Stability determination method, apparatus, device, storage medium, and program product

Abstract

The application relates to a stability determination method and device, computer equipment, a storage medium and a computer program product. The method comprises the following steps: calculating a steady-state working point of a high-voltage direct-current power transmission system according to system parameters in the high-voltage direct-current power transmission system, the high-voltage direct-current power transmission system comprising a sending-end system and a receiving-end system, the steady-state working point comprising a first steady-state working point of positive and negative poles of the sending-end system and a second steady-state working point of positive and negative poles of the receiving-end system; calculating a first equivalent impedance according to the steady-state working point, the first equivalent impedance being equivalent impedance of positive and negative poles of a direct-current side of the sending-end system; calculating positive and negative pole AC impedances of a d-axis and positive and negative pole AC impedances of a q-axis in the high-voltage direct-current power transmission system according to the first equivalent impedance, and performing stability analysis and processing on the high-voltage direct-current power transmission system according to the positive and negative pole AC impedances of the d-axis and the positive and negative pole AC impedances of the q-axis. The method can determine the stability of a double-ended double-pole high-voltage direct-current power transmission system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-voltage direct current transmission systems, and in particular to a stability determination method, device, equipment, storage medium and program product. BACKGROUND

[0002] The imbalance between China's economic development and energy distribution promotes the development of the West-to-East and South-to-North power transmission projects in China, and the high-voltage direct current transmission technology has been widely applied due to its advantages of large transmission power and small loss. With the continuous increase of social power load in China, the transmission capacity of the line-commutated converter based high-voltage direct current (LCC-HVDC) transmission technology is increasing, and the system is facing more and more serious oscillation risks. Therefore, it is of great significance to analyze the stability of LCC-HVDC.

[0003] In related technologies, LCC-HVDC is generally modeled based on the average value method, and by analyzing the stability of the LCC-HVDC model, the purpose of analyzing the stability of LCC-HVDC in actual projects can be achieved.

[0004] However, the current research is limited to the stability analysis of single-ended LCC-HVDC or double-ended single-pole LCC-HVDC, and there is no in-depth method for stability analysis of double-ended bipolar LCC-HVDC. Therefore, there is an urgent need for a method for stability analysis of double-ended bipolar LCC-HVDC in actual projects. SUMMARY

[0005] Therefore, it is necessary to provide a stability determination method, device, equipment, storage medium and program product to solve the above technical problems.

[0006] In a first aspect, the present application provides a stability determination method. The method comprises:

[0007] According to the system parameters in the high-voltage direct current transmission system, the steady-state operating point of the high-voltage direct current transmission system is calculated, the high-voltage direct current transmission system comprises a sending end system and a receiving end system, and the steady-state operating point comprises a first steady-state operating point of the positive and negative poles of the sending end system and a second steady-state operating point of the positive and negative poles of the receiving end system; according to the steady-state operating point, a first equivalent impedance is calculated, the first equivalent impedance is the equivalent impedance of the positive and negative poles of the sending end system on the direct current side; according to the first equivalent impedance, the positive and negative pole AC impedances of the d-axis and the positive and negative pole AC impedances of the q-axis in the high-voltage direct current transmission system are calculated, and the stability of the high-voltage direct current transmission system is analyzed and processed according to the positive and negative pole AC impedances of the d-axis and the positive and negative pole AC impedances of the q-axis.

[0008] In one of the embodiments, the first equivalent impedance is calculated according to the steady state operating point, including:

[0009] The second equivalent impedance is calculated according to the steady state operating point, the second equivalent impedance being equivalent impedance of positive and negative poles of DC side of the receiving end system; the first equivalent impedance is calculated according to the second equivalent impedance.

[0010] In one of the embodiments, the second equivalent impedance is calculated according to the steady state operating point, including:

[0011] Small signal processing is performed near the steady state operating point to obtain a first variation parameter; the second equivalent impedance is calculated according to the first variation parameter.

[0012] In one of the embodiments, the second equivalent impedance is calculated according to the first variation parameter, including:

[0013] The first equation set is obtained by combining the positive and negative pole converter equation corresponding to the receiving end system, the positive and negative pole control system equation corresponding to the receiving end system and the AC power grid equation corresponding to the receiving end system; the receiving end system DC current variation in the first variation parameter is set to 1, and the first variation parameter is substituted into the first equation set to obtain a second variation parameter; the second equivalent impedance is calculated according to the second variation parameter.

[0014] In one of the embodiments, the first equivalent impedance is calculated according to the second equivalent impedance, including:

[0015] The DC line connecting the receiving end system and the sending end system is subjected to π-type equivalent processing to obtain an equivalent impedance calculation formula; the second equivalent impedance is substituted into the equivalent impedance calculation formula to obtain the first equivalent impedance.

[0016] In one of the embodiments, the positive and negative pole AC impedance of d-axis and the positive and negative pole AC impedance of q-axis in the HVDC transmission system are calculated according to the first equivalent impedance, including:

[0017] The second equation set is obtained by combining the positive and negative pole converter equation corresponding to the sending end system, the positive and negative pole control system equation corresponding to the sending end system and the DC power grid equation corresponding to the sending end system; the first equivalent impedance and the first variation parameter are substituted into the second equation set to obtain the positive and negative pole AC impedance of d-axis and the positive and negative pole AC impedance of q-axis.

[0018] In one of the embodiments, the first equivalent impedance and the first variation parameter are substituted into the second equation set to obtain the positive and negative pole AC impedance of d-axis and the positive and negative pole AC impedance of q-axis, including:

[0019] The first equivalent impedance and the first variation parameter are substituted into the second equation set, and the variation of the d-axis voltage of the AC bus of the sending end system is 1 and the variation of the q-axis voltage of the AC bus of the sending end system is 0, to obtain the positive and negative pole AC impedance of the d-axis; the first equivalent impedance and the first variation parameter are substituted into the second equation set, and the variation of the d-axis voltage of the AC bus of the sending end system is 0 and the variation of the q-axis voltage of the AC bus of the sending end system is 1, to obtain the positive and negative pole AC impedance of the q-axis.

[0020] In a second aspect, the present application further provides a stability determination device. The device comprises:

[0021] A first calculation module is configured to calculate a steady state operating point of a high voltage direct current (HVDC) transmission system according to system parameters in the HVDC transmission system, the HVDC transmission system comprising a sending end system and a receiving end system;

[0022] A second calculation module is configured to calculate a first equivalent impedance according to the steady state operating point, the first equivalent impedance being a bipolar equivalent impedance of a DC side of the sending end system;

[0023] A third calculation module is configured to calculate bipolar AC impedances of a d-axis and a q-axis in the HVDC transmission system according to the first equivalent impedance, and to perform stability analysis and processing on the HVDC transmission system according to the bipolar AC impedances of the d-axis and the q-axis.

[0024] In one embodiment, the second calculation module comprises:

[0025] A first calculation unit is configured to calculate a second equivalent impedance according to the steady state operating point, the second equivalent impedance being a positive and negative pole equivalent impedance of a DC side of the receiving end system;

[0026] A second calculation unit is configured to calculate the first equivalent impedance according to the second equivalent impedance.

[0027] In one embodiment, the first calculation unit is specifically configured to perform small signal processing around the steady state operating point to obtain a first variation parameter; and calculate the second equivalent impedance according to the first variation parameter.

[0028] In one embodiment, the first calculation unit is specifically configured to obtain a first equation set by simultaneously solving a positive and negative pole converter equation corresponding to the receiving end system, a positive and negative pole control system equation corresponding to the receiving end system, and an AC grid equation corresponding to the receiving end system; substitute a receiving end system DC current variation in the first variation parameter into the first equation set to obtain a second variation parameter; and calculate the second equivalent impedance according to the second variation parameter.

[0029] In one of the embodiments, the second calculation unit is specifically configured to perform π-type equivalent processing on the DC line connecting the receiving end system and the sending end system to obtain an equivalent impedance calculation formula; and the second equivalent impedance is substituted into the equivalent impedance calculation formula to obtain the first equivalent impedance.

[0030] In one of the embodiments, the third calculation module comprises:

[0031] The third calculation unit is configured to obtain a second equation group by simultaneously solving the positive and negative converter equations corresponding to the sending end system, the positive and negative control system equations corresponding to the sending end system, and the DC grid equations corresponding to the sending end system.

[0032] The fourth calculation unit is configured to substitute the first equivalent impedance and the first change parameter into the second equation group to obtain the positive and negative AC impedance of the d-axis and the positive and negative AC impedance of the q-axis.

[0033] In one of the embodiments, the fourth calculation unit is specifically configured to substitute the first equivalent impedance and the first change parameter into the second equation group, and set the d-axis voltage change of the AC bus of the sending end system to 1 and the q-axis voltage change of the AC bus of the sending end system to 0 to obtain the positive and negative AC impedance of the d-axis; and substitute the first equivalent impedance and the first change parameter into the second equation group, and set the d-axis voltage change of the AC bus of the sending end system to 0 and the q-axis voltage change of the AC bus of the sending end system to 1 to obtain the positive and negative AC impedance of the q-axis.

[0034] In a third aspect, an embodiment of the present application provides a computer device having a computer program stored thereon, and the computer program is executed by a processor to implement the steps of any one of the first aspect.

[0035] In a fourth aspect, an embodiment of the present application provides a computer readable storage medium having a computer program stored thereon, and the computer program is executed by a processor to implement the steps of any one of the first aspect.

[0036] In a fifth aspect, an embodiment of the present application provides a computer program product having a computer program stored thereon, and the computer program is executed by a processor to implement the steps of any one of the first aspect.

[0037] The stability determination method, device, equipment, storage medium and program product determine the stability of the high-voltage direct current power transmission system by calculating the steady state working point of the high-voltage direct current power transmission system according to the system parameters of the high-voltage direct current power transmission system, the high-voltage direct current power transmission system including a sending end system and a receiving end system, the steady state working point including a first steady state working point of the positive and negative poles of the sending end system and a second steady state working point of the positive and negative poles of the receiving end system, calculating a first equivalent impedance according to the steady state working point, the first equivalent impedance being the equivalent impedance of the positive and negative poles of the direct current side of the sending end system, calculating the positive and negative pole AC impedances of the d-axis and the positive and negative pole AC impedances of the q-axis of the high-voltage direct current power transmission system according to the first equivalent impedance, and performing stability analysis and processing on the high-voltage direct current power transmission system according to the positive and negative pole AC impedances of the d-axis and the positive and negative pole AC impedances of the q-axis. Through the embodiment, the stability of the double-terminal double-pole high-voltage direct current power transmission system can be determined. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 A flowchart of a stability determination method provided by an embodiment of the present application;

[0039] Figure 2 A flowchart of a method for calculating a first equivalent impedance provided by an embodiment of the present application;

[0040] Figure 3 A flowchart of a method for calculating a second equivalent impedance provided by an embodiment of the present application;

[0041] Figure 4 A flowchart of a method for calculating a second equivalent impedance provided by another embodiment of the present application;

[0042] Figure 5 A flowchart of a method for calculating a first equivalent impedance provided by another embodiment of the present application;

[0043] Figure 6 A Π-type equivalent circuit diagram provided by an embodiment of the present application;

[0044] Figure 7 A flowchart of a method for calculating the positive and negative pole AC impedances of the d-axis and the positive and negative pole AC impedances of the q-axis provided by an embodiment of the present application;

[0045] Figure 8 A flowchart of a stability determination method provided by another embodiment of the present application;

[0046] Figure 9 A structural block diagram of a stability determination device in an embodiment;

[0047] Figure 10 An internal structural diagram of a computer device as a server in an embodiment;

[0048] Figure 11Fig. 1 is a schematic diagram of an internal structure of a computer device as a terminal in one embodiment. DETAILED DESCRIPTION

[0049] For the purpose, technical solutions and advantages of the present application to be more clearly and obviously, the present application is further described in detail below in combination with the drawings and embodiments.

[0050] With the continuous increase of social power load in China, the transmission capacity of high-voltage direct current power transmission system is increasing, and the risk of oscillation faced by the system is becoming more and more serious. Therefore, it has become an important problem to accurately analyze the stability of the high-voltage direct current power transmission system.

[0051] In the related art, the high-voltage direct current power transmission system is modeled based on the average value method, and by analyzing the stability of the high-voltage direct current power transmission system model, the purpose of analyzing the stability of the high-voltage direct current power transmission system in actual engineering can be achieved. However, the current research is limited to modeling of single-ended high-voltage direct current power transmission system or double-ended single-pole high-voltage direct current power transmission system, and has not deeply modeled the double-ended bipolar high-voltage direct current power transmission system.

[0052] The stability determination method provided by the embodiments of the present application can be used for stability analysis of the double-ended bipolar high-voltage direct current power transmission system in actual engineering, and makes up for the deficiency that the current research has not deeply analyzed the stability of the double-ended bipolar high-voltage direct current power transmission system.

[0053] The stability determination method provided by the embodiments of the present application can be used for stability analysis of the double-ended bipolar high-voltage direct current power transmission system in actual engineering, and makes up for the deficiency that the current research has not deeply analyzed the stability of the double-ended bipolar high-voltage direct current power transmission system.

[0054] In one embodiment, the stability determination method provided by the embodiments of the present application comprises the following steps as shown in Figure 1

[0055] Step 101, calculating a steady-state operating point of the high-voltage direct current power transmission system according to system parameters in the high-voltage direct current power transmission system.

[0056] The high-voltage direct current power transmission system can use high-voltage direct current power transmission technology based on grid commutated converters for power transmission, which includes a sending-end system and a receiving-end system.

[0057] ​The system parameters are obtained according to an actual engineering model, and include: an AC line parameter of a sending-end system, an AC filter parameter of the sending-end system, a bus voltage level of the sending-end system, a transformer parameter of the sending-end system, a two-pole control mode of the sending-end system, a controlled quantity reference value of the sending-end system, a phase-locked loop transfer function of the sending-end system, a controller transfer function of the sending-end system, a DC line parameter, an AC line parameter of a receiving-end system, a converter filter parameter of the receiving-end system, a bus voltage level of the receiving-end system, a transformer parameter of the receiving-end system, a two-pole control mode of the receiving-end system, a controlled quantity reference value of the receiving-end system, a phase-locked loop transfer function of the receiving-end system, and a controller transfer function of the receiving-end system. The steady-state working point of the double-terminal double-pole high-voltage DC power transmission system is calculated based on the average method according to the obtained system parameters.

[0058] The steady-state working point includes a first steady-state working point of positive and negative poles of the sending-end system and a second steady-state working point of positive and negative poles of the receiving-end system. When the double-terminal double-pole high-voltage DC power transmission system is symmetrically operated by the positive and negative pole converters, the steady-state working points of the positive and negative poles are the same.

[0059] The first steady-state working point includes a 12-pulse converter steady-state working point of the positive pole of the sending-end system and a 12-pulse converter steady-state working point of the negative pole of the sending-end system.

[0060] The second steady-state working point includes a 12-pulse converter steady-state working point of the positive pole of the receiving-end system and a 12-pulse converter steady-state working point of the negative pole of the receiving-end system.

[0061] Step 102, a first equivalent impedance is calculated according to the steady-state working point.

[0062] The first equivalent impedance is an equivalent impedance of positive and negative poles of a DC side of the sending-end system.

[0063] Step 103, positive and negative pole AC impedances of a d-axis and positive and negative pole AC impedances of a q-axis in the high-voltage DC power transmission system are calculated according to the first equivalent impedance, and stability analysis and processing of the high-voltage DC power transmission system are performed according to the positive and negative pole AC impedances of the d-axis and the positive and negative pole AC impedances of the q-axis.

[0064] Small signal processing is performed near the steady-state working point to obtain a first variation parameter, and then the second equivalent impedance is calculated according to the first variation parameter. The equivalent impedance calculation formula is obtained by performing π-type equivalent processing on a DC line connecting the receiving-end system and the sending-end system, and the first equivalent impedance is obtained by substituting the second equivalent impedance into the equivalent impedance calculation formula.

[0065] The stability determination method calculates a steady state working point of the high voltage direct current power transmission system according to system parameters in the high voltage direct current power transmission system, the high voltage direct current power transmission system comprising a sending end system and a receiving end system, the steady state working point comprising a first steady state working point of positive and negative poles of the sending end system and a second steady state working point of positive and negative poles of the receiving end system, then calculates a first equivalent impedance according to the steady state working point, the first equivalent impedance being equivalent impedance of positive and negative poles of a direct current side of the sending end system, then calculates positive and negative pole alternating current impedance of a d-axis and positive and negative pole alternating current impedance of a q-axis in the high voltage direct current power transmission system according to the first equivalent impedance, and performs stability analysis and processing on the high voltage direct current power transmission system according to the positive and negative pole alternating current impedance of the d-axis and the positive and negative pole alternating current impedance of the q-axis. Through the embodiment, the stability of the double-ended bipolar high voltage direct current power transmission system can be determined.

[0066] In the following, the embodiment of the application provides an optional way of calculating the steady state working point, wherein the way comprises the following steps:

[0067] In the optional embodiment of the application, the computer device can calculate the steady state working point according to the following equation:

[0068] Steady state working point of the positive pole 12 pulse current converter of the sending end system:

[0069]

[0070] wherein, u dc_r1 represents direct current side voltage of the positive pole converter to ground, v d_r and v q_r represent the size of the bus voltage of the sending end system under the dq axis, a r1 represents the trigger angle of the positive pole converter of the sending end system, d r1 represents the turn-off angle of the positive pole converter of the sending end system, i dc_r1 represents the direct current side current of the positive pole converter of the sending end system, the positive direction is defined as the direction of flowing out of the converter, X c_r represents the size of the leakage reactance of the alternating current transformer of the sending end system, i d_r1 / i q_r1 is the size of the bus current of the positive pole converter of the sending end system under the dq axis, and the positive direction is defined as the direction of flowing from the bus into the converter.

[0071] Steady state working point of the negative pole 12 pulse current converter of the sending end system:

[0072]

[0073] wherein, u dc_r2 represents direct current side voltage of the negative pole converter of the sending end system to ground, a r2 represents the trigger angle of the negative pole converter of the sending end system, d r2 represents the turn-off angle of the negative pole converter of the sending end system, ii dc_r2 represents the DC side current of the sending system positive converter, whose positive direction is defined as the direction flowing into the converter. d_r2 i q_r2 is the size of the bus current of the sending system positive converter in the dq axis, whose positive direction is defined as the direction flowing from the bus into the converter.

[0074] Receiving system positive 12-pulse converter steady-state operating point:

[0075]

[0076] wherein u dc_i1 represents the DC side voltage of the receiving system positive converter to ground, v d_i and v q_i represents the size of the bus voltage of the receiving system in the dq axis, a i1 represents the triggering angle of the receiving system positive converter, d i1 represents the turn-off angle of the receiving system positive converter, i dc_i1 represents the DC side current of the receiving system positive converter, whose positive direction is defined as the direction flowing into the converter, X c_i represents the size of the receiving system AC transformer leakage reactance, i d_i1 i q_i1 is the size of the bus current of the receiving system positive converter in the dq axis, whose positive direction is defined as the direction flowing from the bus into the converter.

[0077] Receiving system negative 12-pulse converter steady-state operating point:

[0078]

[0079] wherein u dc_i2 represents the DC side voltage of the receiving system negative converter to ground, a i2 represents the triggering angle of the receiving system negative converter, d i2 represents the turn-off angle of the receiving system negative converter, i dc_i2 represents the DC side current of the receiving system negative converter, whose positive direction is defined as the direction flowing out of the converter, i d_i2 i q_i2 is the size of the bus current of the receiving system negative converter in the dq axis, whose positive direction is defined as the direction flowing from the bus into the converter.

[0080] As shown in the following, Figure 2 the embodiment provides an optional way of calculating the first equivalent impedance, which can include the following steps:

[0081] Step 201, calculating the second equivalent impedance according to the steady-state operating point.

[0082] The second equivalent impedance is an equivalent impedance of positive and negative poles of a DC side of the receiving end system.

[0083] Step 202: calculating the first equivalent impedance according to the second equivalent impedance.

[0084] As shown in the following, Figure 3 the embodiment of the present application provides an optional way of calculating the second equivalent impedance, which comprises the following steps:

[0085] Step 301: performing small signal processing near the steady state operating point to obtain a first variation parameter.

[0086] The first variation parameter refers to a system variation parameter obtained by performing small signal processing near the steady state operating point, which comprises: taking the DC current variation Δi dc , the AC bus dq-axis voltage variation Δv d and Δv q as inputs, and taking the DC voltage variation Δu dc , the AC bus dq-axis current variation Δi d and Δi q , and the commutation overlap angle variation Δμ as outputs.

[0087] According to the small signal processing near different steady state operating points, the first variation parameter can be divided into: a sending end system positive pole variation parameter, a sending end system negative pole variation parameter, a receiving end system positive pole variation parameter, and a receiving end system negative pole variation parameter.

[0088] The process of small signal processing is the process of partial derivation of each output variable with respect to each input variable. In the following, the sending end system positive pole 12-pulse cycloconverter steady state operating point is taken as an example to perform small signal processing to obtain the sending end system positive pole variation parameter.

[0089] In the optional embodiment of the present application, the computer device can perform small signal processing according to the following equation:

[0090] The partial derivation of each input variable near the sending end system positive pole 12-pulse cycloconverter steady state operating point is as follows:

[0091]

[0092] Wherein, the subscript "0" represents the steady state operating value.

[0093] Considering the voltage drop of the transformer leakage inductance Lc caused by the change of the DC current i dc_r1 , the influence of i dc_r1 on u dc_r1 can be represented as:

[0094]

[0095] δ r1 As an intermediate variable, the change in DC voltage Δu dc The relationship between the input variables and the input variables can be expressed as:

[0096]

[0097] By i dc_r1 The steady-state expression can be simplified to a small-signal form to obtain the effect of changes in each input variable on δ. r1 Impact:

[0098] The last output variable Δμ r1 Equation μ r1 =δ r1 -α r1 Linearization yields its small-signal equation:

[0099]

[0100] Similarly, the above method can also be used to obtain the parameters of the change in the negative electrode of the sending system, the change in the positive electrode of the receiving system, and the change in the negative electrode of the receiving system.

[0101] Step 302: Calculate the second equivalent impedance based on the first variable parameter.

[0102] Below, as Figure 4 As shown, this application embodiment provides an optional method for calculating a second equivalent impedance based on a first changing parameter, wherein the method includes the following steps:

[0103] Step 401: Combine the equations of the positive and negative converters corresponding to the receiving-end system, the equations of the positive and negative control systems corresponding to the receiving-end system, and the equations of the AC power grid corresponding to the receiving-end system to obtain the first set of equations.

[0104] Step 402: Set the change in DC current of the receiving system in the first change parameter to 1, and substitute the first change parameter into the first set of equations to obtain the second change parameter.

[0105] Step 403: Calculate the second equivalent impedance based on the second variable parameter.

[0106] The second equivalent impedance refers to the DC equivalent impedance of the positive and negative terminals of the receiving end system.

[0107] The receiving-end and sending-end systems have a total of four converters, including the positive and negative converters for both the receiving and sending systems. Correspondingly, there are four converter equations: the equations for the positive and negative converters for both the receiving and sending systems.

[0108]

[0109]

[0110] Among them, K r1 It is the equation of the positive pole converter of the sending-end system, K r2 It is the equation of the negative pole converter of the sending-end system, K i1 It is the equation of the positive converter of the receiving-end system, K i2 These are the equations for the negative pole converter of the receiving-end system. These four converter equations are all 4x4 constant matrices, representing the transmission relationship between the input and output of each converter. In bipolar symmetrical operation, K... r1 =K r2 K i1 =K i2 .

[0111] In an optional embodiment of this application, the computer device can calculate the second equivalent impedance according to the following equation:

[0112]

[0113] Among them, Z acdd_i Z acdq_i Z acqd_i Z acqq_i G represents the equivalent impedance of the AC grid from the AC bus of the receiving system to the AC grid of the receiving system in the dq axis. c_i G represents the constant voltage control transfer function of the converter in the receiving-end system. pll_i This represents the transfer function of the phase-locked loop in the receiving-end system.

[0114] Solving the first system of equations yields 12 variables for the receiving-end system. Δu dc_i1 , Δu dc_i2 , Δi d_i1 , Δi q_i2 , Δα i1 , Δα i2 , Δδ i1 , Δδ i2 Δv d_i1 Δv q_i2 ), which is the second variable parameter.

[0115] The formula for calculating the second equivalent impedance is:

[0116] Z dc_i =Δu dc_i1 +Δu dc_i2 ;

[0117] Below, as Figure 5As shown, this application embodiment provides an optional method for calculating a first equivalent impedance based on a second equivalent impedance, wherein the method includes the following steps:

[0118] Step 501: Perform π-type equivalent processing on the DC line connecting the receiving end system and the sending end system to obtain the equivalent impedance calculation formula.

[0119] Step 502: Substitute the second equivalent impedance into the equivalent impedance calculation formula to obtain the first equivalent impedance.

[0120] The first equivalent impedance refers to the DC equivalent impedance of the positive and negative terminals of the sending-end system.

[0121] In an optional embodiment of this application, the computer device can perform Π-type equivalent processing according to the following method to obtain the impedance calculation formula:

[0122] The DC line connecting the sending and receiving ends is equivalent to a π-type line, such as... Figure 6 As shown. In bipolar symmetrical operation, the positive and negative lines have the same parameters and are connected by a ground wire. The currents flowing through the ground wire are equal in magnitude and opposite in direction, which is equivalent to being in series.

[0123] The formula for calculating the equivalent impedance is:

[0124] Z dc_r =(Z dc_i / / 2Z1+2Z2) / / 2Z1;

[0125] Substituting the second equivalent impedance into the equivalent impedance calculation formula yields the first equivalent impedance.

[0126] Below, as Figure 7 As shown, this application provides an optional method for calculating the positive and negative AC impedances of the d-axis and the positive and negative AC impedances of the q-axis, which includes the following steps:

[0127] Step 701: Combine the equations of the positive and negative converters corresponding to the sending-end system, the equations of the positive and negative control systems corresponding to the sending-end system, and the equations of the DC grid corresponding to the sending-end system to obtain the second set of equations.

[0128] Step 702: Substitute the first equivalent impedance and the first variable parameter into the second set of equations to obtain the positive and negative AC impedances of the d-axis and the positive and negative AC impedances of the q-axis.

[0129] Below, this application provides an optional method for calculating the positive and negative AC impedance of the d-axis, wherein the method includes the following steps:

[0130] The first equivalent impedance and the first variation parameter are substituted into the second equation set, and the variation of the d-axis voltage of the AC bus of the sending end system is 1 and the variation of the q-axis voltage of the AC bus of the sending end system is 0, to obtain the positive and negative pole AC impedance of the d-axis.

[0131] In an optional embodiment of the present application, the computer device can calculate the positive and negative pole AC impedance of the d-axis according to the following equation:

[0132] The above equations are combined to obtain a second equation set, and Δv d_r = 1 and Δv q_r = 0.

[0133]

[0134] wherein G c_r represents the sending end system converter constant current control transfer function, G pll_r represents the sending end system phase-locked loop transfer function.

[0135] Solving the second equation set can obtain 12 variables of the sending end system, including: Δu dc_r1 , Δu dc_r2 , Δi d_r1 , Δi q_r2 , Δα r1 , Δα r2 , Δδ r1 , Δδ r2 , Δv d_r1 , Δv q_r2 . The calculation formula of the positive and negative pole AC impedance of the d-axis is:

[0136]

[0137] Next, an optional way of calculating the positive and negative pole AC impedance of the q-axis is provided in the embodiments of the present application, and the way includes the following steps:

[0138] The first equivalent impedance and the first variation parameter are substituted into the second equation set, and the variation of the d-axis voltage of the AC bus of the sending end system is 0 and the variation of the q-axis voltage of the AC bus of the sending end system is 1, to obtain the positive and negative pole AC impedance of the q-axis.

[0139] In an optional embodiment of the present application, the computer device can calculate the positive and negative pole AC impedance of the q-axis according to the following equation:

[0140] The above equations are combined to obtain a second equation set, and Δv d_r = 0 and Δv q_r = 1.

[0141]

[0142] Solving the second equation set can obtain 12 variables of the sending end system, including: Δu dc_r1 , Δu dc_r2 , Δi d_r1 , Δi q_r2 , Δα r1 , Δα r2 , Δδ r1 , Δδ r2 , Δv d_r1 , Δv q_r2 ). The calculation formula of the positive and negative electrode alternating current impedance is:

[0143]

[0144] As shown in Figure 8 , the embodiment of the present application provides a stability determination method, comprising the following steps:

[0145] Step 801, calculating a steady state working point of a high voltage direct current transmission system according to system parameters in the high voltage direct current transmission system.

[0146] Step 802, performing small signal processing near the steady state working point to obtain a first variation parameter.

[0147] Step 803, obtaining a first equation set by simultaneously solving positive and negative electrode converter equations corresponding to the receiving end system, positive and negative electrode control system equations corresponding to the receiving end system, and alternating current grid equations corresponding to the receiving end system.

[0148] Step 804, setting a receiving end system direct current variation in the first variation parameter as 1, and substituting the first variation parameter into the first equation set to obtain a second variation parameter.

[0149] Step 805, calculating a second equivalent impedance according to the second variation parameter.

[0150] Step 806, performing π type equivalent processing on a direct current line connecting the receiving end system and the sending end system to obtain an equivalent impedance calculation formula.

[0151] Step 807, substituting the second equivalent impedance into the equivalent impedance calculation formula to obtain the first equivalent impedance.

[0152] Step 808, obtaining a second equation set by simultaneously solving positive and negative electrode converter equations corresponding to the sending end system, positive and negative electrode control system equations corresponding to the sending end system, and direct current grid equations corresponding to the sending end system.

[0153] Step 809, substituting the first equivalent impedance and the first change parameter into the second equation set to obtain the positive and negative electrode alternating current impedance of the d-axis and the positive and negative electrode alternating current impedance of the q-axis.

[0154] Substituting the first equivalent impedance and the first change parameter into the second equation set, and letting the alternating current bus d-axis voltage change of the sending end system be 1 and the alternating current bus q-axis voltage change of the sending end system be 0, the positive and negative electrode alternating current impedance of the d-axis is obtained.

[0155] Substituting the first equivalent impedance and the first change parameter into the second equation set, and letting the alternating current bus d-axis voltage change of the sending end system be 0 and the alternating current bus q-axis voltage change of the sending end system be 1, the positive and negative electrode alternating current impedance of the q-axis is obtained.

[0156] Step 810, transforming the positive and negative electrode alternating current impedance of the d-axis and the positive and negative electrode alternating current impedance of the q-axis to the αβ coordinate system through coordinate transformation, and performing stability analysis on the high-voltage direct current power transmission system.

[0157] It should be understood that, although each step in the flowchart involved in each embodiment as described above is displayed in sequence according to the direction of the arrow, these steps are not necessarily executed in sequence according to the direction of the arrow. Unless otherwise specified herein, the execution of these steps is not strictly limited in sequence, and these steps can be executed in other sequences. Moreover, at least part of the steps in the flowchart involved in each embodiment as described above can include multiple steps or multiple stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution sequence of these steps or stages is not necessarily sequential, but can be executed alternately or alternately with at least part of other steps or steps or stages in other steps.

[0158] Based on the same inventive concept, the embodiments of the present application also provide a stability determination device for implementing the above-mentioned stability determination method. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme described in the above method, so the specific limitations in one or more stability determination device embodiments provided below can refer to the limitations of the stability determination method in the above text, which will not be repeated here.

[0159] In one embodiment, as shown in Figure 9 a stability determination device 900 is provided, comprising a first calculation module 901, a second calculation module 902 and a third calculation module 903, wherein:

[0160] The first calculation module 901 is configured to calculate a steady state operating point of a high voltage direct current (HVDC) power transmission system according to system parameters of the HVDC power transmission system, the HVDC power transmission system comprising a sending end system and a receiving end system.

[0161] The second calculation module 902 is configured to calculate a first equivalent impedance according to the steady state operating point, the first equivalent impedance being a bipolar equivalent impedance of a direct current (DC) side of the sending end system.

[0162] The third calculation module 903 is configured to calculate a bipolar alternating current (AC) impedance of a d-axis and a bipolar AC impedance of a q-axis of the HVDC power transmission system according to the first equivalent impedance, and perform stability analysis on the HVDC power transmission system according to the bipolar AC impedance of the d-axis and the bipolar AC impedance of the q-axis.

[0163] In one of the embodiments, the second calculation module 902 comprises a first calculation unit configured to calculate a second equivalent impedance according to the steady state operating point, the second equivalent impedance being a positive and negative pole equivalent impedance of a DC side of the receiving end system; and a second calculation unit configured to calculate the first equivalent impedance according to the second equivalent impedance.

[0164] In one of the embodiments, the first calculation unit is specifically configured to perform small signal processing around the steady state operating point to obtain a first variation parameter, and calculate the second equivalent impedance according to the first variation parameter.

[0165] In one of the embodiments, the first calculation unit is specifically configured to obtain a first equation set by simultaneously solving a positive and negative pole converter equation corresponding to the receiving end system, a positive and negative pole control system equation corresponding to the receiving end system, and an AC power grid equation corresponding to the receiving end system; set a DC current variation parameter of the receiving end system in the first variation parameter to 1, and substitute the first variation parameter into the first equation set to obtain a second variation parameter; and calculate the second equivalent impedance according to the second variation parameter.

[0166] In one of the embodiments, the second calculation unit is specifically configured to perform Π type equivalent processing on a DC line connecting the receiving end system and the sending end system to obtain an equivalent impedance calculation formula; and substitute the second equivalent impedance into the equivalent impedance calculation formula to obtain the first equivalent impedance.

[0167] In one of the embodiments, the third calculation module 903 comprises:

[0168] a third calculation unit configured to obtain a second equation set by simultaneously solving a positive and negative pole converter equation corresponding to the sending end system, a positive and negative pole control system equation corresponding to the sending end system, and a DC power grid equation corresponding to the sending end system;

[0169] The fourth computing unit is configured to substitute the first equivalent impedance and the first variation parameter into the second equation set to obtain the positive and negative electrode alternating current impedance of the d-axis and the positive and negative electrode alternating current impedance of the q-axis.

[0170] In one of the embodiments, the fourth computing unit is specifically configured to substitute the first equivalent impedance and the first variation parameter into the second equation set, and set the alternating current bus d-axis voltage variation of the sending end system as 1 and the alternating current bus q-axis voltage variation of the sending end system as 0 to obtain the positive and negative electrode alternating current impedance of the d-axis; substitute the first equivalent impedance and the first variation parameter into the second equation set, and set the alternating current bus d-axis voltage variation of the sending end system as 0 and the alternating current bus q-axis voltage variation of the sending end system as 1 to obtain the positive and negative electrode alternating current impedance of the q-axis.

[0171] The modules in the stability determination apparatus can be implemented by software, hardware, or a combination thereof. The modules can be embedded in or independent of a processor in a computer device in hardware form, or stored in a memory in the computer device in software form, so as to be called and executed by the processor to perform the operations corresponding to the modules.

[0172] In one embodiment, a computer device is provided, which can be a server. An internal structure diagram of the computer device can be as shown in Figure 10 The computer device includes a processor, a memory, and a network interface connected through a system bus. The processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for running the operating system and the computer program in the non-volatile storage medium. The database of the computer device is configured to store data. The network interface of the computer device is configured to communicate with an external terminal through a network connection. The computer program is executed by the processor to implement a stability determination method.

[0173] In one embodiment, a computer device is provided, which can be a terminal. An internal structure diagram of the computer device can be as shown in Figure 11As shown in the figure. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected by a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used for wired or wireless communication with external terminals. Wireless communication can be achieved through WIFI, mobile cellular network, NFC (Near Field Communication) or other technologies. The computer program is executed by the processor to implement a stability determination method. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen. The input device of the computer device can be a touch layer overlaid on the display screen, or a key, trackball or touchpad arranged on the computer device shell, or an external keyboard, touchpad or mouse, etc.

[0174] Those skilled in the art can understand that, Figure 10 Or Figure 11 The structure shown in the figure is only a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the computer device to which the scheme of the present application is applied. The specific computer device can include more or fewer components than those shown in the figure, or combine certain components, or have a different component arrangement.

[0175] In one embodiment, a computer device is provided, comprising a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the following steps:

[0176] According to the system parameters in the high-voltage direct-current power transmission system, the steady-state operating point of the high-voltage direct-current power transmission system is calculated, the high-voltage direct-current power transmission system includes a sending end system and a receiving end system, and the steady-state operating point includes a first steady-state operating point of the positive and negative poles of the sending end system and a second steady-state operating point of the positive and negative poles of the receiving end system; according to the steady-state operating point, a first equivalent impedance is calculated, the first equivalent impedance is the positive and negative pole equivalent impedance of the sending end system on the direct-current side; according to the first equivalent impedance, the positive and negative pole AC impedances of the d-axis and the positive and negative pole AC impedances of the q-axis in the high-voltage direct-current power transmission system are calculated, and the high-voltage direct-current power transmission system is analyzed and processed according to the positive and negative pole AC impedances of the d-axis and the positive and negative pole AC impedances of the q-axis.

[0177] In one embodiment, the processor executing the computer program further implements the following steps: according to the steady-state operating point, a second equivalent impedance is calculated, the second equivalent impedance is the bipolar equivalent impedance of the receiving end system on the direct-current side; according to the second equivalent impedance, the first equivalent impedance is calculated.

[0178] In one embodiment, the processor, when executing the computer program, further implements the following steps: performing small signal processing on the steady state operating point to obtain a first variation parameter; and calculating the second equivalent impedance according to the first variation parameter.

[0179] In one embodiment, the processor, when executing the computer program, further implements the following steps: obtaining a first equation set by simultaneously solving the converter equation corresponding to the receiving end system, the control system equation corresponding to the receiving end system, and the AC power grid equation corresponding to the receiving end system; obtaining a second variation parameter by setting the receiving end system DC current variation in the first variation parameter to 1 and substituting the first variation parameter into the first equation set; and calculating the second equivalent impedance according to the second variation parameter.

[0180] In one embodiment, the processor, when executing the computer program, further implements the following steps: performing π-type equivalent processing on the DC line connecting the receiving end system and the sending end system to obtain an equivalent impedance calculation formula; and substituting the second equivalent impedance into the equivalent impedance calculation formula to obtain the first equivalent impedance.

[0181] In one embodiment, the processor, when executing the computer program, further implements the following steps: obtaining a second equation set by simultaneously solving the converter equation corresponding to the sending end system, the control system equation corresponding to the sending end system, and the DC power grid equation corresponding to the sending end system; and substituting the first equivalent impedance and the first variation parameter into the second equation set to obtain the bipolar AC impedance of the d-axis and the bipolar AC impedance of the q-axis.

[0182] In one embodiment, the processor, when executing the computer program, further implements the following steps: substituting the first equivalent impedance and the first variation parameter into the second equation set, setting the AC bus d-axis voltage variation of the sending end system to 1 and the AC bus q-axis voltage variation of the sending end system to 0 to obtain the bipolar AC impedance of the d-axis; and substituting the first equivalent impedance and the first variation parameter into the second equation set, setting the AC bus d-axis voltage variation of the sending end system to 0 and the AC bus q-axis voltage variation of the sending end system to 1 to obtain the bipolar AC impedance of the q-axis.

[0183] In one embodiment, a computer readable storage medium is provided, which stores a computer program. The computer program is executed by a processor to implement the following steps:

[0184] The steady state operating point of the high voltage direct current power transmission system is calculated according to system parameters in the high voltage direct current power transmission system, the high voltage direct current power transmission system comprising a sending end system and a receiving end system; a first equivalent impedance is calculated according to the steady state operating point, the first equivalent impedance being a bipolar equivalent impedance of a direct current side of the sending end system; bipolar alternating current impedances of a d-axis and a q-axis in the high voltage direct current power transmission system are calculated according to the first equivalent impedance, and stability analysis and processing of the high voltage direct current power transmission system are performed according to the bipolar alternating current impedances of the d-axis and the q-axis.

[0185] In one embodiment, the computer program, when executed by the processor, further implements the following steps: a second equivalent impedance is calculated according to the steady state operating point, the second equivalent impedance being a bipolar equivalent impedance of a direct current side of the receiving end system; and the first equivalent impedance is calculated according to the second equivalent impedance.

[0186] In one embodiment, the computer program, when executed by the processor, further implements the following steps: small signal processing is performed near the steady state operating point to obtain a first variation parameter; and the second equivalent impedance is calculated according to the first variation parameter.

[0187] In one embodiment, the computer program, when executed by the processor, further implements the following steps: a first equation set is obtained by simultaneously solving a converter equation corresponding to the receiving end system, a control system equation corresponding to the receiving end system and an alternating current power grid equation corresponding to the receiving end system; a receiving end system direct current current variation in the first variation parameter is set to 1, and the first variation parameter is substituted into the first equation set to obtain a second variation parameter; and the second equivalent impedance is calculated according to the second variation parameter.

[0188] In one embodiment, the computer program, when executed by the processor, further implements the following steps: a π-type equivalent processing is performed on a direct current line connecting the receiving end system and the sending end system to obtain an equivalent impedance calculation formula; and the second equivalent impedance is substituted into the equivalent impedance calculation formula to obtain the first equivalent impedance.

[0189] In one embodiment, the computer program, when executed by the processor, further implements the following steps: a second equation set is obtained by simultaneously solving a converter equation corresponding to the sending end system, a control system equation corresponding to the sending end system and a direct current power grid equation corresponding to the sending end system; and the first equivalent impedance and the first variation parameter are substituted into the second equation set to obtain the bipolar alternating current impedances of the d-axis and the q-axis.

[0190] In one embodiment, the computer program, when executed by the processor, further implements the following steps: substituting the first equivalent impedance and the first variation parameter into the second equation set, and setting the variation of the d-axis voltage of the AC bus of the sending end system as 1 and the variation of the q-axis voltage of the AC bus of the sending end system as 0 to obtain the bipolar AC impedance of the d-axis; and substituting the first equivalent impedance and the first variation parameter into the second equation set, and setting the variation of the d-axis voltage of the AC bus of the sending end system as 0 and the variation of the q-axis voltage of the AC bus of the sending end system as 1 to obtain the bipolar AC impedance of the q-axis.

[0191] In one embodiment, a computer program product is provided, comprising a computer program which, when executed by a processor, implements the following steps:

[0192] According to system parameters in a high-voltage direct-current power transmission system, a steady-state operating point of the high-voltage direct-current power transmission system is calculated, the high-voltage direct-current power transmission system comprising a sending end system and a receiving end system; according to the steady-state operating point, a first equivalent impedance is calculated, the first equivalent impedance being a bipolar equivalent impedance of a direct-current side of the sending end system; according to the first equivalent impedance, bipolar AC impedances of a d-axis and a q-axis in the high-voltage direct-current power transmission system are calculated, and according to the bipolar AC impedances of the d-axis and the q-axis, stability analysis and processing of the high-voltage direct-current power transmission system are performed.

[0193] In one embodiment, the computer program, when executed by the processor, further implements the following steps: according to the steady-state operating point, a second equivalent impedance is calculated, the second equivalent impedance being a bipolar equivalent impedance of a direct-current side of the receiving end system; and according to the second equivalent impedance, the first equivalent impedance is calculated.

[0194] In one embodiment, the computer program, when executed by the processor, further implements the following steps: small signal processing is performed in the vicinity of the steady-state operating point to obtain a first variation parameter; and according to the first variation parameter, the second equivalent impedance is calculated.

[0195] In one embodiment, the computer program, when executed by the processor, further implements the following steps: a first equation set is obtained by simultaneously solving a converter equation corresponding to the receiving end system, a control system equation corresponding to the receiving end system, and an AC power grid equation corresponding to the receiving end system; the receiving end system direct-current current variation parameter in the first variation parameter is set as 1, and the first variation parameter is substituted into the first equation set to obtain a second variation parameter; and according to the second variation parameter, the second equivalent impedance is calculated.

[0196] In one embodiment, the computer program, when executed by the processor, further implements the following steps: a direct-current line connecting the receiving end system and the sending end system is subjected to π-type equivalent processing to obtain an equivalent impedance calculation formula; and the second equivalent impedance is substituted into the equivalent impedance calculation formula to obtain the first equivalent impedance.

[0197] In one embodiment, the computer program, when executed by the processor, further implements the following steps: obtaining a second equation group by simultaneously solving the converter equation corresponding to the sending end system, the control system equation corresponding to the sending end system, and the DC power grid equation corresponding to the sending end system; and substituting the first equivalent impedance and the first variation parameter into the second equation group to obtain the bipolar AC impedance of the d-axis and the bipolar AC impedance of the q-axis.

[0198] In one embodiment, the computer program, when executed by the processor, further implements the following steps: substituting the first equivalent impedance and the first variation parameter into the second equation group, and setting the variation of the d-axis voltage of the AC bus of the sending end system to 1 and the variation of the q-axis voltage of the AC bus of the sending end system to 0 to obtain the bipolar AC impedance of the d-axis; and substituting the first equivalent impedance and the first variation parameter into the second equation group, and setting the variation of the d-axis voltage of the AC bus of the sending end system to 0 and the variation of the q-axis voltage of the AC bus of the sending end system to 1 to obtain the bipolar AC impedance of the q-axis.

[0199] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer readable storage medium, and when executed, can include the processes of the above-mentioned embodiment methods. Any reference to memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical storage, high-density embedded non-volatile memory, resistive memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration but not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The database involved in the embodiments provided in the present application can include at least one of a relational database and a non-relational database. The non-relational database can include a distributed database based on a block chain, etc., without being limited thereto. The processor involved in the embodiments provided in the present application can be a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., without being limited thereto.

[0200] Any combination of the technical features of the above embodiments can be made. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combination of the technical features does not exist, it should be considered as the scope of the present application.

[0201] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A stability determination method characterized by, The method comprises: calculating a steady state operating point of a high voltage direct current power transmission system according to system parameters in the high voltage direct current power transmission system, the high voltage direct current power transmission system comprising a sending end system and a receiving end system, the steady state operating point comprising a first steady state operating point of positive and negative poles of the sending end system and a second steady state operating point of positive and negative poles of the receiving end system; carrying out a small signal processing near the steady state operating point to obtain a first variation parameter; calculating a second equivalent impedance according to the first variation parameter, the second equivalent impedance being equivalent impedance of positive and negative poles of a direct current side of the receiving end system; calculating a first equivalent impedance according to the second equivalent impedance, the first equivalent impedance being equivalent impedance of positive and negative poles of a direct current side of the sending end system; obtaining a second equation group by simultaneously solving positive and negative pole converter equations corresponding to the sending end system, positive and negative pole control system equations corresponding to the sending end system and direct current grid equations corresponding to the sending end system; substituting the first equivalent impedance and the first variation parameter into the second equation group to obtain positive and negative pole alternating current impedances of a d-axis and positive and negative pole alternating current impedances of a q-axis, and carrying out stability analysis on the high voltage direct current power transmission system according to the positive and negative pole alternating current impedances of the d-axis and the positive and negative pole alternating current impedances of the q-axis.

2. The method of claim 1, wherein, The calculating of the second equivalent impedance according to the first variation parameter comprises: obtaining a first equation group by simultaneously solving positive and negative pole converter equations corresponding to the receiving end system, positive and negative pole control system equations corresponding to the receiving end system and alternating current grid equations corresponding to the receiving end system; setting a direct current current variation of the receiving end system in the first variation parameter as 1 and substituting the first variation parameter into the first equation group to obtain a second variation parameter; calculating the second equivalent impedance according to the second variation parameter.

3. The method of claim 1, wherein, The calculating of the first equivalent impedance according to the second equivalent impedance comprises: carrying out π-type equivalent processing on a direct current line connecting the receiving end system and the sending end system to obtain an equivalent impedance calculation formula; substituting the second equivalent impedance into the equivalent impedance calculation formula to obtain the first equivalent impedance.

4. The method of claim 1, wherein, The substituting of the first equivalent impedance and the first variation parameter into the second equation group to obtain the positive and negative pole alternating current impedances of the d-axis and the positive and negative pole alternating current impedances of the q-axis comprises: substituting the first equivalent impedance and the first variation parameter into the second equation group and setting a d-axis voltage variation of an alternating current bus of the sending end system as 1 and a q-axis voltage variation of the alternating current bus of the sending end system as 0 to obtain the positive and negative pole alternating current impedances of the d-axis; substituting the first equivalent impedance and the first variation parameter into the second equation group and setting the d-axis voltage variation of the alternating current bus of the sending end system as 0 and the q-axis voltage variation of the alternating current bus of the sending end system as 1 to obtain the positive and negative pole alternating current impedances of the q-axis.

5. The method of claim 1, wherein, The first steady state operating point comprises a sending end system positive pole 12-pulse converter steady state operating point and a sending end system negative pole 12-pulse converter steady state operating point. The second steady state operating point includes a positive pole 12 pulse converter steady state operating point of the receiving end system and a negative pole 12 pulse converter steady state operating point of the receiving end system.

6. The method of claim 1, wherein, The method for calculating the steady state operating point of the high voltage direct current power transmission system according to system parameters in the high voltage direct current power transmission system comprises the following steps. The steady state operating point of the high voltage direct current power transmission system is calculated based on the average value method according to the system parameters.

7. A stability determination apparatus characterized by comprising: The device comprises: The first calculation module is configured to calculate the steady state operating point of the high voltage direct current power transmission system according to system parameters in the high voltage direct current power transmission system, wherein the high voltage direct current power transmission system comprises a sending end system and a receiving end system, and the steady state operating point comprises first steady state operating points of positive and negative poles of the sending end system and second steady state operating points of positive and negative poles of the receiving end system. The first calculation unit is configured to perform small signal processing in the vicinity of the steady state operating point to obtain a first variation parameter, and calculate a second equivalent impedance according to the first variation parameter, wherein the second equivalent impedance is an equivalent impedance of positive and negative poles on a direct current side of the receiving end system. The second calculation unit is configured to calculate a first equivalent impedance according to the second equivalent impedance, wherein the first equivalent impedance is an equivalent impedance of positive and negative poles on a direct current side of the sending end system. The third calculation unit is configured to obtain a second equation set by simultaneously solving a positive and negative pole converter equation corresponding to the sending end system, a positive and negative pole control system equation corresponding to the sending end system, and a direct current power grid equation corresponding to the sending end system. The fourth calculation unit is configured to substitute the first equivalent impedance and the first variation parameter into the second equation set to obtain positive and negative pole alternating current impedances on a d-axis and positive and negative pole alternating current impedances on a q-axis, and perform stability analysis on the high voltage direct current power transmission system according to the positive and negative pole alternating current impedances on the d-axis and the positive and negative pole alternating current impedances on the q-axis.

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

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

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

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