Operation control method and device for follow-up hybrid unit in power plant

Abstract

The invention provides an operation control method and device for a follow-up hybrid unit in a power plant, and the method comprises the steps: employing a node power flow equation, and building a system model; on the basis of the system model, taking whether reactive circulation occurs as a target, and constructing an operation area graph; if the collection terminal voltage regulation value is greater than or equal to the collection terminal voltage change threshold value, judging whether second reactive power of the network-forming unit is located in an area which is above the first reactive power limit and is located at the right of the second reactive power limit; if the collection end voltage regulation value is smaller than the collection end voltage change threshold value, judging whether second reactive power of the network building type unit is located below the first reactive power limit or in an area formed on the left of the second reactive power limit; if yes, outputting a safety instruction; and if not, outputting an unsafe instruction. And the overall operation safety and stability of the hybrid station are obviously improved.

Description

Technical Field

[0001] This application relates to the field of circuit devices or systems for power supply or distribution, and in particular to an operation control method for a hybrid unit in a power plant, an operation control device for a hybrid unit in a power plant, computer equipment, computer-readable storage media, and computer program products. Background Technology

[0002] Grid-connected units are power generation units whose grid-connected operation relies on the external power grid to provide a stable voltage and frequency reference. They track the voltage phase and frequency of the grid in real time through a phase-locked loop (PLL) and adjust their output current accordingly to control the active and reactive power injected into the grid. Grid-integrated units, on the other hand, are power generation units capable of autonomously establishing and maintaining the voltage and frequency of the AC power grid, providing a synchronization reference and stability support for the system. They do not rely on the voltage phase of the external power grid but determine the amplitude and phase of their output voltage through their own control algorithms.

[0003] As new power systems evolve towards a higher proportion of renewable energy, the strength and inertia of the power grid continue to weaken. Traditional grid-connected power plants exhibit inherent limitations, such as high dependence on the grid and insufficient active support capabilities. The introduction of grid-connected technology can empower power plants to autonomously establish voltage frequencies, provide inertia damping, and operate in weak grid conditions, fundamentally enhancing their active support role and operational resilience. However, relying solely on grid-connected units faces practical constraints such as technological maturity, retrofitting costs, and differences in dynamic characteristics. Therefore, the mixed operation of grid-connected and grid-connected units can preserve existing assets and economic efficiency while allowing some units to provide voltage source support and others to flexibly adjust power, achieving a synergistic advantage where the power plant has both a "backbone" and "regulation capability."

[0004] However, when the grid voltage needs to be adjusted due to load changes or dispatch instructions, grid-connected units will proactively change their output voltage to achieve the voltage regulation target, while grid-linked units tend to maintain their original power output. During dynamic adjustment, due to inconsistent voltage references, impedance coupling, and uncoordinated power distribution, a "push-pull" effect of reactive power, i.e., reactive circulating current, will be generated in the parallel circuit. This circulating current will not only lead to equipment overload, increased losses, and protection malfunctions, but also weaken system stability, especially during transient processes such as weak grids or fault ride-throughs, potentially inducing oscillations and instability. Ultimately, this reduces the safety of hybrid power plant operations based on grid-linked and grid-connected units. Summary of the Invention

[0005] The purpose of this application is to provide an operation control method, an operation control device, a computer device, a computer-readable storage medium, and a computer program product for hybrid power plants based on grid-connected and grid-connected units, so as to improve the safety of operation of hybrid power plants based on grid-connected and grid-connected units.

[0006] To address the aforementioned technical problems, this application provides the following technical solutions: The first aspect of this application provides an operation control method for a grid-connected hybrid unit in a power plant. The method includes: establishing a system model based on the collector-end voltage in the power plant, the first terminal voltage, first active power, first reactive power, and first equivalent impedance of the grid-connected unit, the second terminal voltage, second active power, second reactive power, and second equivalent impedance of the hybrid unit, the system equivalent voltage source, and the equivalent impedance of the low-voltage side of the main transformer, using nodal power flow equations. The system model indicates the relationship between the collector-end dp-axis current and voltage, power, and impedance. Based on the system model, an operating region diagram is constructed with the objective of whether reactive current circulation occurs. The horizontal axis of the operating region diagram represents the collector-end voltage and includes a collector-end voltage change threshold. The vertical axis... The second reactive power of the grid-connected generator unit is indicated. The operating area diagram includes the first reactive power limit and the second reactive power limit. The area corresponding to the first and second reactive power limits is used to indicate the absence of reactive power circulation. If the collector voltage regulation value is greater than or equal to the collector voltage change threshold, it is determined whether the second reactive power of the grid-connected generator unit is above the first reactive power limit and within the area to the right of the second reactive power limit. If the collector voltage regulation value is less than the collector voltage change threshold, it is determined whether the second reactive power of the grid-connected generator unit is below the first reactive power limit and within the area to the left of the second reactive power limit. If the determination is yes, a safety command is output; if the determination is no, an unsafe command is output.

[0007] Compared to existing technologies, the operation control method for hybrid units in power plants provided in the first aspect of this application, by establishing a precise system model and constructing an operation area map with the collector voltage and reactive power of the grid-connected units as coordinates, provides clear reactive power circulation risk criteria for hybrid power plants. During Automatic Voltage Control (AVC) adjustments, it can determine in real time whether the current operating point is within a safe zone based on the relationship between the collector voltage target value and the threshold, thereby identifying and warning in advance of reactive power circulation risks that may lead to equipment overload, increased losses, or even system instability. By outputting corresponding safe or unsafe commands, it can guide operators or the automatic control system to take preventative adjustments, effectively avoiding circulation problems caused by control mode conflicts, and significantly improving the overall operational safety and stability of hybrid power plants.

[0008] In other embodiments provided in this application, based on the system model and with the presence or absence of reactive power circulation as the objective, an operating region diagram is constructed, including: deriving boundary operating equations based on the system model and with the presence or absence of reactive power circulation as the objective. , Where, q 2a q represents the first reactive power limit. 2b V represents the second reactive power limit. m_set V represents the threshold voltage change at the collection terminal. m X represents the magnitude of the collector voltage. b p1 represents the equivalent impedance of the low-voltage side of the main transformer, p2 represents the first active power of the grid-connected unit, and p2 represents the second active power of the grid-connected unit. t2 The second equivalent impedance of the grid-type unit is represented; the operating area map is constructed based on the boundary operating equations.

[0009] Starting from the system model, the first reactive power limit determined by specific electrical parameters is rigorously derived. q 2 a Second reactive power limit q 2 b and the threshold voltage change at the collection terminal Vm _ set This gives the constructed operating area map a clear mathematical and physical basis. The limits and thresholds are no longer empirical values ​​or fixed settings, but dynamically change with the actual operating state of the system, thereby ensuring a more accurate and adaptive assessment of reactive power circulation risk and significantly improving the reliability of the safe zone criterion.

[0010] In other embodiments provided in this application, there are multiple grid-connected units and multiple grid-structured units; based on the collection terminal voltage in the power plant, the first terminal voltage, first active power, first reactive power, and first equivalent impedance of the grid-connected units, the second terminal voltage, second active power, second reactive power, and second equivalent impedance of the grid-structured units, the system equivalent voltage source, and the equivalent impedance of the low-voltage side of the main transformer, a system model is established using nodal power flow equations, including: equating multiple grid-connected units and reactive power compensation devices to one grid-connected unit, obtaining the first terminal voltage, first active power, first reactive power, and first equivalent impedance corresponding to one grid-connected unit. The system is defined by the following parameters: active power, first reactive power, and first equivalent impedance; multiple grid-connected generating units are equivalent to one grid-connected generating unit, resulting in the second terminal voltage, second active power, second reactive power, and second equivalent impedance corresponding to the grid-connected generating unit; based on the collection terminal voltage in the power plant, the second terminal voltage, second active power, second reactive power, and second equivalent impedance corresponding to a grid-connected generating unit, the first terminal voltage, first active power, first reactive power, and first equivalent impedance corresponding to a grid-connected generating unit, the system equivalent voltage source, and the equivalent impedance of the low-voltage side of the main transformer, using nodal power flow equations to establish the system model.

[0011] By equivalently aggregating multiple grid-connected units (including reactive power compensation devices) and multiple grid-structured units within a power station into a single unit, the complexity of system modeling and equation solving is significantly reduced, avoiding computational difficulties caused by multivariable coupling. Furthermore, it ensures that the established system model can still accurately reflect the overall electrical characteristics and interactive effects of the original system at the aggregation end. This approach can be directly applied to mixed operation scenarios with arbitrary configurations of unit numbers in actual power stations, significantly improving the versatility and engineering practicality of the method. This enables the circulating current criterion derived from the single-unit model to effectively guide the safe operation of multi-unit systems.

[0012] In other embodiments provided in this application, based on the collection terminal voltage in the power plant, the second terminal voltage, second active power, second reactive power, and second equivalent impedance corresponding to a grid-connected unit, the first terminal voltage, first active power, first reactive power, and first equivalent impedance corresponding to a grid-connected unit, the system equivalent voltage source, and the equivalent impedance of the low-voltage side of the main transformer, a system model is established using nodal power flow equations. This includes: substituting the collection terminal voltage in the power plant, the second terminal voltage, second active power, second reactive power, and second equivalent impedance corresponding to a grid-connected unit, the first terminal voltage, first active power, first reactive power, and first equivalent impedance corresponding to a grid-connected unit, the system equivalent voltage source, and the equivalent impedance of the low-voltage side of the main transformer into the nodal power flow equations; and deriving the nodal power flow equations after substitution to obtain: , Among them, V m Indicates the magnitude of the collector voltage, I md I represents the d-axis current component of the grid-type generator unit. mq I represents the q-axis current component of the grid-type generator unit. 2d I represents the d-axis current component of a grid-connected unit. 2q q represents the q-axis current component of the grid-connected unit, q2 represents the second reactive power of the grid-connected unit, V1 represents the first terminal voltage of the grid-connected unit, and q 1m p1 represents the first reactive power of the grid-connected unit, p2 represents the second active power of the grid-connected unit, and X represents the first reactive power of the grid-connected unit. b q represents the system's equivalent reactance. 2m X represents the second reactive power of a grid-connected unit. t2 X represents the second equivalent impedance of a grid-connected unit. t1 θ represents the first equivalent impedance of the grid-connected unit, and θ represents the phase angle of the collector voltage.

[0013] By accurately substituting the aggregated equivalent unit parameters and system electrical quantities into the nodal power flow equations and performing rigorous mathematical derivation, an explicit set of equations describing the relationship between the dq-axis current components at the collection end and the voltage, power, and impedance of each unit is finally obtained. This fully characterizes the electrical coupling relationship between grid-connected and grid-connected units during mixed operation from a mechanistic perspective, ensuring the physical rationality and mathematical rigor of the circulating current criterion. This makes the final constructed safe operating area have a clear analytical expression and high reliability, thus providing a theoretically solid judgment tool that can be directly applied to engineering calculations for actual system operation.

[0014] In other embodiments provided in this application, before converting multiple grid-connected generator sets and reactive power compensation devices into a single grid-connected generator set and obtaining the first terminal voltage, first active power, first reactive power, and first equivalent impedance corresponding to the grid-connected generator set, the method further includes: normalizing the first terminal voltage, first active power, first reactive power, and first equivalent impedance of each grid-connected generator set, as well as the reactive power output by the reactive power compensation device.

[0015] By standardizing the unit parameters and reactive power compensation device outputs, the actual physical quantities of different capacities and voltage levels are uniformly converted into a relative value system with the system benchmark value as the reference. This eliminates the dimensional influence of specific numerical values, allowing subsequent equivalent aggregation, model establishment, and equation derivation to be performed within a unified, dimensionless mathematical framework, significantly improving the consistency and numerical stability of calculations. Simultaneously, standardization decouples the established analytical model from the specific scale of the system, enhancing the method's versatility and facilitating its application across stations with different capacity configurations. It also lays a standardized foundation for the subsequent parameterized expression and adaptive adjustment of safety boundaries.

[0016] In other embodiments provided in this application, the method further includes: if the determination is negative, adjusting the collection terminal voltage regulation value according to the operating area diagram, so that the range of the first reactive power limit and the second reactive power limit corresponding to the adjusted collection terminal voltage regulation value covers the second reactive power of the grid-type unit.

[0017] When it is determined that the current operating point may lead to reactive power circulation, the boundary of the safe zone can be shifted or adjusted by actively changing the voltage setting. This allows the actual reactive power of the grid-connected units to be brought back into the safe range, upgrading the control strategy from passive risk warning to active risk avoidance. Without changing the inherent control mode of the units, the generation of circulation current can be actively prevented by optimizing the voltage command of the upper level. This not only significantly enhances the autonomous adaptability and collaborative control capability of hybrid power plant operation, but also helps to ensure that the system always operates in the safe zone without circulation current while meeting the voltage regulation requirements of the power grid, thus improving the robustness and practicality of the overall control strategy.

[0018] The second aspect of this application provides an operation control device for a grid-connected hybrid unit in a power plant. The device includes: a first construction module for establishing a system model based on the collector-end voltage in the power plant, the first terminal voltage, first active power, first reactive power, and first equivalent impedance of the grid-connected unit, the second terminal voltage, second active power, second reactive power, and second equivalent impedance of the grid-connected unit, the system equivalent voltage source, and the equivalent impedance of the low-voltage side of the main transformer, using nodal power flow equations. The system model indicates the relationship between the collector-end dp-axis current and voltage, power, and impedance. A second construction module is used to construct an operating area diagram based on the system model, with the presence or absence of reactive power circulation as the objective. The horizontal axis of the operating area diagram represents the collector-end voltage and includes a collector-end voltage change threshold, while the vertical axis represents the grid connection. The second reactive power of the grid-connected generator unit is defined in the operating area diagram, which includes a first reactive power limit and a second reactive power limit. The area corresponding to the first and second reactive power limits is used to indicate the absence of reactive power circulation. A judgment module is used to determine whether the second reactive power of the grid-connected generator unit is above the first reactive power limit and within the area to the right of the second reactive power limit if the collection terminal voltage regulation value is greater than or equal to the collection terminal voltage change threshold; and whether the second reactive power of the grid-connected generator unit is below the first reactive power limit and within the area to the left of the second reactive power limit if the collection terminal voltage regulation value is less than the collection terminal voltage change threshold. A first output module is used to output a safety command if the judgment is yes; and a second output module is used to output an unsafe command if the judgment is no.

[0019] A third aspect of this application 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 method of the second aspect.

[0020] The fourth aspect of this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method of the second aspect.

[0021] The fifth aspect of this application provides a computer program product, including a computer program that, when executed by a processor, implements the method of the second aspect.

[0022] The operation control device for the integrated hybrid unit in the power plant provided in the second aspect of this application, the computer equipment provided in the third aspect, the computer-readable storage medium provided in the fourth aspect, and the computer program product provided in the fifth aspect have the same or similar beneficial effects as the operation control method for the integrated hybrid unit in the power plant provided in the first aspect. Attached Figure Description

[0023] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily understood by reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of this application are illustrated by way of example and not limitation, with the same or corresponding reference numerals denoteing the same or corresponding parts, wherein: Figure 1 This is a flowchart illustrating the operation control method of the hybrid unit in the power plant in this application embodiment. Figure 1 ; Figure 2 This is a schematic diagram of the operating area in an embodiment of this application; Figure 3 This is a flowchart illustrating the operation control method of the hybrid unit in the power plant in this application embodiment. Figure 2 ; Figure 4 This is a schematic diagram of the operation control device for the combined unit in the power plant in the embodiments of this application. Figure 1 ; Figure 5 This is a schematic diagram of the operation control device for the combined unit in the power plant in the embodiments of this application. Figure 2 ; Figure 6 This is a schematic diagram of the structure of the computer device in the embodiments of this application. Detailed Implementation

[0024] Exemplary embodiments of this application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.

[0025] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application shall have the ordinary meaning as understood by one of ordinary skill in the art to which this application pertains.

[0026] In wind farms where grid-connected and grid-connected units operate in combination, when the grid voltage needs to be adjusted, the two types of units will generate reactive circulating currents in the parallel circuit due to differences in control objectives and response characteristics. This can lead to equipment overload, increased losses, protection malfunctions, and threaten the stable operation of the system, ultimately reducing the overall safety of the mixed wind farm.

[0027] The root cause of the above problems is that grid-connected units adopt an autonomous voltage source control mode, while grid-connected units adopt a current source control mode that tracks the grid. During the dynamic adjustment process, the voltage reference is inconsistent and the power distribution is uncoordinated, which leads to reactive power conflicts and circulating currents in the coupling impedance.

[0028] In view of this, embodiments of this application provide an operation control method for hybrid units in a power plant, an operation control device for hybrid units in a power plant, a computer device, a computer-readable storage medium, and a computer program product. By establishing an electrical model of the hybrid power plant, a safe operating area map is derived with the collection terminal voltage and the reactive power of the grid-connected units as coordinates. Based on the comparison between the voltage regulation target and the threshold, the map is used to determine whether the current operating point may cause reactive power circulation, thereby realizing a pre-emptive quantitative assessment and safety warning of the risks of hybrid operation.

[0029] First, the operation control method of the hybrid unit in the power plant provided in the embodiments of this application will be described in detail.

[0030] Figure 1 This is a flowchart illustrating the operation control method of the hybrid unit in the power plant in this application embodiment. Figure 1 See Figure 1 As shown, the method may include: S11: Based on the collection terminal voltage in the power plant, the first terminal voltage, first active power, first reactive power and first equivalent impedance of the grid-type unit, the second terminal voltage, second active power, second reactive power and second equivalent impedance of the grid-type unit, the system equivalent voltage source and the equivalent impedance of the low-voltage side of the main transformer, the nodal power flow equations are used to establish the system model, where the system model is used to indicate the relationship between the dp-axis current of the collection terminal and the voltage, power and impedance.

[0031] The power plant referred to here is a grid-connected renewable energy power station or traditional power plant that includes at least one grid-connected generator unit and at least one grid-building generator unit, with both types of units electrically connected in parallel and connected to the same busbar. For example, in a wind farm using a hybrid operation mode, some wind turbine units are modified or configured to have independent grid-building capabilities (grid-building type), while the remaining units still use the traditional grid-connected control strategy (grid-connected type). After the two types of units are combined through a transformer substation and collection lines, they are connected to the low-voltage side busbar of the power station's step-up substation, forming a typical "grid-connected and grid-building hybrid" power plant.

[0032] The collection terminal voltage, generator terminal voltage, active power, and reactive power of grid-connected and grid-connected units can be obtained in real time through existing measuring devices at the power station (such as voltage transformers, current transformers, and power transmitters). The equivalent impedance of grid-connected and grid-connected units, the system equivalent voltage source parameters, and the equivalent impedance of the low-voltage side of the main transformer are usually not directly measurable and need to be calibrated in advance as known system inherent parameters or obtained through offline parameter identification, and then used as constants in subsequent equations. Among these, the reactive power of grid-connected units is both a controlled variable and can be monitored in real time during the dynamic process; it, along with the collection terminal voltage, serves as a key input for determining the operating status.

[0033] When constructing the system model, firstly, the power plant collection terminal is taken as the key node. The system's equivalent voltage source, the low-voltage side impedance of the main transformer, and the equivalent grid-connected and grid-connected unit branches are considered as branches connected to this node. Then, based on Kirchhoff's current law, the current balance equation of the collection terminal node is established, and the voltage-current relationship of each branch is substituted (where the grid-connected unit branch is usually represented as a controlled current source or impedance model, and the grid-connected unit branch is represented as a controlled voltage source series impedance model). Next, in a synchronous rotating coordinate system (dq axis), the AC quantities are decomposed into direct-axis and quadrature-axis components, and the time-domain equations are transformed into algebraic equations suitable for steady-state or quasi-steady-state analysis using coordinate transformation. Finally, by solving the simultaneous equations, an explicit mathematical relationship is derived with the d-axis and q-axis currents of the collection terminal as dependent variables, and the collection terminal voltage, the voltage and power of the two types of units, and the system impedance as independent variables. Thus, an analytical model for characterizing the electrical coupling characteristics of the system, i.e., the system model, is constructed.

[0034] The system model can be understood as a mathematical network describing the electrical relationships within a power plant. It uses a series of equations to clearly illustrate how the magnitude and direction of the current at the collection point (i.e., the d-axis and q-axis currents) are determined by multiple factors throughout the system. These factors include the voltage level at the collection point itself, the voltages and active and reactive power outputs of the two types of generators, and the various equivalent impedances along the path from the generators to the collection point and then to the grid. This model is similar to a calculator or mapping table; by inputting the current voltage, power, and known impedance parameters, it can accurately calculate the current state at the collection point, thus providing the crucial data foundation for subsequent assessments of the existence of harmful reactive power circulation.

[0035] The d and q axes refer to the two orthogonal coordinate axes used for analyzing and controlling AC electrical quantities in a synchronous rotating coordinate system. The d-axis (direct axis) is typically aligned with the direction of the reference voltage vector, while the q-axis (quadrature axis) leads the d-axis by 90 degrees.

[0036] S12: Based on the system model, construct an operating area map with the goal of whether reactive power circulation occurs. The horizontal axis of the operating area map represents the collection terminal voltage and includes the collection terminal voltage change threshold. The vertical axis represents the second reactive power of the grid-type unit. The operating area map includes the first reactive power limit and the second reactive power limit. The area corresponding to the first reactive power limit and the second reactive power limit is used to indicate that reactive power circulation does not occur.

[0037] In the specific construction process, firstly, based on the system model, mathematical derivation is performed with the constraint of no reactive power circulation, resulting in two key curve equations describing the safe operation boundary, namely the first reactive power limit (q). 2a ) and the second reactive power limit (q) 2bBoth are expressed as the collection terminal voltage (V). m The function is ). Simultaneously, the critical voltage value, i.e., the threshold voltage change at the collection terminal (V), is calculated based on system parameters (such as active power and equivalent impedance). m_set Then, using the pooling terminal voltage (V) m Establish a plane coordinate system with q1 as the x-axis and the reactive power of the grid-type unit (q2) as the y-axis, and plot the two boundary curves (q1, q2, q3, q4, q5, q6, q7, q8, q9, q1 ...2, 2a (V m ) and q 2b (V m )) and threshold vertical line (V m =V m_set The data is plotted in this coordinate system. Ultimately, these two curves and the threshold line divide the graph into clearly defined "safe areas" and "risk areas," thus forming an operational area diagram that can be used to intuitively assess the operational status.

[0038] The above constraint of "no reactive current circulation" is reflected in the mathematical derivation as requiring that the reactive power output of grid-connected and grid-connected units at the collection end should not form a continuous reactive current circulation in the electrical circuit between them due to conflicting control objectives. Specifically, in the model equations, this requires that the specific electrical quantities characterizing the circulation phenomenon in the system model (such as the reactive current difference between the two unit branches or the corresponding circuit voltage difference) be zero or below a certain safety threshold. By substituting this physical constraint into the system equations for analytical solution, it can be derived that for this constraint to hold, the key operating variables (such as the reactive power q2 of the grid-connected unit and the collection end voltage V) must be zero. m The mathematical relationship that must be satisfied is the boundary equation for safe operation, thus providing a strict mathematical basis for dividing the safe zone.

[0039] Figure 2 This is a schematic diagram of the operating area in an embodiment of this application. See also... Figure 2 As shown in the figure, the two curves (q) 2a With q 2b ) and a vertical line (V) m =V m_set The coordinate plane is divided into different regions. The striped areas represent safe operating zones; values ​​falling within these zones (V...) m ,q2) The operating point will not cause reactive power circulation. The non-striped area is the risk area, where the operating point may generate circulation.

[0040] When using a regional operation map for judgment, the current V is determined based on real-time measurements or scheduling plans. mPlot the corresponding operating point on the graph using the q2 value. If the point is within the stripe area, the current state is safe. If the point falls outside the stripe area, it indicates a circulating current risk, and operating parameters need to be adjusted (such as changing the voltage regulation target or the unit's reactive power output) to move the operating point into the stripe area, thereby avoiding circulating current and ensuring the safe and stable operation of the system.

[0041] S13: If the collection terminal voltage regulation value is greater than or equal to the collection terminal voltage change threshold, then determine whether the second reactive power of the grid-type unit is above the first reactive power limit and within the area formed to the right of the second reactive power limit; if the collection terminal voltage regulation value is less than the collection terminal voltage change threshold, then determine whether the second reactive power of the grid-type unit is below the first reactive power limit and within the area formed to the left of the second reactive power limit.

[0042] See also Figure 2 Combined with boundary equations q 2a and q 2b The relationship between them (usually) q 2b lie in q 2a (Bottom or right side, forming two non-intersecting curves), the specific judgment is as follows: When the collection terminal voltage adjustment value V m_ref ≥ V m_set At that time, the safe zone in the operating area diagram is q 2a Above the curve and q 2b The overlapping portion on the right side of the curve. Therefore, determine the current running point ( V m , q 2) Whether it is safe or not requires the following conditions to be met simultaneously: q 2> q 2a ( V m (Located above the first reactive power limit); The running point is at q 2b The right side of the curve (usually means) V m Larger or q 2. Under certain conditions, specifically by q 2b (Determined by the function).

[0043] when V m_ref < Vm_set At that time, the safe zone is located q 2a Below the curve and q 2b The common region to the left of the curve. At this point, we need to determine: q 2< q 2a ( V m (Located below the first reactive power limit); The running point is at q 2b To the left of the curve.

[0044] The essence of this judgment logic is to select the corresponding safe area for matching based on the different threshold ranges where the voltage regulation target is located, so as to ensure that the current operating point is located in the corresponding area, thereby avoiding reactive power circulation.

[0045] The terms "above / below" and "left / right" above refer to the relative positional relationship on the plane of the operating area map, with the curve as a reference. The purpose is to determine the operating point. V m , q 2) Whether it falls within the stripe safety area. If the corresponding conditions are met, it is considered safe; otherwise, it is unsafe.

[0046] S14: If the determination is yes, output the safety instruction.

[0047] S15: If the determination is negative, output an unsafe instruction.

[0048] If so, it means the current system operating point (collector voltage) V m Reactive power of grid-connected units q The combination of 2 is located within the safe area (striped area) of the operating area diagram, satisfying the constraint condition of "no reactive circulating current", and the system is in a stable and safe operating state.

[0049] The safety instructions must include safety confirmation information for the current operating status, such as: "Operating status is safe, no adjustment required" or "Permission to continue executing the current AVC voltage regulation instruction is allowed," and can include the safety judgment result (such as "safety flag = 1") and key operating parameters ( V m , q (2) The data is sent to the site monitoring system or energy management system for recording, display, or as input for other advanced application functions.

[0050] If not, it means that the current operating point is outside the safe zone, which poses a risk of reactive power circulation. The system may face threats such as equipment overload, increased losses, protection malfunctions, and even decreased stability.

[0051] Unsafe instructions must include explicit risk warning information, such as: "Reactive current circulation risk detected, adjustment of operating parameters recommended," and must include at least: a risk type identifier (e.g., "circulation risk"), and the coordinates of the current operating point (…). V m , q 2) Recommended adjustment direction (e.g., "It is recommended to lower...") q 2" or "Recommendation for adjustment" V m The system can be configured with a set value and may include a risk level assessment so that operators or automated control systems can take timely intervention measures to guide the system back to a safe area.

[0052] Safety or unsafe commands can be transmitted in real time via communication interfaces to the site's Energy Management System (EMS), AVC system, wind turbine main controller, reactive power compensation device (such as Static Var Generator (SVG)) controller, and central control center or dispatch master station. By integrating with these systems, commands can trigger coordinated control. The EMS can optimize power distribution across the entire site based on the commands. The AVC system can adjust voltage setpoints or switch control modes. Wind turbine and SVG controllers can adjust reactive power output in real time to avoid circulating current. The central control center can perform remote monitoring and intervention. This multi-system linkage achieves a complete link from risk warning to closed-loop control, significantly enhancing the coordination and safety of hybrid site operation.

[0053] As described above, the operation control method for hybrid power plants in this application provides a clear criterion for reactive power circulation risk assessment by establishing a precise system model and constructing an operation area map with the collection terminal voltage and reactive power of the grid-connected units as coordinates. This allows for real-time determination of whether the current operating point is within a safe zone during Automatic Voltage Control (AVC) adjustments, based on the relationship between the collection terminal voltage target value and the threshold. This enables early identification and warning of reactive power circulation risks that may lead to equipment overload, increased losses, or even system instability. By outputting corresponding safe or unsafe commands, the method guides operators or the automatic control system to take preventative adjustments, effectively avoiding circulation problems caused by control mode conflicts and significantly improving the overall operational safety and stability of the hybrid power plant.

[0054] Furthermore, as a response to Figure 1As a refinement and extension of the method shown, this application embodiment also provides an operation control method for a hybrid unit in a power plant.

[0055] Figure 3 This is a flowchart illustrating the operation control method of the hybrid unit in the power plant in this application embodiment. Figure 2 See Figure 3 As shown, the method may include: S31: Standardize the following data: the collection terminal voltage in the power plant, the first terminal voltage, first active power, first reactive power and first equivalent impedance of each grid-connected unit, the second terminal voltage, second active power, second reactive power and second equivalent impedance of each grid-connected unit, the system equivalent voltage source, the equivalent impedance of the low-voltage side of the main transformer and the reactive power output of the reactive power compensation device.

[0056] In actual power plants, even units of the same type may have different output parameters (P and Q) and slight variations in terminal voltage due to differences in local wind speed, sunlight, equipment status, or control settings. Parameters such as transformers, wiring reactors, and filters may also differ, or there may be design variations. Therefore, per-unit standardization is performed for each unit, preserving its unique operating status and electrical parameters. This allows for more accurate reflection of the actual electrical characteristics of the entire power plant under current operating conditions during subsequent network equivalence and power flow calculations using a unified reference system. This provides a more reliable data foundation for system stability analysis, fault calculation, and protection setting.

[0057] Per-unit scaling is a dimensionless method commonly used in power system analysis. It expresses all physical quantities (such as voltage, current, power, impedance, etc.) as a ratio to a selected reference value.

[0058] S32: Equip multiple grid-connected generator units and reactive power compensation devices into one grid-connected generator unit to obtain the first terminal voltage, first active power, first reactive power, and first equivalent impedance corresponding to one grid-connected generator unit; Equip multiple grid-forming generator units into one grid-forming generator unit to obtain the second terminal voltage, second active power, second reactive power, and second equivalent impedance corresponding to one grid-forming generator unit.

[0059] When equating the system to a single grid-connected unit, firstly, the per-unit active and reactive power of all grid-connected units are algebraically summed to obtain the first total active and reactive power of the equivalent unit. Simultaneously, the per-unit reactive power output from all reactive power compensation devices is also incorporated into this total reactive power. Secondly, these grid-connected units and reactive power compensation devices are connected to a common collection point (such as the low-voltage busbar of the main transformer) through their respective equivalent impedances. The first terminal voltage is then taken as the per-unit voltage of this collection point. Finally, using the parallel impedance method, the equivalent impedances of all grid-connected units are paralleled and equalized with the relevant impedances of the reactive power compensation devices to obtain the first equivalent impedance looking from this collection point to the equivalent power source. Thus, multiple dispersed devices and units are simplified into a single grid-connected unit model with aggregated power and aggregated impedance.

[0060] When equating a single grid-type generating unit, the core concept lies in constructing an equivalent voltage source with identical external characteristics at the point of common coupling. First, given the convergence point voltage, each grid-type generating unit is considered an independent voltage source connected in series with its equivalent impedance in an equivalent circuit. The output currents of all grid-type generating units (calculated based on their respective active power, reactive power, and terminal voltage) are vector-summed to obtain the total output current of the equivalent unit. Then, based on the convergence point voltage and this total current, the amplitude and phase angle of the internal voltage sources of the equivalent unit are calculated in reverse, thereby determining the second terminal voltage (usually referring to the no-load potential or equivalent terminal voltage of the equivalent voltage source). The second active power and the second reactive power are the per-unit sum of the total active and reactive power of all grid-type generating units. Finally, the equivalent impedances of all grid-type generating units are connected in parallel to obtain the second equivalent impedance looking from the convergence point towards the aggregated power supply of all grid-type generating units. Thus, multiple dispersed devices and units are simplified into a single grid-type unit model with aggregated power and aggregated impedance.

[0061] S33: Based on the collection terminal voltage in the power plant, the second terminal voltage, second active power, second reactive power and second equivalent impedance of a grid-connected unit, the first terminal voltage, first active power, first reactive power and first equivalent impedance of a grid-connected unit, the system equivalent voltage source and the equivalent impedance of the low-voltage side of the main transformer, the nodal power flow equations are used to establish the system model.

[0062] The difference between the equivalent system model and the detailed system model constructed using data from each device before equivalence lies in the trade-off between complexity and applicability. The equivalent model significantly reduces the number of nodes and equation dimension by aggregating a large number of dispersed, similar devices into a few (or even one) equivalent units and branches, resulting in an order-of-magnitude reduction in computational load. This is particularly suitable for scenarios requiring rapid solutions or repeated scans, such as system-level steady-state power flow calculations, short-circuit capacity analysis, and initial stability assessments. While sacrificing details of dynamic interactions and local inhomogeneities between devices within the plant, and making it unsuitable for analyzing refined issues such as circulating currents and subsynchronous oscillations between units, its macroscopic electrical characteristics (such as total power at the grid connection point, voltage level, and contribution to external short-circuit current) are effectively preserved under high accuracy requirements, thus achieving an optimal balance between computational efficiency and engineering practicality.

[0063] Specifically, step S33 above may include: S331: Substitute the collection terminal voltage in the power plant, the second terminal voltage, second active power, second reactive power and second equivalent impedance of a grid-connected unit, the first terminal voltage, first active power, first reactive power and first equivalent impedance of a grid-connected unit, the system equivalent voltage source and the equivalent impedance of the low-voltage side of the main transformer into the nodal power flow equation.

[0064] In the specific substitution process, each electrical branch in the system (including equivalent grid-type unit branches, equivalent grid-connected unit branches, main transformer branches, and system equivalent power supply branches) is regarded as a complex power source or impedance path that "injects" or "flows out" from the collection node. The current (or power) generated by each branch at the collection node is expressed by its corresponding known parameters (such as terminal voltage, active / reactive power, equivalent impedance, etc.). These current expressions are then substituted into the node power flow equations that describe the sum of the currents at the collection node as zero, thereby constructing a set of equations with the collection voltage as the core unknown and including all known parameters and operating variables.

[0065] S332: Deriving the nodal power flow equations after substitution, we get: , Among them, V m Indicates the magnitude of the collector voltage, I md I represents the d-axis current component of the grid-type generator unit. mq I represents the q-axis current component of the grid-type generator unit. 2d I represents the d-axis current component of a grid-connected unit. 2q q represents the q-axis current component of the grid-connected unit, q2 represents the second reactive power of the grid-connected unit, V1 represents the first terminal voltage of the grid-connected unit, and q 1mp1 represents the first reactive power of the grid-connected unit, p2 represents the second active power of the grid-connected unit, and X represents the first reactive power of the grid-connected unit. b q represents the system's equivalent reactance. 2m X represents the second reactive power of a grid-connected unit. t2 X represents the second equivalent impedance of a grid-connected unit. t1 θ represents the first equivalent impedance of the grid-connected unit, and θ represents the phase angle of the collector voltage.

[0066] In the specific derivation, the port voltage-current relationships are first established based on the circuit topology and control characteristics of the two types of units (Active Power-Voltage Control (PQ) or Active Power-Reactive Power Control (PV)). Then, all AC quantities are transformed to a dq rotating coordinate system with the system voltage as the reference through coordinate transformation, and the time-domain sinusoidal quantities are decomposed into DC quantities along the direct axis (d-axis) and quadrature axis (q-axis). Next, based on power conservation and node current balance (Kirchhoff's laws), the power equations of the unit (active power p, reactive power q) are combined with the dq-axis current, voltage, and impedance relationships. Finally, intermediate variables (such as terminal voltage phase) are eliminated through algebraic operations, and a set of equations with the dq-axis current (I) at the collection terminal is obtained. md ,I mq ,I 2d ,I 2q () is an explicit expression and includes the convergent voltage magnitude V. m Phase angle θ, unit power (p1, q) 1m p2,q 2m ) and impedance parameters (X t1 ,X t2 ,X b The complete set of equations is used to establish a system model for circulation analysis.

[0067] S34: Based on the system model, and with the presence or absence of reactive power circulation as the objective, the boundary operation equations are derived: , Where, q 2a q represents the first reactive power limit. 2b V represents the second reactive power limit. m_set V represents the threshold voltage change at the collection terminal. m X represents the magnitude of the collector voltage. b p1 represents the equivalent impedance of the low-voltage side of the main transformer, p2 represents the first active power of the grid-connected unit, and p2 represents the second active power of the grid-connected unit. t2 This represents the second equivalent impedance of a grid-type unit.

[0068] In the specific derivation, the physical conditions for the occurrence of "reactive current circulation" are first clearly defined in the system model. This is typically manifested as non-zero reactive current between parallel branches or the existence of net reactive current exchange in a specific direction. Then, this physical condition is transformed into equality or inequality constraints in the mathematical model and substituted into the previously established constraints. Vm , q 2. A system of equations relating unit power and impedance parameters. Then, through algebraic operations (such as elimination, substitution, and solving for critical conditions), the key variables are derived when the system is precisely in the critical state between "reactive current circulation" and "no reactive current circulation". q 2 and Vm The mathematical relationship that must be satisfied is used to solve for the two boundary curves. q 2 a ( Vm )and q 2 b ( Vm The analytical expression for ) is derived. Simultaneously, during the derivation process, the specific voltage critical point that causes a physical or mathematical transformation in the properties of the two boundary curves (e.g., intersection or tangency) is solved; this is the threshold voltage change at the collection terminal. Vm _ set .

[0069] S35: Construct the operating region map based on the boundary running equation.

[0070] In the specific construction, firstly, in a Cartesian coordinate system, the amplitude of the collecting terminal voltage is used as the basis. Vm The horizontal axis represents the reactive power of grid-connected units. q 2 represents the ordinate. Next, the derived boundary equations will be... q 2 a ( Vm )and q 2 b ( Vm As two function curves, and the critical voltage value Vm _ set As a straight line perpendicular to the horizontal axis, it is plotted in this coordinate system. These three lines divide the entire coordinate plane into several regions. Finally, based on the physical meaning of circulation analysis (usually verified through theoretical analysis or numerical simulation), the region enclosed by these two curves and the threshold line that satisfies... q 2 a and q 2 b Specific positional relationships (such as) q 2> q 2 a And located in q 2 bThe continuous area on the right is the "safe area" (i.e., the set of operating points where reactive power circulation does not occur), and it is clearly marked on the map (e.g., filled with stripes), thus completing the construction of an operating area map that can be used for intuitive judgment.

[0071] S36: If the collection terminal voltage regulation value is greater than or equal to the collection terminal voltage change threshold, then determine whether the second reactive power of the grid-type unit is above the first reactive power limit and within the area formed to the right of the second reactive power limit; if the collection terminal voltage regulation value is less than the collection terminal voltage change threshold, then determine whether the second reactive power of the grid-type unit is below the first reactive power limit and within the area formed to the left of the second reactive power limit.

[0072] S37: If the determination is yes, output the safety instruction.

[0073] S38: If the judgment is negative, an unsafe command is output, and the collection terminal voltage regulation value is adjusted according to the operating area diagram so that the range of the first reactive power limit and the second reactive power limit corresponding to the adjusted collection terminal voltage regulation value covers the second reactive power of the grid-type unit.

[0074] If the judgment is negative, it means that the current running point ( Vm , q 2) If the system falls within the unsafe area of ​​the operating area diagram, there is a clear risk of reactive power circulation. In addition to outputting unsafe commands, the collection terminal voltage regulation value (i.e., the voltage setting target of the AVC system) can be directly adjusted according to the operating area diagram. Vm _ ref ).

[0075] In specific adjustments, the current actual situation can be considered on the operating area map. q A value of 2 represents the horizontal reference line; find the boundary between this horizontal line and the safe zone. q 2 a and q 2 b The intersection of the curves. Then, Vm _ ref Adjust to a level that allows the safe zone boundary to cover the current area. q Within the voltage range of 2. For example: Vm _ ref Set it to be slightly higher or lower than the current value, so that in the new Vm Down, q Two values ​​can simultaneously satisfy q 2 a and q 2 b The defined safety inequality conditions ensure that the operating point is "pulled back" to the safe zone, thus preventing circulation at the source.

[0076] This concludes the description of the operation control method for the hybrid unit in the power plant provided in the embodiments of this application.

[0077] Based on the same inventive concept, this application also provides an operation control device for a hybrid unit in a power plant.

[0078] Figure 4 This is a schematic diagram of the operation control device for the combined unit in the power plant in the embodiments of this application. Figure 1 See Figure 4 As shown, the device may include: The first building module 41 is used to establish a system model based on the collection terminal voltage in the power plant, the first terminal voltage, first active power, first reactive power and first equivalent impedance of the grid-type unit, the second terminal voltage, second active power, second reactive power and second equivalent impedance of the grid-type unit, the system equivalent voltage source and the equivalent impedance of the low-voltage side of the main transformer, using nodal power flow equations. The system model is used to indicate the relationship between the dp-axis current of the collection terminal and the voltage, power and impedance.

[0079] The second construction module 42 is used to construct an operating area map based on the system model, with the goal of whether reactive power circulation occurs. The horizontal axis of the operating area map represents the collection terminal voltage and includes the collection terminal voltage change threshold. The vertical axis represents the second reactive power of the grid-type unit. The operating area map includes a first reactive power limit and a second reactive power limit. The area corresponding to the first reactive power limit and the second reactive power limit is used to indicate that reactive power circulation does not occur.

[0080] The judgment module 43 is used to determine whether the second reactive power of the grid-type unit is above the first reactive power limit and within the area to the right of the second reactive power limit if the collection terminal voltage regulation value is greater than or equal to the collection terminal voltage change threshold; and whether the second reactive power of the grid-type unit is below the first reactive power limit and within the area to the left of the second reactive power limit if the collection terminal voltage regulation value is less than the collection terminal voltage change threshold.

[0081] The first output module 44 is used to output a safety instruction if the determination is yes.

[0082] The second output module 45 is used to output an unsafe instruction if the determination is negative.

[0083] Furthermore, as a response to Figure 4 In a refinement and extension of the illustrated device, this application embodiment also provides an operation control device for a hybrid unit in a power plant.

[0084] Figure 5 This is a schematic diagram of the operation control device for the combined unit in the power plant in the embodiments of this application. Figure 2 See Figure 5 As shown, the device may include: The preprocessing module 51 is used to standardize the collection terminal voltage in the power plant, the first terminal voltage, first active power, first reactive power and first equivalent impedance of each grid-connected unit, the second terminal voltage, second active power, second reactive power and second equivalent impedance of each grid-connected unit, the system equivalent voltage source, the equivalent impedance of the low-voltage side of the main transformer and the reactive power output of the reactive power compensation device.

[0085] When there are multiple grid-connected units and multiple grid-connected units, the first construction module 52 is used to convert multiple grid-connected units and reactive power compensation devices into one grid-connected unit, obtaining the first terminal voltage, first active power, first reactive power, and first equivalent impedance corresponding to one grid-connected unit; convert multiple grid-connected units into one grid-connected unit, obtaining the second terminal voltage, second active power, second reactive power, and second equivalent impedance corresponding to one grid-connected unit; based on the collection terminal voltage in the power plant, the second terminal voltage, second active power, second reactive power, and second equivalent impedance corresponding to one grid-connected unit, the first terminal voltage, first active power, first reactive power, and first equivalent impedance corresponding to one grid-connected unit, the system equivalent voltage source, and the equivalent impedance of the low-voltage side of the main transformer, a system model is established using nodal power flow equations.

[0086] The first construction module 52 is specifically used to substitute the collection terminal voltage in the power plant, the second terminal voltage, second active power, second reactive power, and second equivalent impedance of a grid-connected unit, the first terminal voltage, first active power, first reactive power, and first equivalent impedance of a grid-connected unit, the system equivalent voltage source, and the equivalent impedance of the low-voltage side of the main transformer into the nodal power flow equations; and derive the nodal power flow equations after substitution to obtain: , Among them, V m Indicates the magnitude of the collector voltage, I md I represents the d-axis current component of the grid-type generator unit. mq I represents the q-axis current component of the grid-type generator unit. 2d I represents the d-axis current component of a grid-connected unit. 2q q represents the q-axis current component of the grid-connected unit, q2 represents the second reactive power of the grid-connected unit, V1 represents the first terminal voltage of the grid-connected unit, and q 1m p1 represents the first reactive power of the grid-connected unit, p2 represents the second active power of the grid-connected unit, and X represents the first reactive power of the grid-connected unit. b q represents the system's equivalent reactance. 2mX represents the second reactive power of a grid-connected unit. t2 X represents the second equivalent impedance of a grid-connected unit. t1 θ represents the first equivalent impedance of the grid-connected unit, and θ represents the phase angle of the collector voltage.

[0087] The second building module 53 is used to derive the boundary operation equations based on the system model, with the presence or absence of reactive power circulation as the objective: , Where, q 2a q represents the first reactive power limit. 2b V represents the second reactive power limit. m_set V represents the threshold voltage change at the collection terminal. m X represents the magnitude of the collector voltage. b p1 represents the equivalent impedance of the low-voltage side of the main transformer, p2 represents the first active power of the grid-connected unit, and p2 represents the second active power of the grid-connected unit. t2 The second equivalent impedance of the grid-type unit is represented; the operating area map is constructed based on the boundary operating equations.

[0088] The judgment module 54 is used to determine whether the second reactive power of the grid-type unit is above the first reactive power limit and within the area to the right of the second reactive power limit if the collection terminal voltage regulation value is greater than or equal to the collection terminal voltage change threshold; and whether the second reactive power of the grid-type unit is below the first reactive power limit and within the area to the left of the second reactive power limit if the collection terminal voltage regulation value is less than the collection terminal voltage change threshold.

[0089] The first output module 55 is used to output a safety instruction if the determination is yes.

[0090] The second output module 56 is used to output an unsafe command if the determination is negative, and to adjust the collection terminal voltage regulation value according to the operating area diagram, so that the range of the first reactive power limit and the second reactive power limit corresponding to the adjusted collection terminal voltage regulation value covers the second reactive power of the grid-type unit.

[0091] It should be noted that the descriptions of the above device embodiments are similar to those of the above method embodiments, and have similar beneficial effects. For technical details not disclosed in the device embodiments of this application, please refer to the descriptions of the method embodiments of this application for understanding.

[0092] Based on the same inventive concept, this application also provides a computer device.

[0093] Figure 6 This is a schematic diagram of the structure of the computer device in an embodiment of this application. See also... Figure 6As shown, the computer device may include: a memory 61, a processor 62, and a computer program stored on the memory 61, wherein the processor 62 executes the computer program to implement the methods described in the foregoing embodiments.

[0094] It should be noted that the description of the above computer device embodiments is similar to the description of the above method embodiments, and has similar beneficial effects. For technical details not disclosed in the computer device embodiments of this application, please refer to the description of the method embodiments of this application for understanding.

[0095] Based on the same inventive concept, embodiments of this application also provide a computer-readable storage medium. The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the methods described in the foregoing embodiments.

[0096] It should be noted that the description of the above computer-readable storage medium embodiments is similar to the description of the above method embodiments, and has similar beneficial effects. For technical details not disclosed in the computer-readable storage medium embodiments of this application, please refer to the description of the method embodiments of this application for understanding.

[0097] Based on the same inventive concept, this application also provides a computer program product. The computer program product includes a computer program that, when executed by a processor, implements the methods described in the foregoing embodiments.

[0098] It should be noted that the descriptions of the above computer program product embodiments are similar to those of the above method embodiments, and have similar beneficial effects. For technical details not disclosed in the computer program product embodiments of this application, please refer to the descriptions of the method embodiments of this application for understanding.

[0099] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for operating and controlling a hybrid unit in a power plant, characterized in that, The method includes: Based on the collection terminal voltage in the power plant, the first terminal voltage, first active power, first reactive power and first equivalent impedance of the grid-type unit, the second terminal voltage, second active power, second reactive power and second equivalent impedance of the grid-type unit, the system equivalent voltage source and the equivalent impedance of the low-voltage side of the main transformer, the nodal power flow equations are used to establish the system model, wherein the system model is used to indicate the relationship between the dp-axis current of the collection terminal and the voltage, power and impedance; Based on the system model, an operating area map is constructed with the goal of whether reactive power circulation occurs. The horizontal axis of the operating area map represents the collection terminal voltage and includes a collection terminal voltage change threshold. The vertical axis represents the second reactive power of the grid-type unit. The operating area map includes a first reactive power limit and a second reactive power limit. The area corresponding to the first reactive power limit and the second reactive power limit is used to indicate that reactive power circulation does not occur. If the collection terminal voltage regulation value is greater than or equal to the collection terminal voltage change threshold, then it is determined whether the second reactive power of the grid-type unit is above the first reactive power limit and within the area formed to the right of the second reactive power limit; if the collection terminal voltage regulation value is less than the collection terminal voltage change threshold, then it is determined whether the second reactive power of the grid-type unit is below the first reactive power limit and within the area formed to the left of the second reactive power limit. If the determination is yes, then output the safety command; If the determination is negative, an unsafe instruction is output.

2. The method according to claim 1, characterized in that, Based on the system model, the operational region map is constructed with the objective of whether reactive power circulation occurs, including: Based on the system model, and taking the occurrence of reactive power circulation as the objective, the boundary operation equations are derived as follows: ， Where, q 2a q represents the first reactive power limit. 2b V represents the second reactive power limit. m_set V represents the threshold voltage change at the collection terminal. m X represents the magnitude of the collector voltage. b p1 represents the equivalent impedance of the low-voltage side of the main transformer, p2 represents the first active power of the grid-connected unit, and p2 represents the second active power of the grid-connected unit. t2 This represents the second equivalent impedance of a grid-connected unit; The operating region map is constructed based on the boundary operating equation.

3. The method according to claim 1, characterized in that, The number of grid-connected units is multiple, and the number of network-connected units is multiple; based on the collection terminal voltage in the power plant, the first terminal voltage, first active power, first reactive power, and first equivalent impedance of the grid-connected units, the second terminal voltage, second active power, second reactive power, and second equivalent impedance of the network-connected units, the system equivalent voltage source, and the equivalent impedance of the low-voltage side of the main transformer, a system model is established using nodal power flow equations, including: Multiple grid-connected generator units and reactive power compensation devices are equivalent to one grid-connected generator unit, and the first terminal voltage, first active power, first reactive power and first equivalent impedance corresponding to the one grid-connected generator unit are obtained. Multiple grid-type generator units are equivalent to one grid-type generator unit, and the second terminal voltage, second active power, second reactive power and second equivalent impedance of the one grid-type generator unit are obtained. Based on the collection terminal voltage in the power plant, the second terminal voltage, second active power, second reactive power and second equivalent impedance of the grid-connected unit, the first terminal voltage, first active power, first reactive power and first equivalent impedance of the grid-connected unit, the system equivalent voltage source and the equivalent impedance of the low-voltage side of the main transformer, the nodal power flow equations are used to establish the system model.

4. The method according to claim 3, characterized in that, Based on the collection terminal voltage in the power plant, the second terminal voltage, second active power, second reactive power, and second equivalent impedance of a grid-connected unit, the first terminal voltage, first active power, first reactive power, and first equivalent impedance of a grid-connected unit, the system equivalent voltage source, and the equivalent impedance of the low-voltage side of the main transformer, a system model is established using nodal power flow equations, including: Substitute the collection terminal voltage in the power plant, the second terminal voltage, second active power, second reactive power and second equivalent impedance of the grid-connected unit, the first terminal voltage, first active power, first reactive power and first equivalent impedance of the grid-connected unit, the system equivalent voltage source and the equivalent impedance of the low-voltage side of the main transformer into the nodal power flow equation. The nodal power flow equations after substitution are derived as follows: ， Among them, V m Indicates the magnitude of the collector voltage, I md I represents the d-axis current component of the grid-type generator unit. mq I represents the q-axis current component of the grid-type generator unit. 2d I represents the d-axis current component of a grid-connected unit. 2q q represents the q-axis current component of the grid-connected unit, q2 represents the second reactive power of the grid-connected unit, V1 represents the first terminal voltage of the grid-connected unit, and q 1m p1 represents the first reactive power of the grid-connected unit, p2 represents the second active power of the grid-connected unit, and X represents the first reactive power of the grid-connected unit. b q represents the system's equivalent reactance. 2m X represents the second reactive power of a grid-connected unit. t2 X represents the second equivalent impedance of a grid-connected unit. t1 θ represents the first equivalent impedance of the grid-connected unit, and θ represents the phase angle of the collector voltage.

5. The method according to claim 3, characterized in that, Before converting multiple grid-connected generator units and reactive power compensation devices into a single grid-connected generator unit and obtaining the first terminal voltage, first active power, first reactive power, and first equivalent impedance corresponding to the single grid-connected generator unit, the method further includes: The first terminal voltage, first active power, first reactive power, and first equivalent impedance of each grid-connected generator unit, as well as the reactive power output of the reactive power compensation device, are normalized.

6. The method according to any one of claims 1 to 5, characterized in that, The method further includes: If the determination is negative, the collection terminal voltage regulation value is adjusted according to the operating area diagram so that the range of the first reactive power limit and the second reactive power limit corresponding to the adjusted collection terminal voltage regulation value covers the second reactive power of the grid-type unit.

7. An operation control device for a hybrid unit in a power plant, characterized in that, The device includes: The first construction module is used to establish a system model based on the collection terminal voltage in the power plant, the first terminal voltage, first active power, first reactive power and first equivalent impedance of the grid-type unit, the second terminal voltage, second active power, second reactive power and second equivalent impedance of the grid-type unit, the system equivalent voltage source and the equivalent impedance of the low-voltage side of the main transformer, using nodal power flow equations. The system model is used to indicate the relationship between the dp-axis current of the collection terminal and the voltage, power and impedance. The second construction module is used to construct an operating area map based on the system model, with the goal of whether reactive power circulation occurs. The horizontal axis of the operating area map represents the collection terminal voltage and includes a collection terminal voltage change threshold. The vertical axis represents the second reactive power of the grid-type unit. The operating area map includes a first reactive power limit and a second reactive power limit. The area corresponding to the first reactive power limit and the second reactive power limit is used to indicate that reactive power circulation does not occur. The judgment module is used to determine whether the second reactive power of the grid-type unit is located above the first reactive power limit and within the area to the right of the second reactive power limit if the collection terminal voltage regulation value is greater than or equal to the collection terminal voltage change threshold; and whether the second reactive power of the grid-type unit is located below the first reactive power limit and within the area to the left of the second reactive power limit if the collection terminal voltage regulation value is less than the collection terminal voltage change threshold. The first output module is used to output a safety instruction if the determination is yes; The second output module is used to output an unsafe instruction if the determination is negative.

8. 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 to 6.

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

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

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