A method and system for analyzing power angle stability of an ac-dc system

Abstract

The application discloses an AC-DC system power angle stability analysis method and system, relates to the technical field of power system safety and stability analysis, acquires the topological structure of an AC-DC system, performs steady-state power flow analysis on the topological structure according to preset output combination parameters, obtains initial operation parameters, and performs power angle stability margin evaluation on the system based on the initial operation parameters to obtain a thermal power unit instability interval; based on the thermal power unit instability interval, the second thermal power unit power angle and the critical cut-off power angle are determined according to the initial operation parameters; the non-periodic instability analysis is performed by using the second thermal power unit power angle, the critical cut-off power angle and the initial operation parameters to obtain the power angle stability margin evaluation value. The application solves the technical problem that the existing research does not fully consider the influence of DC control mode switching when performing AC-DC system power angle stability analysis, thereby reducing the accuracy of the AC-DC system stability margin evaluation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power system safety and stability analysis, and particularly relates to a method and system for analyzing power angle stability of an AC-DC system. BACKGROUND

[0002] With the increasing capacity of wind power, photovoltaic power, direct current and other new energy devices being connected, the coupling between AC-DC systems and between DC converter stations will be closer, and the transient stability problems of power angle and voltage caused by system faults will be more prominent, which seriously affects the safe and stable operation of the system. In the AC-DC system, the disturbance of active power may cause power angle instability. In the existing research on the power angle stability margin of the AC-DC hybrid system, the influence of the DC control mode switching in the transient process is not fully considered, resulting in low accuracy of the stability margin evaluation of the AC-DC system. SUMMARY

[0003] The present application provides a method and system for analyzing power angle stability of an AC-DC system, which solves the technical problem of low accuracy of stability margin evaluation of the AC-DC system due to insufficient consideration of the influence of DC control mode switching in the existing research on power angle stability analysis of the AC-DC system.

[0004] The first aspect of the present application provides a method for analyzing power angle stability of an AC-DC system, comprising:

[0005] Obtaining the topological structure of the AC-DC system, and performing steady-state power flow analysis on the topological structure according to the preset output combination parameters to obtain the initial operating parameters corresponding to the AC-DC system;

[0006] Performing power angle stability evaluation on the AC-DC system based on the initial operating parameters to obtain the instability interval of thermal power units;

[0007] Based on the instability interval of thermal power units, determining the second thermal power unit power angle and the critical cut-off power angle corresponding to the AC-DC system according to the initial operating parameters;

[0008] Performing non-periodic instability analysis using the second thermal power unit power angle, the critical cut-off power angle and the initial operating parameters to obtain the power angle stability margin evaluation value corresponding to the AC-DC system.

[0009] Optionally, the step of performing steady-state power flow analysis on the topological structure according to the preset output combination parameters to obtain the initial operating parameters corresponding to the AC-DC system comprises:

[0010] Constructing a DC feed-in drop point near thermal power unit simulation model using the topological structure;

[0011] inputting the preset output combination parameters into the direct current feed-in landing point near thermal power unit simulation model to obtain a target AC / DC system simulation model;

[0012] performing system power flow analysis on the target AC / DC system simulation model to obtain initial operation parameters corresponding to the AC / DC system.

[0013] Optionally, the step of performing power angle stability evaluation on the AC / DC system based on the initial operation parameters to obtain a thermal power unit instability interval includes:

[0014] inputting the initial operation parameters and characteristic parameters of the AC / DC system into a preset first power angle function to obtain a first thermal power unit power angle;

[0015] inputting the initial operation parameters and the first thermal power unit power angle into a preset thermal power unit power angle characteristic model to obtain a first thermal power unit electromagnetic power and a second thermal power unit electromagnetic power;

[0016] constructing a thermal power unit instability interval by using the first thermal power unit electromagnetic power and the second thermal power unit electromagnetic power.

[0017] Optionally, the step of determining a second thermal power unit power angle and a critical cut-off power angle corresponding to the AC / DC system according to the initial operation parameters based on the thermal power unit instability interval includes:

[0018] determining whether a thermal power unit actual output of the initial operation parameters is in the thermal power unit instability interval;

[0019] if the thermal power unit actual output is in the thermal power unit instability interval, adjusting the output combination parameters and jumping to execute the step of performing steady-state power flow analysis on the topology structure according to the preset output combination parameters to obtain the initial operation parameters corresponding to the AC / DC system;

[0020] if the thermal power unit actual output is not in the thermal power unit instability interval, performing fault cut-off analysis on the initial operation parameters by using a piecewise calculation method to obtain a second thermal power unit power angle corresponding to the AC / DC system;

[0021] inputting the second thermal power unit power angle and the initial operation parameters into a preset critical cut-off power angle function to obtain a critical cut-off power angle corresponding to the AC / DC system.

[0022] Optionally, the step of performing non-periodic instability analysis on the second thermal power unit power angle, the critical cut-off power angle and the initial operation parameters to obtain a power angle stability margin evaluation value corresponding to the AC / DC system includes:

[0023] The second thermal power unit power angle, the critical cut-off power angle and the initial operation parameter are used for power angle characteristic analysis, so that the acceleration area and the maximum deceleration area corresponding to the AC / DC system are obtained.

[0024] It is judged whether the acceleration area is greater than or equal to the maximum deceleration area.

[0025] If the acceleration area is greater than or equal to the maximum deceleration area, the output combination parameter is adjusted, and the step of performing steady-state power flow analysis on the topology according to the preset output combination parameter is executed to obtain the initial operation parameter corresponding to the AC / DC system.

[0026] If the acceleration area is less than the maximum deceleration area, the critical cut-off power angle is determined as the power angle stability margin evaluation value corresponding to the AC / DC system.

[0027] Optionally, the step of using the second thermal power unit power angle, the critical cut-off power angle and the initial operation parameter to perform power angle characteristic analysis to obtain the acceleration area and the maximum deceleration area corresponding to the AC / DC system comprises:

[0028] The critical cut-off power angle and the second thermal power unit power angle are used to construct a maximum deceleration interval.

[0029] Based on the maximum deceleration interval, the difference between the initial operation parameter of the thermal power unit output electromagnetic power and the actual output of the thermal power unit is differentiated to obtain the maximum deceleration area corresponding to the AC / DC system.

[0030] The second thermal power unit power angle and the initial power angle of the thermal power unit of the initial operation parameter are processed by difference to obtain a first difference value.

[0031] The actual output of the thermal power unit and the first difference value are multiplied to obtain the power angle acceleration area corresponding to the AC / DC system.

[0032] The second aspect of the present application provides an AC / DC system power angle stability analysis system, comprising:

[0033] The acquisition module is used for acquiring the topology structure of the AC / DC system, and performing steady-state power flow analysis on the topology structure according to the preset output combination parameter to obtain the initial operation parameter corresponding to the AC / DC system.

[0034] The stability evaluation module is used for performing power angle stability evaluation on the AC / DC system based on the initial operation parameter to obtain the thermal power unit instability interval.

[0035] An analysis module is configured to determine a second power angle of the thermal power unit corresponding to the AC-DC system and a critical cut-off power angle according to the initial operating parameters based on the instability interval of the thermal power unit;

[0036] A margin evaluation module is configured to perform aperiodic instability analysis by using the second power angle of the thermal power unit, the critical cut-off power angle and the initial operating parameters to obtain a power angle stability margin evaluation value corresponding to the AC-DC system.

[0037] The third aspect of the present application provides an electronic device including a memory and a processor, wherein the memory stores a computer program, and the computer program is executed by the processor to make the processor perform the steps of the power angle stability analysis method of the AC-DC system according to any one of the above aspects.

[0038] The fourth aspect of the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed to implement the power angle stability analysis method of the AC-DC system according to any one of the above aspects.

[0039] The fifth aspect of the present application provides a computer program product, which includes a computer program stored on a non-transitory computer readable storage medium, and the computer program includes program instructions, wherein when the program instructions are executed by a computer, the computer performs the power angle stability analysis method of the AC-DC system according to any one of the above aspects.

[0040] From the above technical solutions, the present application has the following advantages:

[0041] By obtaining the initial operating parameters of the AC-DC system, performing power angle stability margin evaluation on the system based on the initial operating parameters, obtaining the instability interval of the thermal power unit, and performing power angle stability margin evaluation on the AC-DC system according to the instability interval of the thermal power unit and the initial operating parameters, the present application realizes accurate evaluation of the power angle stability margin of the DC control, overcomes the technical problem that the existing research does not fully consider the influence of the DC control mode switching when performing power angle stability analysis of the AC-DC system, resulting in low accuracy of the stability margin evaluation of the AC-DC system. Compared with the traditional power angle stability margin evaluation method, the present application performs power angle stability margin evaluation on the AC-DC system according to the instability interval of the thermal power unit and the initial operating parameters, considers the power angle characteristics of the thermal power unit under different control strategies, determines the influence of the DC control switching on the power angle stability of the thermal power unit, realizes accurate evaluation of the AC-DC system, and improves the reliability of the AC-DC system. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only need to be some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0043] Figure 1 A step flow chart of a method for analyzing power angle stability of an AC-DC system provided by the first embodiment of the present application is shown in the figure.

[0044] Figure 2 A step flow chart of a method for analyzing power angle stability of an AC-DC system provided by the second embodiment of the present application is shown in the figure.

[0045] Figure 3 A structure schematic diagram of an LCC-HVDC system provided by the second embodiment of the present application is shown in the figure.

[0046] Figure 4 A control schematic diagram of a rectifier in the LCC-HVDC system provided by the second embodiment of the present application is shown in the figure.

[0047] Figure 5 A control schematic diagram of an inverter in the LCC-HVDC system provided by the second embodiment of the present application is shown in the figure.

[0048] Figure 6 A voltage and current characteristic curve schematic diagram corresponding to the DC control strategy provided by the second embodiment of the present application is shown in the figure.

[0049] Figure 7 A structure schematic diagram of an AC-DC system provided by the second embodiment of the present application is shown in the figure.

[0050] Figure 8 A power output curve schematic diagram of a thermal power unit under a second power output combination provided by the second embodiment of the present application is shown in the figure.

[0051] Figure 9 A power angle curve schematic diagram of a thermal power unit under a second power output combination provided by the second embodiment of the present application is shown in the figure.

[0052] Figure 10 A DC feeding point terminal voltage curve schematic diagram under a second power output combination provided by the second embodiment of the present application is shown in the figure.

[0053] Figure 11 A DC output power curve schematic diagram under a second power output combination provided by the second embodiment of the present application is shown in the figure.

[0054] Figure 12 A power output curve schematic diagram of a thermal power unit under a third power output combination provided by the second embodiment of the present application is shown in the figure.

[0055] Figure 13A schematic diagram of a power angle curve of a thermal power unit under a third output combination provided for the second embodiment of the present application;

[0056] Figure 14 A schematic diagram of a DC input point terminal voltage curve under the third output combination provided for the second embodiment of the present application;

[0057] Figure 15 A schematic diagram of a DC output power curve under the third output combination provided for the second embodiment of the present application;

[0058] Figure 16 A schematic diagram of a thermal power unit output curve under a fifth output combination provided for the second embodiment of the present application;

[0059] Figure 17 A schematic diagram of a power angle curve of a thermal power unit under the fifth output combination provided for the second embodiment of the present application;

[0060] Figure 18 A schematic diagram of a DC input point terminal voltage curve under the fifth output combination provided for the second embodiment of the present application;

[0061] Figure 19 A schematic diagram of a DC output power curve under the fifth output combination provided for the second embodiment of the present application;

[0062] Figure 20 An equivalent circuit diagram of an AC / DC system under normal conditions provided for the second embodiment of the present application;

[0063] Figure 21 An equivalent circuit diagram of an AC / DC system under fault conditions provided for the second embodiment of the present application;

[0064] Figure 22 A power angle characteristic curve of a thermal power unit considering DC control switching provided for the second embodiment of the present application;

[0065] Figure 23 A schematic diagram of a DC receiving end voltage curve during AC / DC system power angle stability analysis under a first output ratio provided for the second embodiment of the present application;

[0066] Figure 24 A schematic diagram of a power angle curve of a thermal power unit during AC / DC system power angle stability analysis under the first output ratio provided for the second embodiment of the present application;

[0067] Figure 25 A schematic diagram of a DC receiving end voltage curve during AC / DC system power angle stability analysis under a second output ratio provided for the second embodiment of the present application;

[0068] Figure 26 A schematic diagram of a power angle curve of a thermal power unit during AC / DC system power angle stability analysis under the second output ratio provided for the second embodiment of the present application;

[0069] Figure 27 A structural block diagram of a power angle stability analysis system of an AC / DC system provided by the embodiment three of the application is provided for the embodiment three of the application.

[0070] Figure 28 A structural block diagram of an electronic device provided by the embodiment four of the application is provided for the embodiment four of the application. DETAILED DESCRIPTION

[0071] The embodiment of the application provides a power angle stability analysis method and system of an AC / DC system, and is used for solving the technical problem that the influence of DC control mode switching is not fully considered when the existing research is performed on power angle stability analysis of the AC / DC system, and the accuracy of stability margin evaluation of the AC / DC system is low.

[0072] In order to make the application purpose, features and advantages of the application more obvious and easy to understand, the technical solutions in the embodiments of the application will be clearly and completely described below in combination with the drawings in the embodiments of the application. Obviously, the following described embodiments are only some of the embodiments of the application, but not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0073] Please refer to Figure 1 , Figure 1 A step flowchart of a power angle stability analysis method of an AC / DC system provided by the embodiment one of the application.

[0074] The power angle stability analysis method of the AC / DC system provided by the application comprises the following steps.

[0075] In step 101, the topological structure of the AC / DC system is acquired, and the topological structure is subjected to steady-state power flow analysis according to preset output combination parameters, so that initial operation parameters corresponding to the AC / DC system are obtained.

[0076] The AC / DC system refers to a local system of a thermal power unit near a DC feeding drop point.

[0077] The initial operation parameters refer to initial power angles of the thermal power unit, initial voltages of each node, initial active power of each branch and the like of the AC / DC system before fault, which are obtained through power flow calculation.

[0078] The output combination parameters refer to preset DC output / capacity and thermal power output / capacity.

[0079] In the embodiment of the present application, the topology structure of the AC-DC system is acquired, and the topology structure is used to construct a local simulation model of the thermal power unit near the DC feeding drop point. The preset output combination parameter is input into the local simulation model of the thermal power unit near the DC feeding drop point, and a target simulation model is obtained. The steady state power flow analysis is performed on the target simulation model, and the initial operation parameter corresponding to the AC-DC system is obtained.

[0080] In step 102, the power angle stability of the AC-DC system is evaluated based on the initial operation parameter, and a thermal power unit instability interval is obtained.

[0081] In the embodiment of the present application, the initial operation parameter and the characteristic parameter of the AC-DC system are input into a preset first power angle function, and a first thermal power unit power angle is obtained. The initial operation parameter and the first thermal power unit power angle are input into a preset thermal power unit power angle characteristic model, and a first thermal power unit electromagnetic power and a second thermal power unit electromagnetic power are obtained. The first thermal power unit electromagnetic power and the second thermal power unit electromagnetic power are used to construct the thermal power unit instability interval.

[0082] It should be noted that the first power angle function is specifically as follows:

[0083]

[0084] wherein, is the DC receiving end voltage lower than the instruction value, is the second simplified coefficient, is the third simplified coefficient, is the i-th line reactance, is the first simplified coefficient, is the first action coefficient, is the second action coefficient, is the internal potential of the thermal power unit, is the voltage of the infinite power supply, is the first thermal power unit power angle, and i is the line number.

[0085] It should be noted that the thermal power unit power angle characteristic model is specifically as follows:

[0086] Thermal power unit power angle characteristic model under normal working condition:

[0087]

[0088] Thermal power unit power angle characteristic model under fault working condition:

[0089]

[0090] wherein, is the electromagnetic power output by the thermal power unit, is the first line reactance, is the third line reactance, is a power angle of a thermal power unit, is a direct current output current, is a voltage phase angle, is a direct current receiving end voltage, is a phase angle,

[0091] In step 103, based on the instability interval of the thermal power unit, the second power angle of the thermal power unit corresponding to the AC / DC system and the critical cut-off power angle are determined according to the initial operation parameter.

[0092] The second power angle of the thermal power unit refers to the power angle of the thermal power unit at the moment of fault cut-off.

[0093] The critical cut-off power angle refers to the critical cut-off power angle of the thermal power unit.

[0094] In the embodiment of the present application, it is judged whether the actual output of the thermal power unit under the initial operation parameter is in the instability interval of the thermal power unit, when the actual output of the thermal power unit is in the instability interval of the thermal power unit, the output combination parameter is adjusted to re-execute step 101, and when the actual output of the thermal power unit is not in the instability interval of the thermal power unit, the second power angle of the thermal power unit corresponding to the AC / DC system and the critical cut-off power angle are calculated through the initial operation parameter.

[0095] In step 104, the second power angle of the thermal power unit, the critical cut-off power angle and the initial operation parameter are used for non-periodic instability analysis to obtain the power angle stability margin evaluation value corresponding to the AC / DC system.

[0096] In the embodiment of the present application, the second power angle of the thermal power unit, the critical cut-off power angle and the initial operation parameter are input into the preset power angle instability function of the thermal power unit to obtain the acceleration area and the maximum deceleration area. It is judged whether the acceleration area is greater than or equal to the maximum deceleration area, when the acceleration area is less than the maximum deceleration area, the critical cut-off power angle is determined as the power angle stability margin evaluation value corresponding to the AC / DC system.

[0097] In the embodiment of the present application, the initial operation parameter of the AC / DC system is obtained, and the power angle stability margin of the system is evaluated based on this to obtain the instability interval of the thermal power unit, and then the power angle stability margin of the AC / DC system is evaluated according to the instability interval of the thermal power unit and the initial operation parameter, so that the accurate evaluation of the power angle stability margin of the direct current control is realized, and the technical problem that the influence of the direct current control mode switching is not fully considered in the existing research when the power angle stability of the AC / DC system is analyzed, resulting in low accuracy of the stability margin evaluation of the AC / DC system is solved. Compared with the traditional power angle stability margin evaluation method, the power angle stability margin of the AC / DC system is evaluated according to the instability interval of the thermal power unit and the initial operation parameter in the present application, the power angle characteristics of the thermal power unit under different control strategies are considered, the influence of the direct current control switching on the power angle stability of the thermal power unit is clarified, the accurate evaluation of the AC / DC system is realized, and the reliability of the AC / DC system is improved.

[0098] Referring to Figure 2 , Figure 2 A step flow chart of a power angle stability analysis method of an AC-DC system is provided for Embodiment Two of the present application.

[0099] The present application provides a power angle stability analysis method of an AC-DC system, comprising:

[0100] Step 201, obtaining the topological structure of the AC-DC system, and performing steady-state power flow analysis on the topological structure according to preset output combination parameters to obtain initial operating parameters corresponding to the AC-DC system;

[0101] Further, step 201 comprises the following sub-steps:

[0102] S11, constructing a DC feeder drop point near thermal power unit simulation model using the topological structure;

[0103] In the embodiment of the present application, the topological structure of the AC-DC system is obtained, and a DC feeder drop point near thermal power unit simulation model is constructed using the topological structure.

[0104] S12, inputting the preset output combination parameters into the DC feeder drop point near thermal power unit simulation model to obtain a target AC-DC system simulation model;

[0105] In the embodiment of the present application, the model parameters of the DC feeder drop point near thermal power unit simulation model are adjusted according to the preset output combination parameters to obtain the target AC-DC system simulation model.

[0106] S13, performing system power flow analysis on the target AC-DC system simulation model to obtain initial operating parameters corresponding to the AC-DC system.

[0107] In the embodiment of the present application, system power flow analysis is performed using the target AC-DC system simulation model to obtain initial operating parameters corresponding to the AC-DC system.

[0108] It is worth mentioning that the conventional DC control strategy in the AC-DC system is specifically as follows: LCC-HVDC is selected as the research object, and the system structure is as shown in Figure 3 The control block diagram of the rectifier (Rec) is shown in Figure 4 , and the control strategy mainly includes minimum trigger angle control (CIA), constant current control (CC), and low voltage current limiting control (VDCOL). The rectifier control related parameters are shown in Table 1. The control block diagram of the inverter (Inv) is shown in Figure 5 , and the control strategy mainly includes constant extinction angle control (CEA), constant current control (CC), low voltage current limiting control (VDCOL), and current deviation control (CEC). The inverter control related parameters are shown in Table 2. The U-I characteristic curve corresponding to the LCC-HVDC DC control strategy is as shown inFigure 6 as shown.

[0109] Table 1

[0110]

[0111] Table 2

[0112]

[0113] It is worth mentioning that, referring to Figure 7 as shown, in the AC-DC system power angle instability scenario (i.e. the DC drop point near the local system power angle instability scenario of thermal power station), the system parameters are shown in Table 3. The system operation scenarios under different output ratios of conventional DC and thermal power units are constructed, a three-phase short-circuit fault is set to occur at the bus L near the Line-II line, and the Line-II line is removed after 0.1s, so as to study the possible power angle instability scenarios and the power angle stability evolution trend of the system under different output ratios of DC and thermal power.

[0114] Table 3

[0115]

[0116] Based on this local system, the conventional DC output is kept at 2700MW, and the thermal power unit output is changed, and the transient simulation results are as follows. From Table 4 and Figure 8-19 The simulation results show that when the thermal power output is low, the power angle can recover in the transient process, and there is no power angle instability phenomenon; when the thermal power output is high, the power angle of the thermal power unit will appear swing divergence instability, and when the thermal power is full load, the power angle of the thermal power unit will even appear non-synchronous instability phenomenon. It can be seen that: the connection of conventional DC weakens the damping characteristics of synchronous machines, and the higher the output ratio of synchronous machines, the worse the damping characteristics.

[0117] Table 4

[0118]

[0119] According to the above analysis, as the output ratio of thermal power units in the system increases, the thermal power units will appear power angle swing divergence instability phenomenon, and in serious cases, non-synchronous instability phenomenon will appear. The DC side voltage U di and the feed-in point voltage U W satisfy:

[0120] (1)

[0121] wherein, is the transformation ratio of the transformer between the inverter and the receiving end power grid, is the DC filter inductance. It can be seen that when the receiving end system fails, the feed-in point voltage UW decreases, leading to the DC side voltage U di decreases, the inverter control U-I characteristic curve moves downward, the DC rectifier operates in VDCOL control, and the inverter operates in CEC control mode.

[0122] In step 202, the initial operating parameters and characteristic parameters of the AC-DC system are input into a preset first power angle function to obtain a first thermal power unit power angle.

[0123] The first thermal power unit power angle refers to a thermal power unit power angle corresponding to a DC receiving end voltage equal to U WL when the DC control starts switching.

[0124] The characteristic parameters refer to inherent attribute parameters of the AC-DC system, including but not limited to line reactance and the like.

[0125] In the embodiment of the present application, the initial operating parameters and the characteristic parameters of the AC-DC system are input into the preset first power angle function, and the first power angle function is solved to obtain the first thermal power unit power angle.

[0126] In step 203, the initial operating parameters and the first thermal power unit power angle are input into a preset thermal power unit power angle characteristic model to obtain a first thermal power unit electromagnetic power and a second thermal power unit electromagnetic power.

[0127] The first thermal power unit electromagnetic power refers to a thermal power unit electromagnetic power corresponding to δ GC , that is, a thermal power angle corresponding to a control switching moment, when the DC is in control 1.

[0128] The second thermal power unit electromagnetic power refers to a thermal power unit electromagnetic power corresponding to δ GC , that is, a thermal power angle corresponding to a control switching moment, when the DC is in control 2.

[0129] It should be noted that, as shown in Figure 22 , the solid line represents a thermal power unit power angle characteristic curve when the DC control is in control 1: rectifier side constant current (CC) and inverter side constant arc extinction angle (CEA) control mode. The dotted line represents a thermal power unit power angle characteristic curve when the DC control is in control 2: low-voltage current limiting control (VDCOL) and inverter side current deviation control (CEC) mode. When the thermal power unit power angle is less than δ GC , the DC receiving end voltage level is high, and the DC is in control 1; when the thermal power unit power angle is greater than δ GC , the DC receiving end voltage level is low, and the DC is in control 2.

[0130] In the embodiment of the present application, the initial operation parameter and the first thermal power generating unit power angle are taken as the input of the preset thermal power generating unit power angle characteristic model, to obtain the first thermal power generating unit electromagnetic power and the second thermal power generating unit electromagnetic power.

[0131] It should be noted that under normal working conditions, the rectifier side operates in the CC control mode, at this time, the LCC-HVDC direct current side current I d satisfies:

[0132] (2)

[0133] wherein, is the normal working condition direct current side current.

[0134] The inverter side operates in the CEA control, and the inverter side arc extinguishing angle is a constant value , formula (2) and are substituted into formula (1) to obtain:

[0135] (3)

[0136] Let , then formula (3) can be rewritten as:

[0137] (4)

[0138] Formula (4) shows that the conventional direct current output characteristic under normal working conditions can be equivalent to a constant current source. The thermal power generating unit is equivalent to a voltage source, and the receiving end network is represented by an infinite power source. Under normal working conditions, the system equivalent circuit is shown in the following figure: Figure 20 , the mathematical model of the thermal power generating unit power angle characteristic curve can be obtained, and the derivation process is as follows:

[0139] The electromagnetic power expression of the thermal power generating unit output is:

[0140] (5)

[0141] wherein, the thermal power generating unit output current is the result of the joint action of the infinite power source, the thermal power generating unit and the direct current receiving end to the node G, which are respectively denoted as , , , and the expression is specifically:

[0142] (6)

[0143] wherein, is the infinite power source voltage, is the thermal power generating unit internal potential.

[0144] According to the linear network superposition principle, the mathematical expression of the output current of the thermal power unit is specifically:

[0145] (7)

[0146] Substituting formula (7) into formula (5) can obtain the mathematical expression of the electromagnetic power of the thermal power unit:

[0147] (8)

[0148] wherein, is the electromagnetic power of the thermal power unit, is the internal potential of the thermal power unit, is the voltage of the infinite power supply, is the power angle of the thermal power unit, is the phase angle of the conventional DC receiving end voltage.

[0149] It can be seen that the mathematical expression of the electromagnetic power of the thermal power unit is affected by the DC output current II and the phase angle of the terminal voltage , and therefore it is necessary to analyze the corresponding mathematical relationship between and the power angle of the thermal power unit , so as to clarify the influence of DC access on the power angle characteristic curve of the thermal power unit. As shown in FIG. 1, it can be seen that the conventional DC receiving end voltage Figure 20 is the result of the joint action of the voltage generated by the injection current of the S, G and W nodes at the W node, which are respectively denoted as , , , , and the expression thereof is shown in formula (9):

[0150] (9)

[0151] wherein, is the DC output current.

[0152] According to the linear network superposition principle, the sum of the three is shown in formula (10):

[0153] (10)

[0154] wherein, is the conventional DC receiving end voltage.

[0155] The DC adopts grid voltage orientation, and the power factor , the d-axis component I d of the output current is I I , and the q-axis component I q is 0. Taking the d-axis of the terminal voltage as the real axis reference direction, the dq decomposition is performed on formula (10), and U d , U qI d I q The DC receiving end voltage d-axis component and q-axis component expressions are available:

[0156] (11)

[0157] wherein, is the d-axis component of the terminal voltage, is the q-axis component of the terminal voltage.

[0158] By equation (11), U W can be converted to The corresponding relationship equation, equation (11) can be simplified by trigonometric function:

[0159] (12)

[0160] As can be seen from equation (4), under normal operating conditions, I I = 1.0pu, at this time the conventional DC receiving end voltage amplitude U W is:

[0161] (13)

[0162] According to the corresponding function relationship between U W and , equation (13) is substituted into equation (10), the mathematical expression between and can be established:

[0163] (14)

[0164] By Euler expansion of equation (14), the imaginary parts on both sides of the equation satisfy:

[0165] (15)

[0166] By trigonometric simplification of equation (15), the corresponding mathematical expression between and can be obtained:

[0167] (16)

[0168] wherein, the phase angle is equal to:

[0169] (17)

[0170] Thus, the mathematical model of the power angle characteristic curve of the thermal power generating unit under normal operating conditions can be determined as:

[0171] (18)

[0172] Under fault condition, rectifier side operates in VDCOL control mode, at this time LCC-HVDC DC side current I d Satisfies:

[0173] (19)

[0174] Where, VDCOL is the rectifier side DC voltage command value corresponding to VDCOL control, taking 0.9pu, is the U-I curve slope corresponding to VDCOL control. Inverter side operates in CEC control, inverter side trigger advance angle is a constant value , inverter side DC voltage U di Satisfies:

[0175] (20)

[0176] Let , formula (20) can be rewritten as:

[0177] (21)

[0178] Inverter side DC voltage U di and rectifier side DC voltage U dr Satisfies:

[0179] (22)

[0180] Combining (19)-(22), DC side current I d and DC receiving end voltage U W Satisfies:

[0181] (23)

[0182] From which the current I I and DC receiving end voltage U W The relationship is:

[0183] (24)

[0184] From formula (21) and formula (23), at this time the conventional DC output characteristic is a current source controlled by U W , the system equivalent circuit is shown in Figure 21 , the electromagnetic power expression of thermal power unit output is the same as formula (8), because I d is affected by U W , so the mathematical expression of thermal power unit electromagnetic power is affected by U W and δ WThe impact of U is therefore necessary to analyze. W and δ W With the power angle δ of the thermal power unit G The corresponding mathematical relationship between them clarifies the impact of DC input on the power angle characteristic curve of thermal power units. DC receiving-end voltage The expression is shown in equation (10). The expressions for the d-axis and q-axis components of the DC receiving-end voltage are similar to those in equation (11). U can be expressed using equation (11). W Transform into δ G The corresponding relationship can be simplified by using trigonometric functions to obtain equation (12). Combining equation (12) and equation (23), it can be seen that the amplitude of the conventional DC receiving-end voltage U at this time is... W for:

[0185] (25)

[0186] Solving equation (24) reveals that U W Regarding δ G The mathematical expression is:

[0187] (26)

[0188] δ W With δ G The mathematical expression between them, similar to formula (14), can be summarized as follows:

[0189] (27)

[0190] Therefore, the mathematical model for the power angle characteristic curve of a thermal power unit under fault conditions can be clearly defined as follows:

[0191] (28)

[0192] Step 204: Construct the instability range of the thermal power unit using the electromagnetic power of the first thermal power unit and the electromagnetic power of the second thermal power unit.

[0193] In this embodiment of the invention, the electromagnetic power P of the first thermal power unit is used. M1 The electromagnetic power P of the second thermal power unit M2 Constructing the instability range of thermal power units [P] M1 ,P M2 ].

[0194] Step 205: Based on the instability range of the thermal power unit, determine the power angle and critical cut-off power angle of the second thermal power unit corresponding to the AC / DC system according to the initial operating parameters;

[0195] Furthermore, step 205 includes the following sub-steps:

[0196] S21, judge whether the actual output of the thermal power generating unit with initial operation parameters is in the instability interval of the thermal power generating unit;

[0197] In the embodiment of the present application, the actual output of the thermal power generating unit with initial operation parameters is in the instability interval of the thermal power generating unit.

[0198] It should be noted that when the output of the thermal power generating unit is between P M1 and P M2 , the thermal power generating unit has no stable power angle at this time, and the thermal power generating unit will appear the swing divergence instability phenomenon; when the output of the thermal power generating unit is between P M1 and P M2 , the thermal power generating unit has no stable power angle at this time, and the thermal power generating unit will appear the swing divergence instability phenomenon. When the output of the thermal power generating unit is further increased, the output of the thermal power generating unit is higher than P M2 , the power angle acceleration area of the thermal power generating unit will be greater than the maximum deceleration area at this time, and the thermal power generating unit will appear the power angle aperiodic instability phenomenon.

[0199] S22, if the actual output of the thermal power generating unit is in the instability interval of the thermal power generating unit, adjust the output combination parameters, jump to execute the step of performing the steady-state power flow analysis on the topological structure according to the preset output combination parameters to obtain the initial operation parameters corresponding to the AC / DC system;

[0200] In the embodiment of the present application, if the actual output of the thermal power generating unit is in the instability interval of the thermal power generating unit, the thermal power generating unit has no stable power angle, the output combination parameters are adjusted, and the step 201 is executed.

[0201] S23, if the actual output of the thermal power generating unit is not in the instability interval of the thermal power generating unit, the segmented calculation method is used to perform the fault removal analysis on the initial operation parameters to obtain the second power angle of the thermal power generating unit corresponding to the AC / DC system.

[0202] In the embodiment of the present application, if the actual output of the thermal power generating unit is not in the instability interval of the thermal power generating unit, the thermal power generating unit will appear the power angle aperiodic instability phenomenon, the segmented calculation method is used to perform the fault removal analysis on the initial operation parameters to obtain the second power angle of the thermal power generating unit corresponding to the AC / DC system.

[0203] It should be noted that the step of performing the fault removal analysis on the initial operation parameters by using the segmented calculation method specifically comprises: inputting the initial operation parameters into a preset segmented calculation function to obtain the second power angle of the thermal power generating unit corresponding to the AC / DC system.

[0204] The segmented calculation function specifically comprises:

[0205]

[0206] wherein, is the second power angle of the thermal power generating unit, is the actual output of the thermal power generating unit, is a segmented coefficient, is an initial power angle of the thermal power unit, is a rated angular velocity of the system, and is 18000° / s, is an inertia time constant of the thermal power unit, is a solution interval of the segmented calculation method, and is 0.05s.

[0207] S24, inputting the second thermal power unit power angle and the initial operation parameter into a preset critical removal power angle function to obtain a critical removal power angle corresponding to the AC / DC system.

[0208] In the embodiment of the present application, the second thermal power unit power angle and the initial operation parameter are inputted as inputs of the preset critical removal power angle function to obtain the critical removal power angle corresponding to the AC / DC system.

[0209] It should be noted that the critical removal power angle function is specifically as follows:

[0210]

[0211] Step 206, performing non-periodic instability analysis by using the second thermal power unit power angle, the critical removal power angle and the initial operation parameter to obtain a power angle stability margin evaluation value corresponding to the AC / DC system.

[0212] Further, the step 206 includes the following sub-steps:

[0213] S31, performing power angle characteristic analysis by using the second thermal power unit power angle, the critical removal power angle and the initial operation parameter to obtain an acceleration area and a maximum deceleration area corresponding to the AC / DC system;

[0214] Further, the S31 includes the following sub-steps:

[0215] S311, constructing a maximum deceleration interval by using the critical removal power angle and the second thermal power unit power angle;

[0216] S312, performing differential operation on a difference between the initial operation parameter thermal power unit output electromagnetic power and the actual thermal power unit output based on the maximum deceleration interval to obtain the maximum deceleration area corresponding to the AC / DC system;

[0217] In the embodiment of the present application, the critical removal power angle, the second thermal power unit power angle, the initial operation parameter thermal power unit output electromagnetic power and the actual thermal power unit output are inputted into a preset maximum deceleration area function to obtain the maximum deceleration area corresponding to the AC / DC system.

[0218] It should be noted that the maximum deceleration area function is specifically as follows:

[0219]

[0220] wherein, is the maximum deceleration area, is the output electromagnetic power of the thermal power unit, is the actual output of the thermal power unit, is the power angle of the thermal power unit, δ GF is the second power angle of the thermal power unit, δ Gcr is the critical cut-off power angle.

[0221] S313, difference processing is performed on the second power angle of the thermal power unit and the initial power angle of the thermal power unit of the initial operation parameter to obtain a first difference value;

[0222] S314, multiplication processing is performed on the actual output of the thermal power unit and the first difference value to obtain a power angle acceleration area corresponding to the AC / DC system.

[0223] In the embodiment of the present application, the second power angle of the thermal power unit, the initial power angle of the thermal power unit and the actual output of the thermal power unit are input into a preset power angle acceleration area function to obtain the power angle acceleration area corresponding to the AC / DC system.

[0224] It should be noted that the power angle acceleration area function is specifically:

[0225]

[0226] wherein, is the power angle acceleration area.

[0227] S32, it is judged whether the acceleration area is greater than or equal to the maximum deceleration area;

[0228] S33, if the acceleration area is greater than or equal to the maximum deceleration area, the output combination parameter is adjusted, and the step of performing steady-state power flow analysis on the topology according to the preset output combination parameter to obtain the initial operation parameter corresponding to the AC / DC system is executed;

[0229] In the embodiment of the present application, it is judged whether the acceleration area is greater than or equal to the maximum deceleration area, and if the acceleration area is greater than or equal to the maximum deceleration area, it indicates that the power angle of the thermal power unit is non-periodic instability, the output combination parameter is adjusted, and the step 201 is executed.

[0230] S34, if the acceleration area is less than the maximum deceleration area, the critical cut-off power angle is determined as the power angle stability margin evaluation value corresponding to the AC / DC system.

[0231] In the embodiment of the present application, if the acceleration area is less than the maximum deceleration area, it indicates that the power angle of the thermal power unit is not non-periodic instability, and the critical cut-off power angle is determined as the power angle stability margin evaluation value corresponding to the AC / DC system.

[0232] It should be noted that the smaller the stability margin evaluation value is, the more stable the AC-DC system is.

[0233] It is worth mentioning that, as shown in the system Figure 7 , the AC-DC system power angle stability analysis method of steps 201-206 is combined to Figure 7 evaluate the power angle stability margin of the corresponding system, and the results are shown in Table 5, and the corresponding simulation results are shown in Figure 23-26 .

[0234]

[0235] Table 5

[0236] In the embodiment of the present application, by obtaining the initial operating parameters of the AC-DC system, and based on this, the power angle stability margin of the system is evaluated, the instability interval of the thermal power unit is obtained, and then the power angle stability margin of the AC-DC system is evaluated according to the instability interval of the thermal power unit and the initial operating parameters, thereby realizing accurate evaluation of the DC control power angle stability margin, and solving the technical problem that the existing research does not fully consider the influence of DC control mode switching when analyzing the power angle stability of the AC-DC system, resulting in low accuracy of the stability margin evaluation of the AC-DC system. Compared with the traditional power angle stability margin evaluation method, the power angle stability margin of the AC-DC system is evaluated according to the instability interval of the thermal power unit and the initial operating parameters, the power angle characteristics of the thermal power unit under different control strategies are considered, the influence of DC control switching on the power angle stability of the thermal power unit is determined, and the AC-DC system is accurately evaluated, thereby improving the reliability of the AC-DC system.

[0237] Please refer to Figure 27 , Figure 27 for the structure block diagram of an AC-DC system power angle stability analysis system provided in Embodiment Three of the present application.

[0238] The AC-DC system power angle stability analysis system provided by the present application comprises:

[0239] The acquisition module 301 is configured to obtain the topological structure of the AC-DC system, and perform steady-state power flow analysis on the topological structure according to the preset output combination parameters, to obtain the initial operating parameters of the AC-DC system.

[0240] The stability evaluation module 302 is configured to evaluate the power angle stability of the AC-DC system based on the initial operating parameters, to obtain the instability interval of the thermal power unit.

[0241] The analysis module 303 is configured to determine the second power angle of the thermal power unit and the critical cut-off power angle of the AC-DC system according to the initial operating parameters based on the instability interval of the thermal power unit.

[0242] The margin evaluation module 304 is configured to perform non-periodic instability analysis on the second power angle of the thermal power generator, the critical cut-off power angle and the initial operation parameter, to obtain the power angle stability margin evaluation value corresponding to the AC / DC system.

[0243] Further, the collection module 301 comprises:

[0244] The first construction submodule is configured to construct a simulation model of the thermal power generator near the DC infeed landing point by using the topological structure.

[0245] The loading submodule is configured to input the preset output combination parameter into the simulation model of the thermal power generator near the DC infeed landing point, to obtain a target AC / DC system simulation model.

[0246] The power flow analysis submodule is configured to perform system power flow analysis on the target AC / DC system simulation model, to obtain the initial operation parameter corresponding to the AC / DC system.

[0247] Further, the stability evaluation module 302 comprises:

[0248] The first analysis submodule is configured to input the initial operation parameter and the characteristic parameter of the AC / DC system into a preset first power angle function, to obtain the first power angle of the thermal power generator.

[0249] The second analysis submodule is configured to input the initial operation parameter and the first power angle of the thermal power generator into a preset thermal power generator power angle characteristic model, to obtain the first electromagnetic power of the thermal power generator and the second electromagnetic power of the thermal power generator.

[0250] The second construction submodule is configured to construct a thermal power generator instability interval by using the first electromagnetic power of the thermal power generator and the second electromagnetic power of the thermal power generator.

[0251] Further, the margin evaluation module 304 comprises:

[0252] The third analysis submodule is configured to determine whether the actual output of the thermal power generator at the initial operation parameter is in the thermal power generator instability interval.

[0253] If the actual output of the thermal power generator is in the thermal power generator instability interval, the output combination parameter is adjusted, and the step of performing steady-state power flow analysis on the topological structure according to the preset output combination parameter is executed to obtain the initial operation parameter corresponding to the AC / DC system.

[0254] If the actual output of the thermal power generator is not in the thermal power generator instability interval, the initial operation parameter is analyzed by using the piecewise calculation method to obtain the second power angle of the thermal power generator corresponding to the AC / DC system.

[0255] The fourth analysis submodule is configured to input the second power angle of the thermal power generator and the initial operation parameter into a preset critical cut-off power angle function, to obtain the critical cut-off power angle corresponding to the AC / DC system.

[0256] Further, the margin evaluation module 304 comprises:

[0257] The power angle characteristic analysis submodule is configured to perform power angle characteristic analysis by using the second thermal power generating unit power angle, the critical cut-off power angle and the initial operation parameter to obtain the acceleration area and the maximum deceleration area corresponding to the AC / DC system.

[0258] The fifth analysis submodule is configured to determine whether the acceleration area is greater than or equal to the maximum deceleration area.

[0259] If the acceleration area is greater than or equal to the maximum deceleration area, the output combination parameter is adjusted, and the step of performing steady-state power flow analysis on the topology according to the preset output combination parameter to obtain the initial operation parameter corresponding to the AC / DC system is executed.

[0260] If the acceleration area is less than the maximum deceleration area, the critical cut-off power angle is determined as the power angle stability margin evaluation value corresponding to the AC / DC system.

[0261] Further, the power angle characteristic analysis submodule comprises:

[0262] The first analysis unit is configured to construct the maximum deceleration interval by using the critical cut-off power angle and the second thermal power generating unit power angle.

[0263] The second analysis unit is configured to perform differential operation on the difference between the thermal power generating unit output electromagnetic power and the actual output of the thermal power generating unit of the initial operation parameter based on the maximum deceleration interval to obtain the maximum deceleration area corresponding to the AC / DC system.

[0264] The third analysis unit is configured to perform difference processing on the second thermal power generating unit power angle and the initial power angle of the thermal power generating unit of the initial operation parameter to obtain a first difference value.

[0265] The fourth analysis unit is configured to perform multiplication processing on the actual output of the thermal power generating unit and the first difference value to obtain the power angle acceleration area corresponding to the AC / DC system.

[0266] Please refer to Figure 28 , Figure 28 The structure block diagram of the electronic device provided in Embodiment Four of the present application.

[0267] The electronic device of the embodiment of the present application comprises a memory 401 and a processor 402, and the memory 402 stores a computer program; when the computer program is executed by the processor 402, the processor 402 executes the AC / DC system power angle stability analysis method of any one of the above embodiments.

[0268] The memory 401 can be an electronic memory such as a flash memory, an EEPROM (Electrically Erasable Programmable Read-Only Memory), an EPROM, a hard disk or a ROM. The memory 401 has a storage space 403 for program codes 413 for performing any of the method steps in the above-described methods. For example, the storage space 403 for program codes can comprise individual program codes 413 for implementing the various steps in the above-described methods, respectively. These program codes can be read from or written to one or more computer program products. These computer program products include program code carriers such as hard disks, compact disks (CDs), memory cards or floppy disks. The program codes can be compressed, for example, in a suitable form. These codes, when run by a computing processing device, cause the computing processing device to perform the individual steps in the above-described methods.

[0269] Embodiment five of the present application also provides a computer readable storage medium, having stored thereon a computer program, which, when executed by a processor, implements the AC / DC system power angle stability analysis method according to any of the above embodiments.

[0270] Embodiment six of the present application also provides a computer program product, which comprises a computer program stored on a non-transitory computer readable storage medium, and the computer program comprises program instructions, wherein when the program instructions are executed by a computer, the computer executes the AC / DC system power angle stability analysis method according to any of the above embodiments.

[0271] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described system, device and unit can refer to the corresponding processes in the foregoing method embodiments, which will not be repeated here.

[0272] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other ways. For example, the above-described device embodiments are only schematic, for example, the division of units is only a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the shown or discussed units can be indirect coupling or communication connection through some interfaces, devices or units, and can be electrical, mechanical or other forms.

[0273] The units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, i.e., may be located in one place, or may be distributed to multiple network units. Part or all of the units may be selected according to actual needs to achieve the purpose of the embodiment.

[0274] In addition, each functional unit in each embodiment of the application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0275] If the integrated unit is realized in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the application, the essential part or the whole or part of the prior art, or the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method of each embodiment of the application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various program code storage media.

[0276] The above embodiments are only used to illustrate the technical solutions of the application, but not to limit them; although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the application.

Claims

1. An AC / DC system power angle stability analysis method, characterized by, The method comprises the following steps: obtaining the topology of an AC-DC system, and performing steady-state power flow analysis on the topology according to preset output combination parameters to obtain initial operating parameters corresponding to the AC-DC system; inputting the initial operating parameters and characteristic parameters of the AC-DC system into a preset first power angle function to obtain a first thermal power unit power angle; inputting the initial operating parameters and the first thermal power unit power angle into a preset thermal power unit power angle characteristic model to obtain a first thermal power unit electromagnetic power and a second thermal power unit electromagnetic power; constructing a thermal power unit instability interval using the first thermal power unit electromagnetic power and the second thermal power unit electromagnetic power; determining whether the actual output of the thermal power unit in the initial operating parameters is in the thermal power unit instability interval; if the actual output of the thermal power unit is in the thermal power unit instability interval, adjusting the output combination parameters and jumping to perform the step of performing steady-state power flow analysis on the topology according to the preset output combination parameters to obtain the initial operating parameters corresponding to the AC-DC system; if the actual output of the thermal power unit is not in the thermal power unit instability interval, performing fault removal analysis on the initial operating parameters using a piecewise calculation method to obtain a second thermal power unit power angle corresponding to the AC-DC system; inputting the second thermal power unit power angle and the initial operating parameters into a preset critical removal power angle function to obtain a critical removal power angle corresponding to the AC-DC system; performing power angle characteristic analysis using the second thermal power unit power angle, the critical removal power angle, and the initial operating parameters to obtain an acceleration area and a maximum deceleration area corresponding to the AC-DC system; determining whether the acceleration area is greater than or equal to the maximum deceleration area; if the acceleration area is greater than or equal to the maximum deceleration area, adjusting the output combination parameters and jumping to perform the step of performing steady-state power flow analysis on the topology according to the preset output combination parameters to obtain the initial operating parameters corresponding to the AC-DC system; if the acceleration area is less than the maximum deceleration area, determining the critical removal power angle as a power angle stability margin evaluation value corresponding to the AC-DC system.

2. The AC / DC system power angle stability analysis method according to claim 1, characterized by, The step of performing steady-state power flow analysis on the topology according to the preset output combination parameters to obtain the initial operating parameters corresponding to the AC-DC system comprises the following steps: constructing a DC feeder drop point near thermal power unit simulation model using the topology; inputting the preset output combination parameters into the DC feeder drop point near thermal power unit simulation model to obtain a target AC-DC system simulation model; performing system power flow analysis on the target AC-DC system simulation model to obtain the initial operating parameters corresponding to the AC-DC system.

3. The AC / DC system power angle stability analysis method according to claim 1, wherein The step of performing power angle characteristic analysis using the second thermal power unit power angle, the critical removal power angle, and the initial operating parameters to obtain the acceleration area and the maximum deceleration area corresponding to the AC-DC system comprises the following steps: constructing a maximum deceleration interval using the critical removal power angle and the second thermal power unit power angle; Differential operation is performed on a difference between the initial operation parameter of the thermal power generating unit output electromagnetic power and the actual output of the thermal power generating unit based on the maximum deceleration interval, to obtain a maximum deceleration area corresponding to the AC / DC system; A second thermal power generating unit power angle is obtained by subtracting the initial power angle of the initial operation parameter of the thermal power generating unit from the initial power angle of the initial operation parameter of the thermal power generating unit; The actual output of the thermal power generating unit is multiplied by the first difference value to obtain a power angle acceleration area corresponding to the AC / DC system.

4. An AC / DC system power angle stability analysis system for implementing the AC / DC system power angle stability analysis method according to any one of claims 1 to 3, characterized by Comprise: The acquisition module is used for acquiring the topology structure of the AC / DC system, and performing steady-state power flow analysis on the topology structure according to the preset output combination parameter, to obtain the initial operation parameter corresponding to the AC / DC system; The stability evaluation module is used for performing power angle stability evaluation on the AC / DC system based on the initial operation parameter, to obtain a thermal power generating unit instability interval; The analysis module is used for determining a second thermal power generating unit power angle and a critical cut-off power angle corresponding to the AC / DC system according to the initial operation parameter based on the thermal power generating unit instability interval; The margin evaluation module is used for performing non-periodic instability analysis by using the second thermal power generating unit power angle, the critical cut-off power angle and the initial operation parameter, to obtain a power angle stability margin evaluation value corresponding to the AC / DC system.

5. An electronic device, comprising: The computer program is executed by the processor, so that the processor executes the steps of the AC / DC system power angle stability analysis method according to any one of claims 1-3.

6. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed to realize the AC / DC system power angle stability analysis method according to any one of claims 1-3.

7. A computer program product, characterised in that, The computer program product comprises a computer program stored on a non-transitory computer readable storage medium, and the computer program comprises program instructions, wherein when the program instructions are executed by a computer, the computer executes the AC / DC system power angle stability analysis method according to any one of claims 1-3.

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