A method, device and electronic device for judging the state of a multi-feed system

Abstract

The present application discloses a state judgment method, device and electronic device for a multi-feedback system. The method and device are applied to the electronic device, specifically, to establish a fourth-order Jacobian matrix based on the per-unit quasi-steady-state equations of a single-feedback system; to perform matrix transformation on the fourth-order Jacobian matrix to obtain a power bifurcation Jacobian matrix and a static voltage stability Jacobian matrix for four different control modes; to perform calculations based on the elements of the power bifurcation Jacobian matrix to obtain a first sensitivity and a second sensitivity; and to judge the power bifurcation characteristics and static voltage stability of the AC / DC system based on the first sensitivity and the second sensitivity. This scheme calculates the sensitivity of the DC transmission power to the DC current and the sensitivity of the node reactive power to the AC voltage based on the four-node pressure block matrix, thereby achieving effective judgment on whether the power of the multi-feedback system is controllable and the static voltage is stable.

Description

Technical Field

[0001] The present application relates to the technical field of electric power equipment, and more specifically, to a state judgment method, device and electronic equipment for a multi-feedback system. Background Art

[0002] The MIDC system (multi-infeed LCC-HVDC system) formed by multi-circuit grid-commutated high-voltage direct current transmission LCC-HVDC feeding into the same AC grid has become one of the main representative types of my country's new power system. Its safe and stable operation is the key to ensuring the realization of the strategic goals of "carbon peak and carbon neutrality". The complex interactions between DC systems and between AC and DC systems in multi-infeed systems are the main factors affecting their stable operation. According to the two stable forms of power bifurcation or static voltage stability, the interactions are divided into two types: power interaction and voltage interaction. Accurately measuring the interactions in multi-infeed systems is very important for system planning and operation.

[0003] According to the quasi-steady-state equations of the AC / DC system, existing studies have established the third-order Jacobian matrix (also known as the power bifurcation Jacobian matrix) and the second-order Jacobian matrix (also known as the static voltage stability Jacobian matrix) to define the power interaction factor and the voltage interaction factor. Based on the relationship between the voltage interaction factor and the elements of the two-order Jacobian matrix, the CIGRE standard model is used to analyze the numerical characteristics of the power-voltage external characteristics of LCC-HVDC under three different control modes.

[0004] However, existing studies have failed to systematically explain the transformation relationship between the power bifurcation Jacobian matrix and the static voltage stability Jacobian matrix, nor have they proposed a Jacobian matrix modeling method that can unify the four common control modes of constant power constant arc angle (CP-CEA), constant current constant arc angle (CC-CEA), constant power constant voltage (CP-CV) and constant current constant voltage (CC-CV). As a result, it is difficult to effectively compare the analysis results under different control modes and it is impossible to accurately judge whether the system is power controllable and static voltage stable. Summary of the invention

[0005] In view of this, the present application provides a state judgment method, device and electronic device of a multi-infeed system, which are used to compare analysis results under different control modes to accurately judge whether the system is power controllable and the static voltage is stable.

[0006] In order to achieve the above objectives, the proposed solution is as follows:

[0007] A method for determining the state of a multi-feedback system is applied to electronic equipment. The method comprises the following steps:

[0008] Based on the per-unit quasi-steady-state equations of the single-infeed system, a fourth-order Jacobian matrix is ​​established with the micro-increments of the cut-off angle, DC current, AC voltage and power angle of the single-infeed system as independent variables, and the micro-increments of the DC voltage, DC transmission power, node reactive power and node active power of the single-infeed system as dependent variables;

[0009] Performing matrix transformation on the fourth-order Jacobian matrix to obtain power bifurcation Jacobian matrices and static voltage stability Jacobian matrices of four different control modes;

[0010] Calculate according to the elements of the power bifurcation Jacobian matrix to obtain the first sensitivity of the DC transmission power to the DC current in the single-feed system

[0011] Calculating according to the elements of the static voltage stability Jacobian matrix, obtaining a second sensitivity of reactive power emitted by the DC system in the single-feed system to the AC voltage;

[0012] The power bifurcation characteristics and static voltage stability of the AC / DC system are determined according to the first sensitivity and the second sensitivity.

[0013] Optionally, the per-unit quasi-steady-state equations are:

[0014]

[0015] P d =U d I d

[0016]

[0017]

[0018] P=P d -UEsin(θ) / Z

[0019] Q=Q d +ωB c U 2 -(U 2 -UEcos(θ)) / Z

[0020] Among them, P d , U d ,I d , γ and x are the active power, voltage, current, turn-off angle and commutation reactance on the DC side respectively. The AC power grid is represented by a voltage source E and an impedance Z in series after the Thevenin equivalent. k is the ratio of the DC side voltage reference value to the AC measured voltage reference value.

[0021] Optionally, the fourth-order Jacobian matrix is ​​as follows:

[0022]

[0023] Optionally, the relationship between the micro-increment of the DC transmission power and the micro-increment of the DC current is:

[0024] △P d =J dc △I d

[0025] Among them, J dc is the first sensitivity,

[0026]

[0027] The relationship between the micro-increment of the node reactive power and the micro-increment of the AC voltage is:

[0028] △Q=J S △U / U

[0029] Among them, J s is the second sensitivity,

[0030]

[0031] Optionally, judging the power bifurcation characteristics and static voltage stability of the AC / DC system according to the first sensitivity and the second sensitivity comprises the steps of:

[0032] When J dc When >0, it means that when the DC current is increased, the DC transmission power increases accordingly, and it is determined that the system has not lost power controllability;

[0033] When J dc When <0, it means that when the DC current is increased, the DC transmission power decreases instead, and the system reaches the power bifurcation point, and it is determined that the power controllability is lost;

[0034] When J s <0, it means that when the AC voltage decreases, the DC feed-in reactive power increases, and the static voltage is determined to be stable;

[0035] When J s When >0, it means that when the AC voltage decreases, the DC input reactive power also decreases, and the static voltage is determined to be unstable.

[0036] A state judgment device for a multi-feed system is applied to electronic equipment, and the state judgment device comprises:

[0037] A matrix building module is configured to establish a fourth-order Jacobian matrix based on a per-unit quasi-steady-state equation group of a single-feed system, with a cut-off angle, a DC current, an AC voltage and a micro-increment of a power angle of the single-feed system as independent variables, and with a DC voltage, a DC transmission power, a node reactive power and a node active power of the single-feed system as dependent variables;

[0038] A matrix transformation module is configured to perform matrix transformation on the fourth-order Jacobian matrix to obtain power bifurcation Jacobian matrices and static voltage stability Jacobian matrices of four different control modes;

[0039] The first calculation module is configured to calculate according to the elements of the power bifurcation Jacobian matrix to obtain a first sensitivity of the DC transmission power to the DC current in the single-feed system.

[0040] A second calculation module is configured to calculate according to the elements of the static voltage stability Jacobian matrix to obtain a second sensitivity of the reactive power generated by the DC system in the single-feed system to the AC voltage;

[0041] The judgment execution module is configured to judge the power bifurcation characteristics and static voltage stability of the AC / DC system according to the first sensitivity and the second sensitivity.

[0042] Optionally, the per-unit quasi-steady-state equations are:

[0043]

[0044] P d =U d I d

[0045]

[0046]

[0047] P=P d -UEsin(θ) / Z

[0048] Q=Q d +ωB c U 2 -(U 2 -UEcos(θ)) / Z

[0049] Among them, P d , U d ,I d , γ and x are the active power, voltage, current, turn-off angle and commutation reactance on the DC side respectively. The AC power grid is represented by a voltage source E and an impedance Z in series after the Thevenin equivalent. k is the ratio of the DC side voltage reference value to the AC measured voltage reference value.

[0050] Optionally, the fourth-order Jacobian matrix is ​​as follows:

[0051]

[0052] Optionally, the relationship between the micro-increment of the DC transmission power and the micro-increment of the DC current is:

[0053] △P d =J dc △I d

[0054] Among them, J dc is the first sensitivity,

[0055]

[0056] The relationship between the micro-increment of the node reactive power and the micro-increment of the AC voltage is:

[0057] △Q=J S △U / U

[0058] Among them, J s is the second sensitivity,

[0059]

[0060] Optionally, the judgment execution module includes:

[0061] The first determination unit is used when J dc >0, it is determined that the multi-feed system has not lost power controllability. dc <0, it is determined that the multi-feed system loses power controllability;

[0062] The second determination unit is used when J s <0, the static voltage of the multi-feed system is determined to be stable. s >0, it is determined that the static voltage of the multi-feed system is unstable.

[0063] An electronic device, characterized in that it comprises at least one processor and a memory connected to the processor, wherein:

[0064] The memory is used to store computer programs or instructions;

[0065] The processor is used to execute the computer program or instruction so that the electronic device implements the state determination method of the multi-feed system as described above.

[0066] It can be seen from the above technical scheme that the present application discloses a state judgment method, device and electronic device for a multi-feedback system. The method and device are applied to the electronic device, specifically, to establish a fourth-order Jacobian matrix based on the per-unit quasi-steady-state equation group of the single-feedback system; to perform matrix transformation on the fourth-order Jacobian matrix to obtain the power bifurcation Jacobian matrix and the static voltage stability Jacobian matrix of four different control modes; to calculate according to the elements of the power bifurcation Jacobian matrix to obtain the first sensitivity and the second sensitivity; to judge the power bifurcation characteristics and the static voltage stability of the AC / DC system according to the first sensitivity and the second sensitivity. This scheme calculates the sensitivity of the DC transmission power to the DC current and the sensitivity of the node reactive power to the AC voltage based on the four-node pressure block matrix, thereby realizing effective judgment on whether the multi-feedback system is power controllable and the static voltage is stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0068] Figure 1 A flow chart of a method for determining a state of a multi-feed system according to an embodiment of the present application;

[0069] Figure 2 A quasi-steady-state model of a LCC-HVDC single-feed system according to an embodiment of the present application;

[0070] Figure 3 The relationship between the four control modes and SCR in the simulation verification of the embodiment of this application;

[0071] Figure 4 The relationship between the four control modes and SCR in the simulation verification of the embodiment of this application;

[0072] Figure 5 A block diagram of a state determination device for a multi-feed system according to an embodiment of the present application;

[0073] Figure 6 A block diagram of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0074] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0075] Embodiment 1

[0076] Figure 1 Flow chart of a method for determining a state of a multi-input system according to an embodiment of the present application.

[0077] like Figure 1 As shown, the state judgment method provided in this embodiment is applied to an electronic device for judging the state of a multi-feed system. The electronic device here can be understood as a computer or server with data calculation and information processing capabilities. The state judgment method includes the following steps:

[0078] S1. Construct the fourth-order Jacobian matrix based on the single-feed system.

[0079] Based on the per-unit quasi-steady-state equations of the single-infeed system, a fourth-order Jacobian matrix is ​​established with the turn-off angle, DC current, AC voltage and slight increment of power angle of the single-infeed system as independent variables, and the DC voltage, DC transmission power, node reactive power and node active power of the single-infeed system as dependent variables.

[0080] The per-unit quasi-steady-state equations are as follows:

[0081]

[0082] P d =U d I d (2)

[0083]

[0084]

[0085] P=P d -UEsin(θ) / Z (5)

[0086] Q=Q d +ωB c U 2 -(U 2 -UEcos(θ)) / Z (6)

[0087] Among them, P d , U d ,I d, γ and x are the active power, voltage, current, turn-off angle and commutation reactance of the DC side respectively. The AC power grid is represented by the voltage source E and impedance Z in series after the Thevenin equivalent. k is the ratio of the DC side voltage reference value to the AC voltage reference value. Equations (1)-(4) represent the inverter port characteristics respectively, and equations (5) and (6) are the AC-DC system coupling characteristics. The above equations can be directly substituted into the per-unit values ​​of each variable for calculation.

[0088] The micro increments of the cut-off angle, DC current, AC voltage, and power angle are Δγ and ΔI. d , ΔU, Δθ are independent variables, with the DC voltage, DC transmission power, node reactive power, and node active power micro-increment ΔU d , ΔP d , ΔP, ΔQ are dependent variables, and the established fourth-order Jacobian matrix is ​​as follows:

[0089]

[0090] S2. Perform matrix transformation on the fourth-order Jacobian matrix.

[0091] Through the matrix transformation of the fourth-order Jacobian matrix, the power bifurcation Jacobian matrix PBJM and the static voltage stability Jacobian matrix SVSJM under four different control modes are obtained. The specific scheme is as follows:

[0092] The power bifurcation Jacobian matrix PBJM is obtained by transforming the fourth-order Jacobian matrix as follows:

[0093] Unified PBJM under CP / CC-CEA control method: Let Δγ = 0 in equation (7) and ignore J total The first row and column of:

[0094]

[0095] PBJM under CP / CC-CV control method: Let ΔU = 0 in equation (7) and make the left Schur complement to the lower right corner:

[0096]

[0097] By transforming the fourth-order Jacobian matrix as follows, the static voltage stability Jacobian matrix SVSJM is obtained:

[0098] For the CP-CEA control method, SVSJM is the result of schur complementation of PBJM to the lower right corner, which can be expressed as:

[0099]

[0100] For CC-CEA control mode, SVSJM is the result of PBJM after ignoring the first row and first column elements, which can be expressed as:

[0101]

[0102] For the CP-CV control method, SVSJM is the result of schur complementation of PBJM to the lower right corner, which can be expressed as:

[0103]

[0104] For CC-CV control mode, SVSJM is the result of PBJM after ignoring the first row and first column elements, which can be expressed as:

[0105]

[0106] S3. Calculate the first sensitivity of the DC transmission power to the DC current.

[0107] According to the elements of the power bifurcation Jacobian matrix, the first sensitivity J of the DC transmission power to the DC current is obtained. dc .

[0108] The relationship between the micro-increment of DC transmission power and the micro-increment of DC current is:

[0109] △P d =J dc △I d

[0110] in,

[0111]

[0112] S4. Calculate the second sensitivity of reactive power to AC voltage.

[0113] According to the elements of the static voltage stability Jacobian matrix, the second sensitivity J of the reactive power generated by the DC system in the multi-infeed system to the AC voltage is obtained. S ;

[0114] The relationship between the node reactive power micro-increment and the AC voltage micro-increment is:

[0115] △Q=J S △U / U

[0116] in,

[0117]

[0118] S5. Determine the power bifurcation characteristics and static voltage stability of the AC / DC system.

[0119] Based on the first sensitivity of DC transmission power to DC current, and the second sensitivity of reactive power emitted by the DC system to AC voltage, the power bifurcation stability and static voltage stability of the AC / DC system are determined through analysis and judgment.

[0120] When J dc >0, it means that when the DC current is increased, the DC transmission power increases accordingly, and it is determined that the multi-infeed system has not lost power controllability; when J dc When <0, it means that when the DC current is increased, the DC transmission power decreases instead, reaching the power bifurcation point, and it is determined that the multi-infeed system loses power controllability.

[0121] When J S <0, it means that when the AC voltage decreases, the DC feed-in reactive power increases, and the static voltage of the multi-feed system is determined to be stable; when J S When >0, it means that when the AC voltage decreases, the DC feed-in reactive power also decreases. At this time, it is determined that the static voltage of the multi-feed system is unstable.

[0122] It can be seen from the above technical scheme that this embodiment provides a state judgment method for a multi-feedback system, which is applied to electronic equipment, specifically establishing a fourth-order Jacobian matrix based on the per-unit quasi-steady-state equation group of a single-feedback system; performing matrix transformation on the fourth-order Jacobian matrix to obtain a power bifurcation Jacobian matrix and a static voltage stability Jacobian matrix of four different control modes; performing calculations based on the elements of the power bifurcation Jacobian matrix to obtain a first sensitivity and a second sensitivity; judging the power bifurcation characteristics and static voltage stability of the AC / DC system based on the first sensitivity and the second sensitivity. This scheme calculates the sensitivity of DC transmission power to DC current and the sensitivity of node reactive power to AC voltage based on a four-node pressure block matrix, thereby achieving effective judgment on whether the multi-feedback system is power controllable and static voltage stable.

[0123] In order to analyze the effectiveness of the 4th-order Jacobian matrix proposed in this application, the following Figure 2 The quasi-steady-state model of the LCC-HVDC single-feed system shown in the figure is used for matrix analysis and calculation.

[0124] The example adopts the CIGRE standard DC test system parameters, the DC side rated power is 1000MW, the DC side rated voltage is 500kV, the rated voltage of the inverter side AC system adopts the line voltage effective value of 230kV, the transformer ratio K=211.42 / 230, and the ratio of the AC and DC voltage reference values ​​k=500 / 230. It is assumed that the DC port voltage U=1, and in the subsequent analysis, the short circuit ratio (SCR) is used to measure the influence of the AC system strength on the interaction, and SCR=1 / Z.

[0125] Since the power bifurcation of the AC / DC system depends on the ability to maintain the positive feedback relationship between the DC transmission power and the DC current, it is necessary to control the J dc Compare and analyze. Calculate the J of CP-CEA / CC-CEA control mode dc =0.3998, J of CP-CV / CC-CV control method dc =1 (the AC system is a purely inductive network, and SCR = 3 at this time). By comparing the above two values, it can be seen that the CP-CV / CC-CV control method has a weaker power interaction than the CEA / CC-CEA control method, and the operating point is relatively far away from the power bifurcation point, so it has better power stability.

[0126] Attached Figure 3 The calculation results at different SCRs under CP-CEA / CC-CEA control mode and CP-CV / CC-CV control mode are given. Under CP-CV / CC-CV control mode, when SCR increases from 2 to 3, J dc2 It is always equal to 1, indicating that the system is not prone to power bifurcation; while in the CP-CEA / CC-CEA control mode, when SCR increases from 2 to 3, J dc1 From negative to positive, the critical short circuit ratio (CSCR) is approximately equal to 2, and the corresponding J dc1 =0, the system operates at the power bifurcation point.

[0127] Since the static voltage stability of the LCC-HVDC AC / DC system is affected by the sensitivity of the active power and reactive power on the inverter side to the commutation voltage amplitude, it is necessary to analyze the voltage sensitivity J′ of the single-feed system under the four control modes. PdU and J′ QdU The calculation results of voltage sensitivity of CIGRE standard DC test system under the above four control modes are shown in the following table:

[0128]

[0129] It can be seen from the table that only when the system is in the CP-CEA control mode, the sensitivity between the reactive power generated by the DC system and the voltage amplitude is positive, which indicates that when the system voltage drops, the DC will absorb more reactive power, aggravating the voltage drop on the AC side. The other three control modes all have good static voltage stability.

[0130] Attached Figure 4 Four control modes are given in s Calculation results at different SCR, where curve J s1 , Js2 , J s3 and J s4 They represent the calculation results under CP-CEA, CC-CEA, CP-CV and CC-CV control modes respectively. s <0, the system static voltage is stable. Figure 4 It can be seen that the static voltage stability margin of CP-CEA control is the smallest, and voltage stability problems are prone to occur. The stability margin of CC-CEA is in the middle, and the static voltage stability margin is the largest under CP-CV / CC-CV control mode. In addition, under CP-CEA control, when J s =0, the corresponding CSCR is also approximately 2.

[0131] It can be seen from the above implementation that the fourth-order Jacobian matrix unified modeling method of the present application can effectively analyze the power bifurcation / static voltage stability characteristics of the AC / DC system, and obtain the power bifurcation Jacobian matrix or static voltage stability Jacobian matrix of the four control modes through matrix transformation from the fourth-order Jacobian matrix, and then calculate the sensitivity of the DC transmission power to the DC current or the sensitivity of the node reactive power to the AC voltage, accurately judge whether the system is power controllable and the static voltage is stable, so that the system can operate safely and stably.

[0132] Embodiment 2

[0133] Figure 5 4 is a block diagram of a state determination device for a multi-input system according to an embodiment of the present application.

[0134] like Figure 5 As shown, the state judgment device provided in this embodiment is applied to an electronic device for judging the state of a multi-feedback system. The electronic device here can be understood as a computer or server with data calculation and information processing capabilities, and the device can be understood as a functional module in the computer or server or itself. The state judgment device includes a matrix construction module 10, a matrix transformation module 20, a first calculation module 30, a second calculation module 40 and a judgment execution module 50.

[0135] The matrix building block is used to build a fourth-order Jacobian matrix based on a single-feed system.

[0136] Based on the per-unit quasi-steady-state equations of the single-infeed system, a fourth-order Jacobian matrix is ​​established with the turn-off angle, DC current, AC voltage and slight increment of power angle of the single-infeed system as independent variables, and the DC voltage, DC transmission power, node reactive power and node active power of the single-infeed system as dependent variables.

[0137] The per-unit quasi-steady-state equations are as follows:

[0138]

[0139] P d =U d I d (9)

[0140]

[0141]

[0142] P=P d -UEsin(θ) / Z (12)

[0143] Q=Q d +ωB c U 2 -(U2-UEcos(θ)) / Z (13)

[0144] Among them, P d , U d ,I d , γ and x are the active power, voltage, current, turn-off angle and commutation reactance of the DC side respectively. The AC power grid is represented by the voltage source E and impedance Z in series after the Thevenin equivalent. k is the ratio of the DC side voltage reference value to the AC voltage reference value. Equations (1)-(4) represent the inverter port characteristics respectively, and equations (5) and (6) are the AC-DC system coupling characteristics. The above equations can be directly substituted into the per-unit values ​​of each variable for calculation.

[0145] The micro increments of the cut-off angle, DC current, AC voltage, and power angle are Δγ and ΔI. d , ΔU, Δθ are independent variables, with the DC voltage, DC transmission power, node reactive power, and node active power micro-increment ΔU d , ΔP d , ΔP, ΔQ are dependent variables, and the established fourth-order Jacobian matrix is ​​as follows:

[0146]

[0147] The matrix transformation module is used to perform matrix transformation on the fourth-order Jacobian matrix.

[0148] Through the matrix transformation of the fourth-order Jacobian matrix, the power bifurcation Jacobian matrix PBJM and the static voltage stability Jacobian matrix SVSJM under four different control modes are obtained. The specific scheme is as follows:

[0149] The power bifurcation Jacobian matrix PBJM is obtained by transforming the fourth-order Jacobian matrix as follows:

[0150] Unified PBJM under CP / CC-CEA control method: Let Δγ = 0 in equation (7) and ignore J total The first row and column of:

[0151]

[0152] PBJM under CP / CC-CV control method: Let ΔU = 0 in equation (7) and make the left Schur complement to the lower right corner:

[0153]

[0154] By transforming the fourth-order Jacobian matrix as follows, the static voltage stability Jacobian matrix SVSJM is obtained:

[0155] For the CP-CEA control method, SVSJM is the result of schur complementation of PBJM to the lower right corner, which can be expressed as:

[0156]

[0157] For CC-CEA control mode, SVSJM is the result of PBJM after ignoring the first row and first column elements, which can be expressed as:

[0158]

[0159] For the CP-CV control method, SVSJM is the result of schur complementation of PBJM to the lower right corner, which can be expressed as:

[0160]

[0161] For CC-CV control mode, SVSJM is the result of PBJM after ignoring the first row and first column elements, which can be expressed as:

[0162]

[0163] The first calculation module is used to calculate a first sensitivity of the DC transmission power to the DC current.

[0164] According to the elements of the power bifurcation Jacobian matrix, the first sensitivity J of the DC transmission power to the DC current is obtained. dc .

[0165] The relationship between the micro-increment of DC transmission power and the micro-increment of DC current is:

[0166] △P d =J dc △I d

[0167] in,

[0168]

[0169] The second calculation module is used to calculate a second sensitivity of reactive power to AC voltage.

[0170] According to the elements of the static voltage stability Jacobian matrix, the second sensitivity J of the reactive power generated by the DC system in the multi-infeed system to the AC voltage is obtained. S ;

[0171] The relationship between the node reactive power micro-increment and the AC voltage micro-increment is:

[0172] △Q=J S △U / U

[0173] in,

[0174]

[0175] The judgment execution module is used to judge the power bifurcation characteristics and static voltage stability of the AC / DC system.

[0176] According to the first sensitivity of DC transmission power to DC current and the second sensitivity of reactive power emitted by the DC system to AC voltage, the power bifurcation stability and static voltage stability of the AC / DC system are determined through analysis and judgment. The module includes a first determination unit and a second determination unit.

[0177] When J dc >0, it means that when the DC current is increased, the DC transmission power increases accordingly. At this time, the first determination unit determines that the multi-feed system has not lost power controllability; when J dc <0, it means that when the DC current is increased, the DC transmission power is reduced and reaches the power bifurcation point. At this time, the second determination unit determines that the multi-infeed system loses power controllability.

[0178] When J S <0, it means that when the AC voltage decreases, the DC feed-in reactive power increases, and the static voltage of the multi-feed system is determined to be stable; when J S When >0, it means that when the AC voltage decreases, the DC feed-in reactive power also decreases. At this time, it is determined that the static voltage of the multi-feed system is unstable.

[0179] It can be seen from the above technical scheme that this embodiment provides a state judgment device for a multi-feedback system, which is applied to electronic equipment, specifically to establish a fourth-order Jacobian matrix based on the per-unit quasi-steady-state equation group of a single-feedback system; perform matrix transformation on the fourth-order Jacobian matrix to obtain a power bifurcation Jacobian matrix and a static voltage stability Jacobian matrix of four different control modes; perform calculations based on the elements of the power bifurcation Jacobian matrix to obtain a first sensitivity and a second sensitivity; and judge the power bifurcation characteristics and static voltage stability of the AC / DC system based on the first sensitivity and the second sensitivity. This scheme calculates the sensitivity of DC transmission power to DC current and the sensitivity of node reactive power to AC voltage based on a four-section pressure block matrix, thereby achieving effective judgment on whether the multi-feedback system is power controllable and static voltage stable.

[0180] Embodiment 3

[0181] Figure 6 A block diagram of an electronic device according to an embodiment of the present application.

[0182] like Figure 6 As shown, the electronic device provided in this embodiment can be understood as a computer or server with data calculation and information processing capabilities, and the electronic device includes at least one processor 101 and a memory 102, which are connected via a data bus 103. The memory is used to store computer programs or instructions, and the processor is used to obtain corresponding computer programs or instructions, so that the electronic device implements the state judgment method of the multi-feed system provided in the first embodiment.

[0183] The state judgment method is specifically to establish a fourth-order Jacobian matrix based on the per-unit quasi-steady-state equations of the single-feed system; perform matrix transformation on the fourth-order Jacobian matrix to obtain the power bifurcation Jacobian matrix and the static voltage stability Jacobian matrix of four different control modes; calculate according to the elements of the power bifurcation Jacobian matrix to obtain the first sensitivity and the second sensitivity; judge the power bifurcation characteristics and static voltage stability of the AC / DC system according to the first sensitivity and the second sensitivity. This scheme calculates the sensitivity of DC transmission power to DC current and the sensitivity of node reactive power to AC voltage based on the four-node pressure block matrix, thereby realizing effective judgment on whether the multi-feed system is power controllable and static voltage stable.

[0184] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0185] It will be appreciated by those skilled in the art that the embodiments of the present invention may be provided as methods, devices, or computer program products. Therefore, the embodiments of the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the embodiments of the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0186] The embodiments of the present invention are described with reference to the flowcharts and / or block diagrams of the methods, terminal devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0187] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing terminal device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0188] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device so that a series of operating steps are executed on the computer or other programmable terminal device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable terminal device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0189] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0190] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0191] The technical solution provided by the present invention is introduced in detail above. Specific examples are used in this article to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for determining the state of a multi-feed system, applied to electronic equipment, characterized in that: The state determination method comprises the steps of: Based on the per-unit quasi-steady-state equations of the single-feed system, the micro-increments of the cut-off angle, DC current, AC voltage and power angle of the single-feed system are taken as independent variables, and the micro-increments of the DC voltage, DC transmission power, node reactive power and node active power of the single-feed system are taken as dependent variables. A fourth-order Jacobian matrix is ​​established. The per-unit quasi-steady-state equations are: P d =U d AND d P=P d -UEsin(θ) / Z Q=Q d +ωB c U 2 -(U 2 -UEcos(θ)) / Z Among them, P d , U d ,I d , γ and X are the active power, voltage, current, turn-off angle and commutation reactance of the DC side respectively. The AC power grid is represented by the voltage source E and the impedance Z in series after the Thevenin equivalent. k is the ratio of the DC side voltage reference value to the AC measurement voltage reference value. K is the transformer ratio. U is the DC port voltage. Performing matrix transformation on the fourth-order Jacobian matrix to obtain power bifurcation Jacobian matrices and static voltage stability Jacobian matrices of four different control modes; Calculating according to the elements of the power bifurcation Jacobian matrix, obtaining a first sensitivity of the DC transmission power to the DC current in the single-feed system; Calculating according to the elements of the static voltage stability Jacobian matrix, obtaining a second sensitivity of reactive power generated by the DC system in the single-feed system to the AC voltage; The power bifurcation characteristics and static voltage stability of the AC / DC system are determined according to the first sensitivity and the second sensitivity.

2. The state determination method according to claim 1, characterized in that: The fourth-order Jacobian matrix is ​​as follows: Among them, Δγ is the micro-increment of the shutdown angle, ΔId is the micro-increment of the DC current, ΔU is the micro-increment of the AC voltage, Δθ is the micro-increment of the power angle, ΔUd is the micro-increment of the DC voltage, ΔPd is the micro-increment of the DC transmission power, ΔP is the micro-increment of the node reactive power, ΔQ is the micro-increment of the node active power, and U is the DC port voltage.

3. The state determination method according to claim 1, characterized in that: The relationship between the micro-increment of the DC transmission power and the micro-increment of the DC current is: ΔP d =J dc ΔI d Among them, J dc is the first sensitivity, The relationship between the micro-increment of the node reactive power and the micro-increment of the AC voltage is: ΔQ=J S ΔU / U Among them, J s is the second sensitivity, Among them, ΔId is the micro-increment of DC current, ΔU is the micro-increment of AC voltage, ΔPd is the micro-increment of DC transmission power, ΔQ is the micro-increment of node active power, and U is the DC port voltage.

4. The state determination method according to claim 3, characterized in that: The method of judging the power bifurcation characteristics and static voltage stability of the AC / DC system according to the first sensitivity and the second sensitivity comprises the following steps: When J dc When >0, it means that when the DC current is increased, the DC transmission power increases accordingly, and it is determined that the system has not lost power controllability; When J dc When <0, it means that when the DC current is increased, the DC transmission power decreases instead, and the system reaches the power bifurcation point, and it is determined that the power controllability is lost; When J s <0, it means that when the AC voltage decreases, the DC feed-in reactive power increases, and the static voltage is determined to be stable; When J s When >0, it means that when the AC voltage decreases, the DC input reactive power also decreases, and the static voltage is determined to be unstable.

5. A state judgment device for a multi-feed system, applied to electronic equipment, characterized in that: The state judgment device comprises: A matrix building module is configured to establish a fourth-order Jacobian matrix based on a per-unit quasi-steady-state equation group of a single-feed system, with a cut-off angle, a DC current, an AC voltage and a micro-increment of a power angle of the single-feed system as independent variables, and with a DC voltage, a DC transmission power, a node reactive power and a node active power of the single-feed system as dependent variables; A matrix transformation module is configured to perform matrix transformation on the fourth-order Jacobian matrix to obtain power bifurcation Jacobian matrices and static voltage stability Jacobian matrices of four different control modes; A first calculation module is configured to calculate according to the elements of the power bifurcation Jacobian matrix to obtain a first sensitivity of the DC transmission power to the DC current in the single-feed system; A second calculation module is configured to calculate according to the elements of the static voltage stability Jacobian matrix to obtain a second sensitivity of the reactive power generated by the DC system in the single-feed system to the AC voltage; A judgment execution module, configured to judge the power bifurcation characteristics and static voltage stability of the AC / DC system according to the first sensitivity and the second sensitivity; The per-unit quasi-steady-state equations are: P d =U d AND d P=P d -UEsin(θ) / Z Q=Q d +ωB c U 2 -(U 2 -UEcos(θ)) / Z Among them, P d , U d ,I d , γ and X are the active power, voltage, current, turn-off angle and commutation reactance on the DC side respectively. The AC power grid is represented by a voltage source E and an impedance Z in series after the Thevenin equivalent. k is the ratio of the DC side voltage reference value to the AC measured voltage reference value. K is the transformer ratio. U is the DC port voltage.

6. The state determination device according to claim 5, characterized in that: The fourth-order Jacobian matrix is ​​as follows: Among them, Δγ is the micro-increment of the shutdown angle, ΔId is the micro-increment of the DC current, ΔU is the micro-increment of the AC voltage, Δθ is the micro-increment of the power angle, ΔUd is the micro-increment of the DC voltage, ΔPd is the micro-increment of the DC transmission power, ΔP is the micro-increment of the node reactive power, ΔQ is the micro-increment of the node active power, and U is the DC port voltage.

7. The state determination device according to claim 5, characterized in that: The relationship between the micro-increment of the DC transmission power and the micro-increment of the DC current is: ΔP d =J dc ΔI d Among them, J dc is the first sensitivity, The relationship between the micro-increment of the node reactive power and the micro-increment of the AC voltage is: ΔQ=J S ΔU / U Among them, J s is the second sensitivity, Where ΔId is the micro-increment of DC current, ΔU is the micro-increment of AC voltage, ΔPd is the micro-increment of DC transmission power, ΔQ is the micro-increment of node active power, and U is the DC port voltage.

8. The state determination device according to claim 7, characterized in that: The judgment execution module includes: The first determination unit is used when J dc >0, it is determined that the multi-feed system has not lost power controllability. dc <0, it is determined that the multi-feed system loses power controllability; The second determination unit is used when J s <0, the static voltage of the multi-feed system is determined to be stable. s >0, it is determined that the static voltage of the multi-feed system is unstable.

9. An electronic device, characterized in that: The method comprises at least one processor and a memory connected to the processor, wherein: The memory is used to store computer programs or instructions; The processor is used to execute the computer program or instruction so that the electronic device implements the state judgment method of the multi-feed system according to any one of claims 1 to 4.

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