Method and system for calculating voltage power sensitivity of cross-voltage-class AC / DC power distribution network

Abstract

The invention discloses a method and a system for calculating voltage power sensitivity of a cross-voltage-class AC / DC power distribution network, and relates to the technical field of power sensitivity analysis of a power system, and the method comprises the steps: building a loss model of a transformer based on the primary side current and voltage of the transformer, and neglecting the conditions of excitation current and iron core loss; establishing a loss model of the VSC equipment based on the current of the VSC AC side, the active power and reactive power exchanged at the AC side and the loss coefficient; obtaining a power transmission relation based on the loss models of the transformer and the VSC equipment; based on the power transmission relation, a voltage drop equation is combined, and a voltage power sensitivity calculation formula of the cross-voltage-level alternating current and direct current power distribution network is obtained through derivation; sensitivity calculation between medium-low voltage and alternating-current and direct-current nodes is achieved, universality is achieved, and a theoretical basis can be provided for planning and operation control of a medium-low voltage alternating-current and direct-current power distribution network.

Description

Technical Field

[0001] The present invention relates to the technical field of power system voltage and power sensitivity analysis, and in particular to a method and system for calculating voltage and power sensitivity of a cross-voltage level AC and DC distribution network. Background Art

[0002] At present, with the access of a high proportion of renewable energy and the increase of new power-consuming equipment, medium and low voltage coordinated AC and DC distribution networks will become the development trend of distribution networks. The use of AC and DC distribution networks can improve the carrying capacity of new sources and loads. However, in medium and low voltage AC and DC distribution networks, power transmission equipment will also affect the voltage. The above research does not consider the model of power transmission equipment and is not suitable for medium and low voltage AC and DC distribution networks containing transformers, voltage source converters (VSC) and other equipment. Therefore, in order to characterize the sensitivity between nodes in medium and low voltage AC and DC distribution networks, the power transmission characteristics of transformers and converters should be considered, and the sensitivity calculation method applicable to cross-voltage AC and DC distribution networks should be studied.

[0003] Voltage sensitivity is an indicator used in power systems to measure the sensitivity of the voltage of a node in the system to the power changes of other nodes in the system. Voltage sensitivity indicators are used in distribution network planning, operation control, etc., and can establish linear system models to reduce control complexity. At present, the calculation of voltage sensitivity is mainly derived from the power flow calculation method. There are two types of sensitivity calculation methods: the sensitivity calculation method based on the Newton-Ray power flow algorithm and the sensitivity calculation method based on forward and backward substitution. The sensitivity calculation method based on the Newton-Ray power flow algorithm cannot obtain the voltage-power sensitivity expression analytically. It can only obtain the converged power flow calculation results through iterative calculation, and then use the Jacobian matrix to calculate to obtain the voltage-power sensitivity. It cannot intuitively reveal the relationship between voltage sensitivity and key information such as line parameters and node locations; the sensitivity calculation method based on forward and backward substitution can obtain the analytical expression of voltage sensitivity, which can intuitively explain the correlation between voltage sensitivity and line parameters and network topology. This method is simple to calculate and does not require any iteration. As long as there are relevant parameters, it can be calculated. However, this method ignores the network loss and belongs to the approximate calculation, and the calculated voltage sensitivity value is low. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is: how to accurately calculate the voltage-power sensitivity across voltage levels in medium and low voltage AC and DC distribution networks, and take into account the power model of the power transmission equipment.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, an embodiment of the present invention provides a method for calculating voltage power sensitivity of an AC / DC distribution network across voltage levels, comprising:

[0008] Based on the primary current and voltage of the transformer, ignoring the conditions of excitation current and core loss, the loss model of the transformer is established;

[0009] Based on the current on the VSC AC side, the active and reactive power exchanged on the AC side, and the loss coefficient, a loss model of the VSC equipment is established;

[0010] Based on the loss model of transformer and VSC equipment, the power transfer relationship is obtained;

[0011] Based on the power transfer relationship and combined with the voltage drop equation, a calculation formula for voltage power sensitivity of AC / DC distribution networks across voltage levels is derived.

[0012] As a preferred solution for calculating voltage power sensitivity of AC / DC distribution networks across voltage levels, the following is provided:

[0013] The loss model of the transformer is established including:

[0014] Assume that the total resistance and total reactance of the transformer are R T and X T ; The three-phase active and reactive power of the transformer primary side are P MV and Q MV , the three-phase active and reactive power on the secondary side are P LV and Q LV , ignoring the excitation current and core loss, the loss model of the transformer is expressed as:

[0015]

[0016]

[0017] Among them, P T,loss , Q T,loss are the active loss and reactive loss of the transformer respectively; I1 is the current flowing through the primary side of the transformer; U MV is the transformer primary side voltage.

[0018] As a preferred solution for calculating voltage power sensitivity of AC / DC distribution networks across voltage levels, the following is provided:

[0019] The establishment of the loss model of the VSC device includes:

[0020] The converter operation loss is expressed using the generalized converter loss model as follows:

[0021]

[0022]

[0023] Among them, I c is the current flowing through the AC side of the VSC; P c , Q c are respectively the active power and reactive power exchanged by VSC on the AC side; U c is the AC side voltage of VSC; A, B, C are loss coefficients; the calculation formula of loss coefficient is as follows:

[0024]

[0025] Among them, S N is the rated capacity of VSC, U d is the VSC DC side voltage.

[0026] As a preferred solution for calculating voltage power sensitivity of AC / DC distribution networks across voltage levels, the following is provided:

[0027] The power transmission relationship obtained based on the loss model of the transformer and the VSC device includes:

[0028] The power relationship on both sides of the transformer is as follows:

[0029]

[0030] in, are the three-phase complex powers of the primary and secondary sides of the transformer respectively;

[0031] According to the power relationship on both sides of the transformer, the transformer active loss and reactive loss are simplified as follows:

[0032]

[0033] As a preferred solution for calculating voltage power sensitivity of AC / DC distribution networks across voltage levels, the following is provided:

[0034] The power transmission relationship obtained based on the loss model of the transformer and the VSC device also includes:

[0035] The exchange power relationship between AC and DC on both sides of the VSC is:

[0036] P c =P dc +P VSC,loss

[0037] Among them, P dc Inject DC side active power into VSC;

[0038] The loss model of the VSC equipment is simplified according to the exchange power relationship between AC and DC on both sides of the VSC, and the following is obtained:

[0039]

[0040] As a preferred solution for calculating voltage power sensitivity of AC / DC distribution networks across voltage levels, the following is provided:

[0041] The derived calculation formula for voltage power sensitivity of AC / DC distribution network across voltage levels includes:

[0042] According to the voltage drop equation, the voltage relationship between adjacent nodes is expressed as:

[0043]

[0044] Among them, P Line,i , Q Line,i are respectively the active power and reactive power flowing through the line between node i-1 and node i, expressed as:

[0045]

[0046] Among them, P Loss,k , Q Loss,k is the active and reactive losses on the line between node k-1 and node k;

[0047] The voltage U of any medium voltage node i i It is expressed as:

[0048]

[0049] Among them, CN 0,i is the line and node set from node 0 to node i;

[0050] To quantify the impact of active power change of node j on node i, U i Perform derivation.

[0051] As a preferred solution for calculating voltage power sensitivity of AC / DC distribution networks across voltage levels, the following is provided:

[0052] The derived calculation formula for voltage power sensitivity of AC / DC distribution network across voltage levels also includes:

[0053] Based on the simplified transformer active and reactive losses and the simplified VSC equipment loss model, the line impedance loss in the active and reactive power flowing in the line between node i-1 and node i is ignored and substituted into the derived U i , the voltage power sensitivity calculation formula of AC / DC distribution network across voltage levels is obtained, which is expressed as:

[0054]

[0055]

[0056]

[0057] Among them, S V-P,ij and S V-Q,ij are the voltage-active and reactive sensitivities of node i to node j, i.e., the voltage change of node i caused by the unit power change of node j; CN 0,i ∩CN 0,j It is the intersection of the lines and nodes on the path from node 0 to node i and from node 0 to node j.

[0058] In a second aspect, an embodiment of the present invention provides a voltage power sensitivity calculation system for a cross-voltage level AC / DC distribution network, including:

[0059] A transformer loss model building module is used to build a transformer loss model based on the transformer primary side current and voltage, ignoring the conditions of excitation current and core loss;

[0060] A VSC loss model building module, used to build a loss model of the VSC device based on the current on the VSC AC side, the active and reactive power exchanged on the AC side, and the loss coefficient;

[0061] Power transfer relationship derivation module, used to obtain the power transfer relationship based on the loss model of transformer and VSC equipment;

[0062] The sensitivity calculation module is used to derive a voltage power sensitivity calculation formula for the AC / DC distribution network across voltage levels based on the power transmission relationship and in combination with a voltage drop equation.

[0063] In a third aspect, an embodiment of the present invention provides a computing device, including:

[0064] Memory and processor;

[0065] The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the one or more programs are executed by the one or more processors, the one or more processors implement the voltage power sensitivity calculation method for the cross-voltage level AC / DC distribution network as described in any embodiment of the present invention.

[0066] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the method for calculating voltage power sensitivity of an AC / DC distribution network across voltage levels.

[0067] Beneficial effects of the invention: The invention is aimed at medium and low voltage AC and DC distribution networks, analyzes the power transmission characteristics of power transmission equipment such as distribution transformers and VSCs, and combines the node voltage drop formula to derive the voltage power sensitivity calculation formula of AC and DC distribution networks across voltage levels, thereby realizing sensitivity calculation between medium and low voltage and AC and DC nodes. It has universality and can provide a theoretical basis for the planning and operation control of medium and low voltage AC and DC distribution networks. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0069] Figure 1 It is an overall flow chart of the voltage power sensitivity calculation method of the AC / DC distribution network across voltage levels according to the first embodiment of the present invention;

[0070] Figure 2 It is a schematic diagram of distributed photovoltaic grid connection via DC lines according to the voltage power sensitivity calculation method of AC and DC distribution networks across voltage levels described in the first embodiment of the present invention;

[0071] Figure 3 It is a schematic diagram of a medium and low voltage AC and DC power distribution system in a simulation example of a method for calculating voltage and power sensitivity of an AC and DC power distribution network across voltage levels according to a second embodiment of the present invention;

[0072] Figure 4 It is a heat map of voltage-active power sensitivity of a distribution system in a simulation example of a method for calculating voltage-power sensitivity of an AC / DC distribution network across voltage levels according to a second embodiment of the present invention;

[0073] Figure 5 It is a diagram showing the relationship between node voltage and power changes of the comparison method in a simulation example of the method for calculating voltage power sensitivity of AC / DC distribution networks across voltage levels described in the second embodiment of the present invention. DETAILED DESCRIPTION

[0074] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0075] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0076] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0077] Example 1

[0078] Reference Figure 1-Figure 2 , which is the first embodiment of the present invention, and provides a method for calculating voltage power sensitivity of a cross-voltage level AC / DC distribution network, comprising:

[0079] S1: Based on the primary current and voltage of the transformer, ignoring the conditions of excitation current and core loss, the loss model of the transformer is established;

[0080] It should be noted that the schematic diagram of distributed photovoltaic grid connection via DC lines applicable to this embodiment is as follows Figure 2 As shown, is a set of network nodes, {1,2,…,a} is a set of medium voltage AC nodes, {a+1,…,b} is a set of low voltage AC nodes, and {b+1,…,n} is a set of low voltage DC nodes; node 0 is a balance node, and the balance point voltage is U0; the node number increases with the length of the line, and the number of each line segment is consistent with the number of the last node of the line segment. The voltage (amplitude) of any node i is recorded as U i ; The line impedance between node i-1 and node i is R i +jX i In this scenario, VSC is set to U dc -Q control mode: The power of the low-voltage DC node affects the medium-voltage AC node voltage through the VSC and distribution transformer.

[0081] In the embodiment of the present application, establishing a loss model of the transformer includes:

[0082] Assume that the total resistance and total reactance of the transformer are R T and X T ; The three-phase active and reactive power of the transformer primary side are P MV and Q MV , the three-phase active and reactive power on the secondary side are P LV and Q LV, ignoring the excitation current and core loss, the loss model of the transformer is expressed as:

[0083]

[0084]

[0085] Among them, P T,loss , Q T,loss are the active loss and reactive loss of the transformer respectively; I1 is the current flowing through the primary side of the transformer; U MV is the transformer primary side voltage.

[0086] Specifically, the model can be applied to a simple medium and low voltage distribution transformer scenario, where the medium voltage side is 10 kV and the low voltage side is 0.38 kV. It is known that the distribution transformer is Dyn11 type.

[0087] S2: Establish a loss model of the VSC equipment based on the current on the VSC AC side, the active and reactive power exchanged on the AC side, and the loss coefficient;

[0088] In the embodiment of the present application, establishing a loss model of the VSC device includes:

[0089] The converter operation loss is expressed using the generalized converter loss model as follows:

[0090]

[0091]

[0092] Among them, I c is the current flowing through the AC side of the VSC; P c , Q c are respectively the active power and reactive power exchanged by VSC on the AC side; U c is the AC side voltage of VSC; A, B, C are loss coefficients; the calculation formula of loss coefficient is as follows:

[0093]

[0094] Among them, S N is the rated capacity of VSC, U d is the VSC DC side voltage.

[0095] S3: Based on the loss model of transformer and VSC equipment, the power transmission relationship is obtained;

[0096] In the embodiment of the present application, based on the loss model of the transformer and the VSC device, the power transmission relationship is obtained including:

[0097] The power relationship on both sides of the transformer is as follows:

[0098]

[0099] in, are the three-phase complex powers of the primary and secondary sides of the transformer respectively;

[0100] According to the power relationship on both sides of the transformer, the transformer active loss and reactive loss are simplified as follows:

[0101]

[0102] The exchange power relationship between AC and DC on both sides of the VSC is:

[0103] P c =P dc +P VSC,loss

[0104] Among them, P dc Inject DC side active power into VSC;

[0105] The loss model of the VSC equipment is simplified according to the exchange power relationship between AC and DC on both sides of the VSC, and the following is obtained:

[0106]

[0107] S4: Based on the power transfer relationship and in combination with the voltage drop equation, a formula for calculating voltage power sensitivity of AC / DC distribution networks across voltage levels is derived.

[0108] In the embodiment of the present application, the derived calculation formula for voltage power sensitivity of AC / DC distribution network across voltage levels includes:

[0109] According to the voltage drop equation, the voltage relationship between adjacent nodes is expressed as:

[0110]

[0111] Among them, P Line,i , Q Line,i are respectively the active power and reactive power flowing through the line between node i-1 and node i, expressed as:

[0112]

[0113] Among them, P Loss,k , Q Loss,k is the active and reactive losses on the line between node k-1 and node k;

[0114] The voltage U of any medium voltage node i i It is expressed as:

[0115]

[0116] Among them, CN 0,i is the line and node set from node 0 to node i;

[0117] To quantify the impact of active power change of node j on node i, U i Perform derivation.

[0118] Specifically, if the node The active power changes, the voltage U at node i i In order to quantify the impact of the active power change of node j on node i, U i After taking the derivative:

[0119]

[0120] In the embodiment of the present application, based on the simplified transformer active loss and reactive loss and the simplified loss model of the VSC device, the line impedance loss in the active and reactive power flowing in the line between the node i-1 and the node i is ignored, and the derived U i , the voltage power sensitivity calculation formula of AC / DC distribution network across voltage levels is obtained, which is expressed as:

[0121]

[0122] Among them, S V-P,ij and S V-Q,ij are the voltage-active and reactive sensitivities of node i to node j, i.e., the voltage change of node i caused by the unit power change of node j; CN 0,i ∩CN 0,j It is the intersection of the lines and nodes on the path from node 0 to node i and from node 0 to node j.

[0123] Specifically, the ratio of line impedance loss to total transmission power is small, so it can be ignored. The expressions of active and reactive power flowing in the line between node i-1 and node i can be expanded to obtain:

[0124]

[0125] The above is a schematic scheme of the voltage power sensitivity calculation method of the AC / DC distribution network across voltage levels of this embodiment. It should be noted that the technical scheme of the voltage power sensitivity calculation system of the AC / DC distribution network across voltage levels and the technical scheme of the voltage power sensitivity calculation method of the AC / DC distribution network across voltage levels above belong to the same concept. For details not described in detail in the technical scheme of the voltage power sensitivity calculation system of the AC / DC distribution network across voltage levels in this embodiment, please refer to the description of the technical scheme of the voltage power sensitivity calculation method of the AC / DC distribution network across voltage levels above.

[0126] In this embodiment, the voltage power sensitivity calculation system of the AC / DC power distribution network across voltage levels includes:

[0127] A transformer loss model building module is used to build a transformer loss model based on the transformer primary side current and voltage, ignoring the conditions of excitation current and core loss;

[0128] A VSC loss model building module, used to build a loss model of the VSC device based on the current on the VSC AC side, the active and reactive power exchanged on the AC side, and the loss coefficient;

[0129] Power transfer relationship derivation module, used to obtain the power transfer relationship based on the loss model of transformer and VSC equipment;

[0130] The sensitivity calculation module is used to derive a voltage power sensitivity calculation formula for the AC / DC distribution network across voltage levels based on the power transmission relationship and in combination with a voltage drop equation.

[0131] This embodiment also provides a computing device, applicable to the method, including:

[0132] Memory and processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement the method proposed in the above embodiment.

[0133] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the method proposed in the above embodiment is implemented.

[0134] The storage medium proposed in this embodiment and the method proposed in the above embodiment belong to the same inventive concept. The technical details not fully described in this embodiment can be referred to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0135] Example 2

[0136] Reference Figure 3-Figure 5 , which is an embodiment of the present invention, provides a method for calculating voltage power sensitivity of AC / DC distribution networks across voltage levels. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through simulation experiments.

[0137] The proposed voltage power sensitivity calculation method of AC / DC distribution network across voltage levels is verified by using an improved IEEE33 node example. Figure 3 The voltage level of the medium voltage layer of the system is 10kV, the voltage level of the low voltage AC layer is 380V, and the voltage level of the low voltage DC layer is ±375V; nodes 8, 9, 13, 18, 21, 25, 32, and 33 are connected to the photovoltaic power station; nodes 17 and 28 are low voltage AC and DC stations, which are connected to distributed photovoltaics through DC bus confluence.

[0138] The voltage-active power sensitivity thermal diagram of the power distribution system is as follows: Figure 4 As shown in the figure, nodes 18 and 33 are located at the end of the line, with many branches between them and the balancing node 1, and the voltage drop caused by power change is greater. The sensitivity calculation results show that nodes 18 and 33 are more sensitive to the voltage of nearby nodes, which is consistent with the theoretical analysis results.

[0139] Add power fluctuation ΔP on the DC side of the low voltage DC substation under node 17 17 , the voltage fluctuation ΔU at node 14 obtained by power flow calculation is 14 As a benchmark, the voltage level sensitivity S proposed by the present invention is used. V-P,1417 With ΔP 17 Multiply and calculate the voltage fluctuation ΔU at node 14 14 'As a comparison, Figure 5 It can be seen that the calculation results of the two methods are basically consistent, which proves the effectiveness of the voltage power sensitivity calculation formula of the AC / DC distribution network across voltage levels proposed by the present invention.

[0140] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for calculating voltage power sensitivity of AC / DC distribution network across voltage levels, characterized in that: include: Based on the primary current and voltage of the transformer, ignoring the conditions of excitation current and core loss, the loss model of the transformer is established; Based on the current on the AC side of the VSC, the active and reactive power exchanged on the AC side, and the loss coefficient, a loss model of the VSC equipment is established; Based on the loss model of transformer and VSC equipment, the power transfer relationship is obtained; Based on the power transfer relationship and combined with the voltage drop equation, a calculation formula for voltage power sensitivity of AC / DC distribution networks across voltage levels is derived.

2. The method for calculating voltage power sensitivity of AC / DC distribution network across voltage levels according to claim 1, characterized in that: The loss model of the transformer is established including: Assume that the total resistance and total reactance of the transformer are R T and X T ; The three-phase active and reactive power of the transformer primary side are P MV and Q MV , the three-phase active and reactive power on the secondary side are P LV and Q LV , ignoring the excitation current and core loss, the loss model of the transformer is expressed as: Among them, P T,loss , Q T,loss are the active loss and reactive loss of the transformer respectively; I1 is the current flowing through the primary side of the transformer; U MV is the transformer primary side voltage.

3. The method for calculating voltage power sensitivity of AC / DC distribution network across voltage levels according to claim 2, characterized in that: The establishment of the loss model of the VSC equipment includes: The converter operation loss is expressed using the generalized converter loss model as follows: Among them, I c is the current flowing through the AC side of the VSC; P c , Q c are respectively the active power and reactive power exchanged by VSC on the AC side; U c is the AC side voltage of VSC; A, B, C are loss coefficients; the calculation formula of loss coefficient is as follows: Among them, S N is the rated capacity of VSC, U d is the VSC DC side voltage.

4. The method for calculating voltage power sensitivity of AC / DC distribution network across voltage levels according to claim 3, characterized in that: The power transmission relationship obtained based on the loss model of the transformer and the VSC device includes: The power relationship on both sides of the transformer is as follows: in, are the three-phase complex powers of the primary and secondary sides of the transformer respectively; According to the power relationship on both sides of the transformer, the transformer active loss and reactive loss are simplified as follows:

5. The method for calculating voltage power sensitivity of AC / DC distribution network across voltage levels according to claim 4, characterized in that: The power transmission relationship obtained based on the loss model of the transformer and the VSC device also includes: The exchange power relationship between AC and DC on both sides of the VSC is: P c =P dc +P VSC,loss Among them, P dc Inject DC side active power into VSC; The loss model of the VSC equipment is simplified according to the exchange power relationship between AC and DC on both sides of the VSC, and the following is obtained:

6. The method for calculating voltage power sensitivity of AC / DC distribution network across voltage levels according to claim 5, characterized in that: The derived calculation formula for voltage power sensitivity of AC / DC distribution network across voltage levels includes: According to the voltage drop equation, the voltage relationship between adjacent nodes is expressed as: Among them, P Line,i , Q Line,i are respectively the active power and reactive power flowing through the line between node i-1 and node i, expressed as: Among them, P Loss,k , Q Loss,k is the active and reactive losses on the line between node k-1 and node k; The voltage U of any medium voltage node i i It is expressed as: Among them, CN 0,i is the line and node set from node 0 to node i; To quantify the impact of active power change of node j on node i, U i Perform derivation.

7. The method for calculating voltage power sensitivity of AC / DC distribution network across voltage levels according to claim 6, characterized in that: The derived calculation formula for voltage power sensitivity of AC / DC distribution network across voltage levels also includes: Based on the simplified transformer active and reactive losses and the simplified VSC equipment loss model, the line impedance loss in the active and reactive power flowing in the line between node i-1 and node i is ignored and substituted into the derived U i , the voltage power sensitivity calculation formula of AC / DC distribution network across voltage levels is obtained, which is expressed as: Among them, S V-P,ij and S V-Q,ij are the voltage-active and reactive sensitivities of node i to node j, i.e., the voltage change of node i caused by the unit power change of node j; CN 0,i ∩CN 0,j It is the intersection of the lines and nodes on the path from node 0 to node i and from node 0 to node j.

8. A system using the method for calculating voltage power sensitivity of AC / DC distribution network across voltage levels as claimed in any one of claims 1 to 7, characterized in that: include: A transformer loss model building module is used to build a transformer loss model based on the transformer primary side current and voltage, ignoring the conditions of excitation current and core loss; A VSC loss model building module, used to build a loss model of the VSC device based on the current on the VSC AC side, the active and reactive power exchanged on the AC side, and the loss coefficient; The power transfer relationship derivation module is used to obtain the power transfer relationship based on the loss model of transformer and VSC equipment; The sensitivity calculation module is used to derive a voltage power sensitivity calculation formula for the AC / DC distribution network across voltage levels based on the power transmission relationship and in combination with a voltage drop equation.

9. A computing device comprising: Memory and processor; The memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions. When the computer executable instructions are executed by the processor, the steps of the method for calculating voltage power sensitivity of AC and DC distribution networks across voltage levels according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the steps of the method for calculating voltage power sensitivity of an AC / DC distribution network across voltage levels as claimed in any one of claims 1 to 7.

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