Method for evaluating power and voltage regulation capability of a rotary power flow controller

Abstract

The application provides a power and voltage regulation capability evaluation method of a rotating power flow controller, and belongs to the technical field of power and voltage regulation capability evaluation of the rotating power flow controller; in order to accurately depict the regulation range of the RPFC, each electrical quantity data of the RPFC flexible interconnection system during operation is collected and monitored in real time, and whether the system is operated near the stability boundary is judged; if the system operating point is close to the stability boundary, the collected electrical quantity data is pretreated, and the operating boundary model corresponding to the current operating point is constructed on the PQ plane; the change of the system operating voltage is simulated, and under the premise that the safe operation margin is sufficient, the dynamic offset characteristics of the operating boundary model under different voltage levels are obtained; the regulation device is introduced, the same test conditions are kept, and the operating boundary model is constructed; the dynamic response characteristics of the operating boundary model are simulated, and the boundary expansion effect under the support of the regulation device is obtained; the application is applied to the power and voltage regulation capability evaluation of the rotating power flow controller.

Description

Technical Field

[0001] This invention provides a method for evaluating the power and voltage regulation capabilities of a rotating power flow controller, belonging to the technical field of evaluating the power and voltage regulation capabilities of rotating power flow controllers. Background Technology

[0002] In recent years, the high proportion of distributed energy grid connection and the access of diversified loads have led to the rapid expansion of the power grid. As a result, problems such as bidirectional power flow, voltage overruns, and feeder load imbalance in the distribution network have become increasingly prominent. These problems not only increase system operating losses and reduce the capacity for renewable energy absorption, but may also lead to overload of distribution equipment, seriously affecting the economic efficiency of the power grid. The traditional control method that relies on primary equipment such as on-load tap changers for network reconfiguration is limited by factors such as response time, number of switching actions, and closing inrush current, and can no longer meet the voltage control requirements in scenarios with a high proportion of renewable energy access. On the other hand, achieving load balancing through direct feeder ring networks will cause new problems such as circulating power and electromagnetic ring networks.

[0003] Currently, flexible interconnection devices, represented by intelligent soft switches, power electronic transformers, and unified power flow controllers, are gradually becoming core technologies for realizing intelligent distribution network control due to their rapid response and precise control characteristics. They provide effective solutions for improving the operational flexibility of distribution networks and enhancing the absorption capacity of new energy sources. Rotary Power Flow Controllers (RPFCs), which adopt rotating phase-shifting transformer technology, are electromagnetic control devices. By dynamically adjusting voltage and power flow distribution, these devices can significantly improve the operational stability of power systems. Compared with traditional mechanical switch-type phase-shifting devices, RPFCs have obvious advantages in control accuracy and response speed, providing a new technical path for the economical operation and flexible regulation of power systems.

[0004] Existing research focuses on the topology construction and improvement methods of power compensation devices, providing cost-effective topologies for flexible distribution network interconnection. However, there is a lack of quantitative analysis of the regulation capabilities of RPFC-based flexible distribution network interconnection, resulting in an inability to effectively assess its power and voltage regulation capabilities. This makes the actual operating characteristics of RPFC unclear and hinders its practical application in flexible distribution network construction. Furthermore, in current flexible interconnection systems based on rotating power flow controllers, the lack of precise quantitative analysis of its power and voltage regulation capabilities leads to limited actual control capabilities and a conservative system operation. While existing technologies can achieve power decoupling control of RPFC, they fail to accurately characterize its regulation range and do not fully consider the impact of voltage safety constraints on its effective regulation range, making it difficult for the device to fully realize its potential performance in actual operation. Summary of the Invention

[0005] To address the technical problems existing in the background art, the present invention provides a method for evaluating the power and voltage regulation capabilities of a rotating power flow controller, comprising the following evaluation steps:

[0006] Step 1: Collect various electrical quantity data during the operation of the RPFC flexible interconnection system, including RPFC series side voltage, line current, RPFC connection point bus voltage, RPFC rotor angle, and line transmission power, and monitor these electrical quantity data in real time to determine whether the system is operating near the stability boundary.

[0007] Step 2: If the system operating point is close to the stability boundary, the electrical quantity data collected in Step 1 is preprocessed, and the operating boundary model corresponding to the current operating point is constructed on the PQ plane.

[0008] Based on this, the operating voltage of the simulated system is changed, and under the premise of sufficient safety margin, the dynamic offset characteristics of the operating boundary model under different voltage levels are obtained.

[0009] Step 3: Introduce an adjustment device to maintain the same test conditions as in Step 2 and construct a running boundary model;

[0010] Based on this, the system operating voltage changes are simulated, and under the premise of sufficient safety margin, the dynamic response characteristics of the operating boundary model are simulated to obtain the boundary expansion effect supported by the regulating device.

[0011] Step 4: Compare and analyze the RPFC operating boundary model after the introduction of the regulating device with the single RPFC operating boundary model. By calculating the indicators of operating boundary area expansion rate, critical operating point margin improvement rate, and operating boundary offset rate, the degree of improvement of the regulating device on RPFC power regulation margin, system voltage, and operating flexibility is quantified.

[0012] The specific method for step 2 is as follows:

[0013] In the single-phase equivalent circuit of RPFC, RPFC synthesizes a stator voltage phasor with constant amplitude and adjustable phase angle by rotating the rotor angle of two sets of RPST. The two sets of stator voltage phasors are superimposed to realize the injection of a series voltage with adjustable amplitude and phase angle into the line.

[0014] Define separately and For the voltage and current before connecting to the RPFC, Z rt Z is the equivalent impedance of the parallel rotor winding of RPST. RPST1 Z RPST2 These are the equivalent impedances of the series stator windings of RPST1 and RPST2, respectively. Let be the rotor-side current, k be the stator-side and rotor-side winding turns ratio, and a1 and a2 be the relative angles between the stator and rotor of the two RPSTs, respectively. The equivalent voltage of the RPFC series-inserted line. The voltage below the RPFC access point;

[0015] The relationship between the RPFC-coupled line voltage vector, grid connection point voltage, rotor angle, and equipment impedance can be expressed as:

[0016] (1);

[0017] (2);

[0018] In the formula: , ;

[0019] By changing the relative angles a1 and a2 between the stator and rotor, the voltage vector of the RPFC series line is affected, and on this basis, its power decoupling model is constructed.

[0020] Define the line impedances of busbars 1 and 2 as R1+jX1 and R2+jX2 respectively, and the load powers as P1+jQ1 and P2+jQ2 respectively. Then, the voltages on both sides of the loop switch K are respectively... and Under closed-loop operation, the current in line l3 is i, and the power flowing through the loop connection point is P3+jQ3. After the RPFC is put into operation, the active control of the line power is achieved by dynamically adjusting the amplitude ΔU and phase angle θ of the series injection voltage. Based on instantaneous power theory, the calculation formulas for the active power P3 and reactive power Q3 at the RPFC connection point are as follows:

[0021] (3);

[0022] Under the condition that ωL>>R is satisfied inside the RPFC, the dq-axis component U of the RPFC output voltage is obtained. RPFCd U RPFCq The relationship between the power of the RPFC access point and the power is expressed as:

[0023] (4);

[0024] U RPFCd and U RPFCq The dq-axis components of the RPFC output voltage have the following relationship in phasor form:

[0025] (5);

[0026] After the system is connected to the RPFC, the adjustment range of the node power is determined by the output voltage. and grid connection point voltage Composition, maximum output voltage U RPFCmax with U RPFCd U RPFCq It has the following constraints:

[0027] (6);

[0028] Based on the above constraints and U RPFCd U RPFCq The relationship between the RPFC access point power and the RPFC power operating range and grid connection point voltage is obtained. RPFC output voltage dq-axis component, voltage below the connection point The constraints between them satisfy:

[0029] (7);

[0030] The above constraints are used to construct the running boundary model corresponding to the current running point on the PQ plane.

[0031] The safety margin in steps 2 and 3 is specifically as follows:

[0032] Combination and The safe operating conditions are defined by the expression for the RPFC safety margin as follows:

[0033] (8);

[0034] When 0 < When the voltage is less than 5%, the system enters a voltage over-limit risk state. When the voltage is less than 0, the system voltage exceeds the limit.

[0035] In step 4:

[0036] The calculated operating boundary area expansion rate is specifically defined as the increase in the area enclosed by the RPFC operating boundary on the PQ plane relative to the original boundary area after the introduction of the adjustment device.

[0037] The calculated critical operating point margin improvement rate is specifically the relative improvement rate of the RPFC's safe operating margin before and after introducing the regulating device at the rated power point and the limit transmission point;

[0038] The calculated operating boundary offset rate is specifically: the operating boundary offset caused by the change in grid connection point voltage. The operating boundary offset is simulated before and after the introduction of the regulating device under the premise of sufficient safe operating margin, and their maximum operating boundary center offset rate is compared.

[0039] The advantages of this invention compared to existing technologies are as follows: This invention provides a method for evaluating the power and voltage regulation capabilities of a rotating power flow controller (RPFC). Based on the RPFC power decoupling control model, it accurately characterizes the RPFC operating boundary and defines its safe operating margin considering voltage constraints, thus providing a theoretical basis and criterion support for its reliable operation in complex distribution network environments. Furthermore, it introduces a typical reactive power control device (SVC) and systematically analyzes its dynamic influence mechanism on the RPFC operating boundary. Finally, by constructing a generalized operating boundary for the coordinated operation of RPFC and SVC, it expands the applicability of this operating boundary analysis method in multiple distribution network scenarios, providing a complete technical path for improving system regulation margin and ensuring safe voltage operation. This invention characterizes the operating boundary based on the RPFC's power regulation capability and defines the safe operating margin based on voltage offset, providing a scientific decision-making reference for the practical application of RPFC in distribution network optimization. Attached Figure Description

[0040] The present invention will be further described below with reference to the accompanying drawings:

[0041] Figure 1 This is the equivalent circuit diagram of the RPFC of the present invention;

[0042] Figure 2 This is a diagram of the network structure for the closed-loop operation of the petal-shaped distribution network of the present invention;

[0043] Figure 3 This is a diagram illustrating the effect of different RPFC capacities on the operating boundary of the present invention.

[0044] Figure 4 This is a diagram illustrating the effect of power regulation boundary changes in the RPFC when the voltages at both nodes change in an embodiment of the present invention.

[0045] Figure 5 This is a diagram illustrating the power operation boundary analysis of the SVC access RPFC interconnect system in an embodiment of the present invention.

[0046] Figure 6 This is a flowchart illustrating the steps of the method for evaluating the power and voltage regulation capabilities of the rotating power flow controller of the present invention. Detailed Implementation

[0047] like Figures 1 to 6 As shown, this invention provides a method for evaluating the power and voltage regulation capabilities of a rotating power flow controller (RPFC), involving configuration and evaluation technology in the scenario of flexible interconnection of distribution networks. It measures the power and voltage regulation capabilities of the RPFC by characterizing its operating boundaries and safety margins, and uniformly transforms the influence of introduced regulation devices into a quantitative impact on the RPFC's operating boundary morphology and safety margins. The method mainly includes the following evaluation steps:

[0048] Step 1, Data Acquisition and Operational Status Monitoring: Collect various electrical quantity data during the operation of the RPFC flexible interconnection system, including RPFC series side voltage, line current, RPFC connection point bus voltage, RPFC rotor angle, and line transmission power. Monitor these electrical quantities in real time to determine whether the system is operating near the stability boundary.

[0049] Step 2, Operating Boundary Modeling and Feature Analysis: If the system operating point is close to the stability boundary, preprocess the electrical quantity data collected in Step 1 and draw the operating boundary corresponding to the current operating point on the PQ plane. Based on this, simulate the change in system operating voltage, ensuring sufficient safety margin ( Under the premise of >5%), the dynamic offset characteristics of the operating boundary under different voltage levels were obtained.

[0050] Step 3, Control System Construction and Boundary Verification: Introduce an adjustment device, maintain the same test conditions as in Step 2, and draw the operating boundaries. Based on this, simulate changes in the system's operating voltage, ensuring sufficient safety margin ( Under the premise of >5%), simulate the dynamic response characteristics of the operating boundary to obtain the boundary expansion effect supported by the adjustment device.

[0051] Step 4, Evaluation: Establish a complete evaluation system, compare and analyze the RPFC operating boundary after the introduction of the regulating device with the single RPFC operating boundary, and quantify the degree of improvement of the regulating device on the RPFC power regulation margin, system voltage and operating flexibility by calculating evaluation indicators such as boundary area increment and critical operating point margin improvement rate.

[0052] Furthermore, the evaluation indicators specifically include:

[0053] Operating boundary area expansion rate: The rate at which the area enclosed by the RPFC operating boundary on the PQ plane increases relative to the original boundary area after the introduction of the adjustment device.

[0054] Critical operating point margin improvement rate: The relative improvement rate of RPFC safety operating margin before and after the introduction of the regulating device at specific critical operating points (such as rated power point, limit transmission point).

[0055] Operating boundary offset rate: The operating boundary offset is caused by the change in grid connection point voltage. The operating boundary offset is simulated before and after the introduction of the regulating device under the premise of sufficient safe operating margin, and their maximum operating boundary center offset rate is compared.

[0056] Furthermore, before preprocessing the electrical quantity data collected in step 1, the present invention needs to characterize the operating boundary of RPFC and define the safety margin.

[0057] like Figure 1 The diagram shows the single-phase equivalent circuit of an RPFC. The Rotary Phase Shifting Transformer (RPST) is the core component of the RPFC. The RPFC synthesizes a stator voltage phasor with constant amplitude and adjustable phase angle by rotating the rotor angles of two sets of RPSTs. The two sets of stator voltage phasors are superimposed to inject a series voltage with adjustable amplitude and phase angle into the circuit. and These represent the voltage and current before connecting to the RPFC, Z. rt Z is the equivalent impedance of the parallel rotor winding of RPST. RPST1 Z RPST2 These are the equivalent impedances of the series stator windings of RPST1 and RPST2, respectively. Let be the rotor-side current, k be the stator-side and rotor-side winding turns ratio, and a1 and a2 be the relative angles between the stator and rotor of the two RPSTs, respectively. The equivalent voltage of the RPFC series-inserted line. This refers to the voltage below the RPFC access point.

[0058] The relationship between the RPFC series-coupled line voltage vector, grid connection point voltage, rotor angle, and equipment impedance can be expressed as:

[0059] (1);

[0060] (2);

[0061] In the formula: , .

[0062] From equation (1), it can be concluded that the magnitude of the voltage vector inserted into the line by the RPFC is determined by cosd, and the phase angle of the voltage vector inserted into the line by the RPFC is determined by e. jj Therefore, by changing the values ​​of a1 and a2, the voltage vector of the RPFC series line can be directly affected, and based on this, its power decoupling model can be constructed.

[0063] like Figure 2 As shown, the impedances of busbars 1 and 2 are R1+jX1 and R2+jX2, respectively, and the load powers are P1+jQ1 and P2+jQ2, respectively. At this time, the voltages on both sides of the loop switch K are... and Under closed-loop operation, the current in line l3 is i, and the power flowing through the closing point is P3+jQ3.

[0064] After the RPFC is put into operation, active control of the line power is achieved by dynamically adjusting the amplitude ΔU and phase angle θ of the series injection voltage. Based on instantaneous power theory, the active power P3 and reactive power Q3 at the RPFC connection point can be calculated by the following formulas:

[0065] (3);

[0066] Under the condition that ωL>>R is satisfied inside the RPFC, the dq-axis component U of the RPFC output voltage can be derived. RPFCd U RPFCq Relationship with RPFC access point power:

[0067] (4);

[0068] U RPFCd and U RPFCq The dq-axis components of the RPFC output voltage have the following relationship in phasor form:

[0069] (5);

[0070] After the system is connected to the RPFC, the adjustment range of the node power consists of two parts, one of which comes from the output voltage. The other part is determined by the grid connection point voltage. Provided. Among them, the maximum output voltage U RPFCmax with U RPFCd U RPFCq It has the following constraints:

[0071] (6);

[0072] As can be seen from Equation (4), the grid connection point voltage and the RPFC output voltage are interrelated. By combining Equation (6), the operating range of the RPFC power and the grid connection point voltage can be obtained. RPFC output voltage dq-axis component, voltage below the connection point The following relationship must be satisfied:

[0073] (7);

[0074] At this time, combined and The safe operating conditions can be used to define the safety margin of RPFC:

[0075] (8);

[0076] When 0 < When the voltage is less than 5%, the system enters a voltage over-limit risk state. When the voltage is less than 0, the system voltage exceeds the limit.

[0077] From equation (7), we can obtain the following: Figure 3 The following table shows the influence of different RPFC capacities (output voltage vectors) on the regulated power. The boundary of the power regulation of the connected two nodes is determined by the maximum capacity of the RPFC. Under the premise that the system operating state remains unchanged, the active and reactive power can be independently adjusted within the capacity range. The adjustment results are shown in Table 1 below.

[0078] Table 1 RPFC Runtime Boundary Analysis

[0079]

[0080] Figure 4 The figure shows the change in the power regulation boundary of the RPFC when the voltages at both nodes change. It can be seen that the boundary changes as the system operating state changes. Combining equation (7), we can conclude that... The change caused the center of the node injected power to shift, and The change will simultaneously cause the center of the circle to shift and the radius to increase or decrease.

[0081] Depend on Figure 3 , 4 It can be concluded that the operating boundary of the RPFC is affected by both the system voltage state and the RPFC output voltage. By introducing SVC to supplement reactive power, the operating boundary of the RPFC can be effectively expanded, improving its regulation performance; at the same time, it also helps to improve node voltage deviation, providing a more ideal voltage level for the RPFC.

[0082] In embodiments of the present invention, the impact of RPFC power and voltage regulation capability based on operating boundaries is analyzed:

[0083] Through its dynamic reactive power compensation mechanism, the SVC enables the RPFC's regulation capacity to focus on active power, effectively improving the RPFC's operating boundary. Therefore, this invention uses the SVC as an example to verify the impact of the introduced regulation device on the RPFC's power and voltage regulation capabilities through operating boundary verification.

[0084] like Figure 5 As shown in section a, the original RPFC's operating boundary is circular. The SVC, through dynamic reactive power compensation, effectively shares the reactive power regulation burden of the RPFC, allowing its capacity resources to be redistributed and concentrated on active power regulation. Under ideal operating conditions, this operating boundary approaches a square, where the SVC bears all reactive power support, and the RPFC maximizes active power transmission. The system ultimately exhibits an active-reactive power regulation range far exceeding what can be achieved when operating independently, thus effectively improving the RPFC's power regulation margin.

[0085] like Figure 5As shown in part b, fluctuations in node voltage can cause changes in the radius and center of the RPFC operating boundary. Therefore, voltage regulation capability is crucial to ensuring the power regulation capability of the RPFC. Equation (8) defines the safe operating margin of the RPFC, reflecting the system's ability to avoid voltage over-limit risks. Introducing SVC at the grid connection point of the RPFC constitutes an effective active voltage control method. By providing rapid, bidirectional reactive power to the system, SVC can dynamically stabilize the receiving-end voltage of the RPFC within a narrower ideal range, stabilizing the voltage reference U1 of the safe operating margin, thereby expanding the safe operating domain of the RPFC, significantly reducing the risk of voltage over-limit, and avoiding the degradation of the RPFC operating boundary.

[0086] like Figure 5 As shown in parts c and d, during the process of the grid connection point voltage amplitude disturbance increasing from -0.06 pu to 0.04 pu, the active power regulation range of the RPFC shifts from [-2.2, 1.2] Mvar and expands to [-2.5, 1.5] Mvar, while the reactive power regulation range shifts from [-2.1, 1.5] Mvar and expands to [-1.4, 2.6] Mvar. The bidirectional active power regulation capability and forward reactive power regulation capability of the RPFC gradually become stronger, while the reverse reactive power regulation capability gradually weakens. However, after the introduction of SVC, its instantaneous reactive power compensation suppresses the voltage amplitude shift, thus enabling the RPFC to maintain its original operating boundaries.

[0087] This invention aims to provide a theoretical basis and criterion for the reliable operation of RPFCs in complex distribution network environments by accurately characterizing the RPFC operating boundary and defining its safety margin considering voltage constraints. Addressing the difficulty of accurately characterizing the RPFC operating boundary using traditional methods, which prevents the full utilization of the device's actual regulation capacity, this invention establishes a complete mathematical model of the operating boundary, visually presenting the safe operating area of ​​the RPFC on the PQ plane and defining a quantified safety margin index. This allows operators to accurately grasp the real-time regulation potential of the RPFC, providing a reliable basis for system optimization and scheduling. This invention overcomes the limitations of traditional single RPFC device operating boundary analysis, fully considering the complex operating conditions and multi-device coordinated control requirements in actual distribution networks. Taking SVC as an example, by uniformly transforming the influence of the introduced regulating device into a quantified impact on the RPFC operating boundary shape and safety margin, a universal "device-boundary-margin" mapping relationship is established. This analytical method allows the effectiveness of different devices to be intuitively and clearly displayed through changes in the operating boundary, greatly facilitating performance comparison and effect evaluation of various schemes. This evaluation framework has good scalability and can provide a unified performance evaluation method for the coordinated control of various flexible interconnected devices in the distribution network. It provides important technical support for the optimization planning and intelligent upgrading of the distribution network and is conducive to promoting the development of the distribution network towards a more flexible, efficient and intelligent direction.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for evaluating the power and voltage regulation capabilities of a rotating power flow controller, characterized in that: The evaluation steps include the following: Step 1: Collect various electrical quantity data during the operation of the RPFC flexible interconnection system, including RPFC series side voltage, line current, RPFC connection point bus voltage, RPFC rotor angle, and line transmission power, and monitor these electrical quantity data in real time to determine whether the system is operating near the stability boundary. Step 2: If the system operating point is close to the stability boundary, the electrical quantity data collected in Step 1 is preprocessed, and the operating boundary model corresponding to the current operating point is constructed on the PQ plane. Based on this, the operating voltage of the simulated system is changed, and under the premise of sufficient safety margin, the dynamic offset characteristics of the operating boundary model under different voltage levels are obtained. Step 3: Introduce an adjustment device to maintain the same test conditions as in Step 2 and construct a running boundary model; Based on this, the system operating voltage changes are simulated, and under the premise of sufficient safety margin, the dynamic response characteristics of the operating boundary model are simulated to obtain the boundary expansion effect supported by the regulating device. Step 4: Compare and analyze the RPFC operating boundary model after the introduction of the regulating device with the single RPFC operating boundary model. By calculating the indicators of operating boundary area expansion rate, critical operating point margin improvement rate, and operating boundary offset rate, the degree of improvement of the regulating device on RPFC power regulation margin, system voltage, and operating flexibility is quantified.

2. The method for evaluating the power and voltage regulation capability of a rotating power flow controller according to claim 1, characterized in that: The specific method for step 2 is as follows: In the single-phase equivalent circuit of RPFC, RPFC synthesizes a stator voltage phasor with constant amplitude and adjustable phase angle by rotating the rotor angle of two sets of RPST. The two sets of stator voltage phasors are superimposed to realize the injection of a series voltage with adjustable amplitude and phase angle into the line. Define separately and For the voltage and current before connecting to the RPFC, Z rt Z is the equivalent impedance of the parallel rotor winding of RPST. RPST1 Z RPST2 These are the equivalent impedances of the series stator windings of RPST1 and RPST2, respectively. Let be the rotor-side current, k be the stator-side and rotor-side winding turns ratio, and a1 and a2 be the relative angles between the stator and rotor of the two RPSTs, respectively. The equivalent voltage of the RPFC series-inserted line. The voltage below the RPFC access point; The relationship between the RPFC-coupled line voltage vector, grid connection point voltage, rotor angle, and equipment impedance can be expressed as: （1）； （2）； In the formula: , ; By changing the relative angles a1 and a2 between the stator and rotor, the voltage vector of the RPFC series line is affected, and on this basis, its power decoupling model is constructed. Define the line impedances of busbars 1 and 2 as R1+jX1 and R2+jX2 respectively, and the load powers as P1+jQ1 and P2+jQ2 respectively. Then, the voltages on both sides of the loop switch K are respectively... and Under closed-loop operation, the current in line l3 is i, and the power flowing through the loop connection point is P3+jQ3. After the RPFC is put into operation, the active control of the line power is achieved by dynamically adjusting the amplitude ΔU and phase angle θ of the series injection voltage. Based on instantaneous power theory, the calculation formulas for the active power P3 and reactive power Q3 at the RPFC connection point are as follows: （3）； Under the condition that ωL>>R is satisfied inside the RPFC, the dq-axis component U of the RPFC output voltage is obtained. RPFCd U RPFCq The relationship between the power of the RPFC access point and the power is expressed as: （4）； U RPFCd and U RPFCq The dq-axis components of the RPFC output voltage have the following relationship in phasor form: （5）； After the system is connected to the RPFC, the adjustment range of the node power is determined by the output voltage. and grid connection point voltage Composition, maximum output voltage U RPFCmax with U RPFCd U RPFCq It has the following constraints: （6）； Based on the above constraints and U RPFCd U RPFCq The relationship between the RPFC access point power and the RPFC power operating range and grid connection point voltage is obtained. RPFC output voltage dq-axis component, voltage below the connection point The constraints between them satisfy: （7）； The above constraints are used to construct the running boundary model corresponding to the current running point on the PQ plane.

3. The method for evaluating the power and voltage regulation capability of a rotating power flow controller according to claim 2, characterized in that: The safety margin in steps 2 and 3 is specifically as follows: Combination and The safe operating conditions are defined by the expression for the RPFC safety margin as follows: （8）； When 0 < When the voltage is less than 5%, the system enters a voltage over-limit risk state. When the voltage is less than 0, the system voltage exceeds the limit.

4. The method for evaluating the power and voltage regulation capability of a rotating power flow controller according to claim 3, characterized in that: In step 4: The calculated operating boundary area expansion rate is specifically defined as the increase in the area enclosed by the RPFC operating boundary on the PQ plane relative to the original boundary area after the introduction of the adjustment device. The calculated critical operating point margin improvement rate is specifically the relative improvement rate of the RPFC's safe operating margin before and after introducing the regulating device at the rated power point and the limit transmission point; The calculated operating boundary offset rate is specifically: the operating boundary offset caused by the change in grid connection point voltage. The operating boundary offset is simulated before and after the introduction of the regulating device under the premise of sufficient safe operating margin, and their maximum operating boundary center offset rate is compared.

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