self-synchronization, each power generation unit needs to understand the status of other units to coordinate and adjust accordingly. By exchanging information through the communication network, each power generation unit can grasp the global frequency and phase distribution, providing necessary data support for subsequent coordination and adjustment using distributed consensus algorithms. For example, in a large-scale renewable energy microgrid, multiple power generation units are distributed in different locations. The communication network allows for rapid and accurate information transmission, ensuring the smooth progress of the self-synchronization process.

[0057] Step 3: Use a distributed consensus algorithm to coordinate and adjust the frequency and phase of each power generation unit to achieve self-synchronization among the power generation units.

[0058] Distributed consensus algorithms are a coordination and control method based on low-speed communication. After obtaining the frequency and phase information of each power generation unit, each power generation unit acts as a node and uses a distributed consensus algorithm to adjust its own frequency and phase. This algorithm, through information exchange and local computation between nodes, gradually brings the frequencies and phases of all nodes closer to consistency.

[0059] Step 4: Use adjustable virtual impedance to suppress oscillations during the parallel connection of each power generation unit in order to build a stable parallel power generation unit system.

[0060] After the individual power generation units achieve self-synchronization, parallel operation is required to establish a stable power generation unit system. However, during parallel operation, differences in electrical parameters and dynamic characteristics among the power generation units may lead to oscillations, affecting system stability. Adjustable virtual impedance is an effective means of suppressing oscillations. By introducing an adjustable virtual impedance into the control loop of the power generation unit, the output impedance characteristics of the power generation unit can be changed, thereby adjusting the power distribution and current distribution in the parallel system. Specifically, based on the real-time state of the system during parallel operation, the magnitude and parameters of the virtual impedance are dynamically adjusted to make the power distribution among the power generation units more reasonable and suppress the generation of oscillations.

[0061] In one embodiment, such as Figure 3 As shown, the impedance of the power generation unit system is monitored in real time, and the virtual impedance parameters are adaptively adjusted according to the preset impedance stability criterion, and the load is gradually applied, including: S610: Inject a preset frequency band test signal or add natural disturbance to the grid connection point of the power generation unit system.

[0062] In this step, two methods are used to obtain the excitation signal for impedance measurement. The first is to inject a test signal with a preset frequency band into the grid connection point of the power generation system. This test signal has a specific frequency range and amplitude characteristics; it is a carefully designed, small signal with a sufficiently small amplitude to not significantly affect the normal operation of the power generation system. Simultaneously, its frequency band covers any critical frequency range that may exist in the system, allowing for comprehensive acquisition of the system's impedance information. The second method utilizes natural disturbances. During the actual operation of the power generation system, it is inevitably affected by various natural factors (such as changes in wind speed and fluctuations in light intensity). These natural disturbances will generate corresponding responses in the system, which can be used as excitation signals for impedance measurement. The purpose of this step is to provide an effective excitation source for subsequent impedance measurements. By injecting a test signal with a preset frequency band or utilizing natural disturbances, the dynamic response of the system at different frequencies can be excited, thus laying the foundation for accurately measuring the equivalent impedance of the grid connection point.

[0063] S620: Online real-time measurement of the equivalent impedance corresponding to the grid connection point.

[0064] Based on the excitation signal obtained in step S610, the equivalent impedance of the grid connection point is measured in real time using an online impedance observer. The online impedance observer is an advanced measurement device that can acquire voltage and current signals at the grid connection point in real time and process these signals through complex algorithms to calculate the equivalent impedance of the grid connection point at the current moment. This observer features high accuracy and high real-time performance, enabling continuous and accurate monitoring of impedance changes during system operation. The key role of this step is to grasp the impedance characteristics of the system's grid connection point in real time.

[0065] S630: Based on the Nyquist stability criterion of impedance ratio, analyze the stability of the output impedance and the ratio of impedance to equivalent impedance of the converter in the new energy power station.

[0066] After obtaining the equivalent impedance at the grid connection point, a stability analysis is performed on the ratio of the converter's output impedance Zout(s) to the equivalent impedance Zgrid(s) at the grid connection point in the renewable energy power plant, based on the Nyquist stability criterion. The Nyquist stability criterion is a classic stability analysis method that determines the stability of the closed-loop system by analyzing the trajectory of the system's open-loop frequency characteristics on the complex plane. In this step, the ratio of the converter's output impedance to the equivalent impedance at the grid connection point is considered as the open-loop transfer function, and its Nyquist curve is plotted. The stability of the system is then determined based on the relationship between the curve and the negative real axis.

[0067] S640: If there is a risk of instability, adjust the virtual impedance of each power generation unit to dynamically reshape the output impedance of the converter in the new energy power station.

[0068] When the analysis results in step S630 indicate that the system has an instability risk, the controller will adaptively adjust the parameters of the virtual impedance Zv(s) of each generator unit. Virtual impedance is an impedance simulated by a control algorithm that can dynamically change the output characteristics of the converter. For example, increasing the virtual resistance Rv can enhance the damping of the system in a specific frequency band, thereby improving system stability. The controller precisely adjusts the parameters of the virtual impedance according to the frequency band and degree of the instability risk, dynamically reshaping the frequency domain characteristics of the converter's output impedance Zout(s).

[0069] S650: If there is no risk of instability, gradually increase the load.

[0070] If the analysis results in step S630 show that the system has no risk of instability, it indicates that the current impedance characteristics of the system can meet the requirements for stable operation, and the load can be gradually added. Gradual load addition is a cautious process that requires increasing the load gradually according to the system's actual carrying capacity and operating status, following a predetermined strategy and sequence. The purpose of this step is to rationally utilize the output capacity of the new energy power generation units while ensuring system stability. By gradually adding load, system instability caused by a sudden increase in load can be avoided, while simultaneously improving the utilization rate of new energy power generation and achieving efficient system operation.

[0071] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0072] Based on the same inventive concept, this application also provides a black-start device for self-synchronization, parallel connection, and stable control of new energy power stations, used to implement the black-start method for self-synchronization, parallel connection, and stable control of new energy power stations as described above. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations of one or more embodiments of the black-start device for self-synchronization, parallel connection, and stable control of new energy power stations provided below can be found in the limitations of the black-start method for self-synchronization, parallel connection, and stable control of new energy power stations described above, and will not be repeated here.

[0073] In one embodiment, such as Figure 4 As shown, a black start device for self-synchronization, parallel connection, and stable control of new energy power stations is provided, comprising: The initialization module 200 is used to respond to the black start command, control each power generation unit of the new energy power station to perform initialization using its own DC side energy storage, and generate the island voltage and frequency that the new energy power station establishes autonomously. The synchronization and oscillation suppression module 400 is used to perform self-synchronization between each power generation unit based on island voltage and frequency, and to suppress oscillation during the parallel connection process of each power generation unit using adjustable virtual impedance, so as to build a stable parallel power generation unit system. The impedance stabilization module 600 is used to monitor the impedance of the power generation unit system in real time, adaptively adjust the virtual impedance parameters according to the preset impedance stability criteria, and gradually connect the load. The starting module 800 is used to control the closure of the parallel circuit breaker in the new energy power station to achieve black start when the voltage difference and frequency difference are less than the preset threshold conditions during the gradual load input process.

[0074] In one embodiment, the synchronization and oscillation suppression module 400 is also used to perform self-synchronization between each power generation unit based on the island voltage and frequency using virtual orthogonal electromotive force; and to suppress oscillation during the parallel connection process of each power generation unit using adjustable virtual impedance, so as to form a stable parallel power generation unit system.

[0075] In one embodiment, the synchronization and oscillation suppression module 400 is further configured to determine the initial state data of each power generation unit based on the island voltage and frequency; obtain a preset virtual orthogonal electromotive force gain coefficient, and determine the orthogonal voltage component based on the virtual orthogonal electromotive force gain coefficient; and perform self-synchronization between each power generation unit based on the initial state data superimposed with the orthogonal voltage component.

[0076] In one embodiment, the synchronization and oscillation suppression module 400 is further configured to superimpose orthogonal voltage components on the output voltage in the initial state data to generate additional active power disturbance; feed the additional active power disturbance back to the frequency through the droop control equation; construct virtual synchronous power by utilizing the correlation between the additional active power disturbance and the phase difference between each power generation source; and generate synchronous torque based on the virtual synchronous power to achieve self-synchronization between each power generation unit.

[0077] In one embodiment, the synchronization and oscillation suppression module 400 is further used to determine the frequency and phase information of each power generation unit based on the island voltage and frequency; exchange the frequency and phase information of different power generation units through the communication network between the power generation units; use a distributed consensus algorithm to coordinate and adjust the frequency and phase of each power generation unit to achieve self-synchronization between the power generation units; and use an adjustable virtual impedance to suppress oscillations during the parallel connection process of each power generation unit to form a stable parallel power generation unit system.

[0078] In one embodiment, the impedance stabilization module 600 is also used to inject a preset frequency band test signal or add natural disturbances to the grid connection point of the power generation unit system; measure the equivalent impedance corresponding to the grid connection point online in real time; analyze the stability of the output impedance of the converter in the new energy power station and the ratio of the equivalent impedance to the impedance ratio Nyquist stability criterion; if there is a risk of instability, adjust the virtual impedance of each power generation unit to dynamically reshape the output impedance of the converter in the new energy power station; if there is no risk of instability, gradually connect the load.

[0079] The various modules in the black start device for self-synchronization, parallel connection, and stable control of the aforementioned new energy power stations can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device in hardware form, or stored in the memory of a computer device in software form, so that the processor can call and execute the corresponding operations of each module.

[0080] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 5As shown, the computer device includes a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When executed by the processor, the computer program implements a black-start method for self-synchronization, parallel connection, and stable control of a new energy power station. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0081] Those skilled in the art will understand that Figure 5 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0082] In one embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the aforementioned black-start method for self-synchronization, parallel connection, and stable control of new energy power stations.

[0083] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored, which, when executed by a processor, implements the aforementioned black-start method for self-synchronization, parallel connection, and stable control of new energy power stations.

[0084] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the aforementioned black-start method for self-synchronization, parallel connection, and stable control of new energy power stations.

[0085] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0086] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0087] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A black start method for new energy station self-synchronization parallel and stable control, characterized in that, The method comprises: in response to a black start instruction, controlling each power generation unit of a new energy station to initialize using self DC side energy storage to generate an island voltage and frequency independently established by the new energy station; based on the island voltage and frequency, self-synchronizing between each power generation unit and using adjustable virtual impedance to suppress oscillation during parallel connection of each power generation unit to form a stable parallel connection power generation unit system; real-time online monitoring of impedance of the power generation unit system, adaptive adjustment of virtual impedance parameters according to a preset impedance stability criterion, and gradual load input; when the voltage difference and frequency difference are less than a preset threshold condition during the gradual load input, controlling a parallel connection circuit breaker in the new energy station to be closed to realize black start.

2. The method of claim 1, wherein, The self-synchronization between each power generation unit based on the island voltage and frequency and the use of adjustable virtual impedance to suppress oscillation during parallel connection of each power generation unit to form a stable parallel connection power generation unit system comprises: based on the island voltage and frequency, using virtual orthogonal electromotive force for self-synchronization between each power generation unit; using adjustable virtual impedance to suppress oscillation during parallel connection of each power generation unit to form a stable parallel connection power generation unit system.

3. The method of claim 2, wherein, The self-synchronization between each power generation unit based on the island voltage and frequency and the use of virtual orthogonal electromotive force comprises: based on the island voltage and frequency, determining initial state data of each power generation unit; acquiring a preset virtual orthogonal electromotive force gain coefficient and determining an orthogonal voltage component based on the virtual orthogonal electromotive force gain coefficient; based on the initial state data, superimposing the orthogonal voltage component for self-synchronization between each power generation unit.

4. The method of claim 3, wherein, The self-synchronization between each power generation unit based on the initial state data and the superimposition of the orthogonal voltage component comprises: superimposing the orthogonal voltage component on the output voltage in the initial state data to generate an additional active power disturbance; through a droop control equation, the additional active power disturbance is fed back to the frequency; using the correlation between the additional active power disturbance and the phase difference between each power generation source, a virtual synchronous power is equivalently constructed; based on the virtual synchronous power, a synchronous torque is generated to realize self-synchronization between each power generation unit.

5. The method of claim 1, wherein, The self-synchronization between each power generation unit based on the island voltage and frequency and the use of adjustable virtual impedance to suppress oscillation during parallel connection of each power generation unit to form a stable parallel connection power generation unit system comprises: based on the island voltage and frequency, determining frequency and phase information of each power generation unit; through a communication network between each power generation unit, the frequency and phase information of different power generation units are exchanged; using a distributed consistency algorithm to coordinate and adjust the frequency and phase of each power generation unit to realize self-synchronization between each power generation unit; using adjustable virtual impedance to suppress oscillation during parallel connection of each power generation unit to form a stable parallel connection power generation unit system.

6. The method of claim 1, wherein, The real-time online monitoring of impedance of the power generation unit system, the adaptive adjustment of virtual impedance parameters according to a preset impedance stability criterion, and the gradual load input comprise: injecting a preset frequency band test signal or adding a natural disturbance to a grid connection point of the power generation unit system; online real-time measurement of the equivalent impedance corresponding to the grid connection point; Based on an impedance ratio Nyquist stability criterion, stability of a ratio of the output impedance of the converter in the new energy station to the equivalent impedance is analyzed. If there is a risk of instability, the virtual impedance of each power generation unit is adjusted, and the output impedance of the converter in the new energy station is dynamically reshaped. If there is no risk of instability, the load is gradually put in.

7. A black start device for self-synchronization and parallel connection and stability control of a new energy station, characterized in that, The device comprises: An initialization module is configured to, in response to a black start instruction, control each power generation unit of the new energy station to perform initialization by using energy storage on a direct current side of the power generation unit, and generate an island voltage and frequency established by the new energy station independently; A synchronization and oscillation suppression module is configured to perform self-synchronization between the power generation units based on the island voltage and frequency, and suppress oscillation in a parallel process of the power generation units by using an adjustable virtual impedance, so as to form a stable parallel power generation unit system; An impedance stability module is configured to monitor impedance of the power generation unit system in real time and online, and adjust a virtual impedance parameter adaptively according to a preset impedance stability criterion, and gradually put in a load; A start module is configured to, when a voltage difference and a frequency difference are less than a preset threshold condition in a process of gradually putting in the load, control a parallel circuit breaker in the new energy station to be closed, so as to realize black start.

8. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that, The processor executes the computer program to realize steps of the method in any one of claims 1 to 6.

9. A computer readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to realize steps of the method in any one of claims 1 to 6.

10. A computer program product comprising a computer program, characterized in that, The computer program is executed by the processor to realize steps of the method in any one of claims 1 to 6.

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