Short-circuit calculation method, system, medium and equipment for converter-type power supply power system

Abstract

The present invention discloses a method, system, medium and equipment for calculating the short-circuit of a power system containing a converter type power supply. The method takes the control mode switching of the converter type power supply under system fault into consideration in the short-circuit calculation, and proposes an alternating iterative method based on the obtained constraint conditions and network fault equations. The method can quickly solve the short-circuit calculation problem of the power system containing the converter type power supply with high accuracy, and can also summarize the factors affecting the output short-circuit current of the converter type power supply, providing a reference for the setting and design of the controller.

Description

Technical Field

[0001] The present invention belongs to the field of electric power technology, and in particular relates to a short-circuit calculation method, system, medium and equipment for a converter-type power supply power system. Background Art

[0002] With the large-scale application of renewable energy and the rapid development of converter technology, converter interfaced generations (CIGs) have gradually become one of the mainstream power generation forms in modern power systems. Compared with traditional synchronous generators (SGs), renewable energy generation technology fed by voltage source converters (VSCs) can achieve rapid decoupling of active and reactive power, providing important support for stable system operation. At the same time, the short-circuit characteristics of renewable energy generators are significantly different from those of traditional synchronous generators due to the influence of control. Therefore, a detailed analysis of the impact and contribution of converter interfaced generations on system short-circuit current is essential.

[0003] Existing literature primarily focuses on the dynamic characteristics of short-circuit current injected into the fault point by converter-type power supplies during grid faults, short-circuit current calculation methods, and measures to limit short-circuit current levels. For example, when the converter filter inductance or overcurrent protection limiter are large, or when reactive power support requirements are high during fault ride-through, the converter output current may not track the command value during the fault ride-through period. However, few studies have considered the impact of converter control mode switching on system short-circuit current levels during system fault transients. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the deficiencies in the above-mentioned prior art and provide a method, system, medium and equipment for calculating short-circuit of a converter-type power supply power system, so as to solve the technical problems of relay protection setting of the new energy power system and the inability to select circuit breakers and protection equipment of the new energy power system.

[0005] The present invention adopts the following technical solutions:

[0006] A method for calculating short circuit of a converter type power supply power system comprises the following steps:

[0007] S1. Establish a control model for a converter-type power supply, and obtain the constraints of the converter-type power supply under control modes in which the converter-type power supply does not provide reactive power support, the converter-type power supply provides reactive power support for the system without triggering current limiting control, the q-axis component of the converter-type power supply output current follows a reference value, the d-axis component of the converter-type power supply output current is less than a reference value, and the converter-type power supply provides reactive power support for the system with a maximum allowable current;

[0008] S2. Establish a fault network model of the power system containing converter-type power supply;

[0009] S3. Based on the fault network model obtained in step S2 and the constraints of the converter type power supply under different control modes obtained in step S1, short circuit calculation applicable to the power system containing the converter type power supply is implemented.

[0010] Specifically, in step S1, the constraints of the converter type power supply are as follows:

[0011] The converter type power supply does not provide reactive power support control mode U1:

[0012]

[0013] The converter type power supply provides reactive power support control mode U2 for the system without triggering the current limit control:

[0014]

[0015] The q-axis component of the converter-type power supply output current follows the reference value, and the d-axis component of the converter-type power supply output current is less than the reference value. Control mode U3:

[0016]

[0017] The converter type power supply provides reactive power support for the system at the maximum allowable current in control mode U4:

[0018]

[0019] Among them, V p 、V t 、V n as well as They are the system PCC point voltage, the starting voltage of low voltage ride-through control, the system rated voltage, and the critical voltage of the switching point between mode 3 and mode 4, I c 、 and I n They represent the short-circuit current output by the converter type power supply, the maximum short-circuit current allowed by the converter type power supply, and the rated current of the system. Indicates the reference value of the active power output of the converter type power supply. is the output current phase angle of the converter type power supply provided by the low voltage ride through control, kv represents the reactive power support factor of the low voltage ride through control, P c It is the active power actually output by the converter type power supply.

[0020] Specifically, in step S2, the fault network model of the power system including the converter type power supply is specifically:

[0021]

[0022] in, as well as They represent the synchronous motor node voltage phasor column vector, the system PCC point voltage phasor column vector and the load node voltage phasor column vector respectively. and are the output current phasor column vector of the converter type power supply and the transient current phasor column vector of the synchronous motor node, Z s and K s are the equivalent synchronous impedance matrix and the equivalent synchronous coefficient matrix, Y p and K p They represent the PCC point equivalent admittance matrix and PCC point equivalent coefficient matrix, Y ab Represents the corresponding block matrix in the system admittance matrix, a, b = 1, 2, 3.

[0023] Furthermore, the definitions of the parameters in the fault network equation are as follows:

[0024]

[0025] Specifically, in step S3, the short-circuit calculation results of the power system including the converter type power supply are as follows:

[0026]

[0027] in, is the voltage vector at PCC point, V p ∠θ c is the output short-circuit current vector of the converter type power supply, Y p and K p are the PCC point equivalent admittance matrix and PCC point equivalent coefficient matrix respectively, is the column vector of the synchronous motor node transient current phasor.

[0028] Furthermore, the PCC point current vector for:

[0029]

[0030] Among them, I ckis the short-circuit current output by the kth converter type power supply, θ c represents the short-circuit current phase angle vector provided by the phase-locked loop control, θ ck is the short-circuit current phase angle provided by the phase-locked loop control of the k-th converter type power supply, is the short-circuit current phase angle provided by the low voltage ride-through control of the k-th converter type power supply, the subscript k represents the total number of converter type power supplies included in the power system, j represents the imaginary unit, and T is the matrix transpose symbol.

[0031] Furthermore, the inverter-type power supply output short-circuit voltage vector V p ∠θ c for:

[0032]

[0033] Among them, θ c represents the short-circuit current phase angle vector provided by the phase-locked loop control, c represents the PCC point voltage phase angle vector provided by the phase-locked loop control, V pk is the voltage amplitude at the PCC point of the k-th converter type power supply, is the exponential expression of the voltage phase angle at the PCC point of the kth converter-type power source, where the subscript k represents the total number of converter-type power sources in the power system, j represents the imaginary unit, and T is the matrix transpose symbol.

[0034] In a second aspect, an embodiment of the present invention provides a short-circuit calculation system for a converter-type power supply power system, comprising:

[0035] A constraint module establishes a control model of the converter-type power supply, and obtains the constraints of the converter-type power supply under the control modes of: the converter-type power supply does not provide reactive power support; the converter-type power supply provides reactive power support for the system without triggering current limiting control; the q-axis component of the converter-type power supply output current follows the reference value; the d-axis component of the converter-type power supply output current is less than the reference value; and the converter-type power supply provides reactive power support for the system with the maximum allowable current;

[0036] Modeling module, which establishes a fault network model of the power system containing converter-type power supply;

[0037] The calculation module implements short-circuit calculation for power systems containing converter-type power supplies based on the fault network model obtained by the modeling module and the converter-type power supply constraints under different control modes obtained by the constraint module.

[0038] In a third aspect, a computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above-mentioned method for calculating short circuit of a converter-type power supply power system when executing the computer program.

[0039] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, comprising a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for calculating a short circuit of a converter-type power supply power system.

[0040] Compared with the prior art, the present invention has at least the following beneficial effects:

[0041] The present invention provides a method for calculating the short-circuit of a power system containing a converter type power supply. The method takes the control mode switching of the converter type power supply under system fault into consideration when calculating the short-circuit. An alternating iterative algorithm is proposed based on the obtained constraints and network fault equations. The method can quickly solve the short-circuit calculation problem of the power system containing the converter type power supply with high accuracy. The method can also summarize the factors affecting the output short-circuit current of the converter type power supply, providing a reference for the setting and design of the controller. Please refer to it.

[0042] Furthermore, based on the commonly used control equations of converter-type power supplies, the constraints of converter-type power supplies under different control modes are derived.

[0043] Furthermore, based on the fault network model of traditional power systems, a fault network model for power systems containing converter-type power sources was derived. Based on this network model, an alternating iterative algorithm was proposed to quickly and accurately calculate the short-circuit problem of power systems containing converter-type power sources, and the factors affecting the short-circuit current level of converter-type power sources were summarized.

[0044] Furthermore, based on the system parameters of the power system containing converter-type power supplies, the parameters in the fault network equation are derived to quickly solve the short-circuit calculation results.

[0045] Furthermore, based on the derived fault network equation, the short-circuit current calculation results of the converter-type power supply power system are obtained, namely the converter-type power supply output short-circuit current and PCC point voltage, which provide a basis for the relay protection setting of the new energy power system and the selection of circuit breakers and protection equipment.

[0046] Furthermore, based on the proposed alternating iterative algorithm, the amplitude and phase angle of the converter-type power supply output short-circuit current can be obtained, and the relay protection setting of the new energy power system can be carried out based on the obtained results.

[0047] Furthermore, based on the proposed alternating iterative algorithm, the voltage amplitude and phase angle at the PCC point of the converter-type power supply can be obtained, and the circuit breakers and protection equipment of the new energy power system can be selected based on the obtained results.

[0048] It can be understood that the beneficial effects of the second to third aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0049] In summary, the present invention summarizes the key factors affecting the short-circuit current level of the converter-type power supply. Based on the obtained short-circuit calculation results of the converter-type power supply power system, it can quickly and accurately calculate the short-circuit problems of the power system containing the converter-type power supply, which lays a theoretical foundation for the rapid setting of relay protection of the new energy power system and the selection of circuit breakers and protection equipment for the new energy power system.

[0050] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 Flowchart of the present invention;

[0052] Figure 2 This is a schematic diagram of the equivalent circuit of a converter type power supply;

[0053] Figure 3 This is a schematic diagram of the equivalent network of a power system containing a converter type power supply;

[0054] Figure 4 is a flow chart of an alternating iterative algorithm for short-circuit calculation;

[0055] Figure 5 This is the node voltage error analysis diagram of the system under different transition resistances;

[0056] Figure 6 This is the node voltage error analysis diagram of the system under different fault locations. DETAILED DESCRIPTION

[0057] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0058] In the description of the present invention, it is to be understood that the terms “include” and “comprise” indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0059] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0060] It should be further understood that the term "and / or" as used in the present specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items. For example, A and / or B may represent: A alone, A and B simultaneously, or B alone. In addition, the character " / " herein generally indicates that the associated items are in an "or" relationship.

[0061] It should be understood that although the terms "first," "second," and "third" may be used to describe preset ranges in embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are merely used to distinguish one preset range from another. For example, without departing from the scope of embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0062] The word "if," as used herein, may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0063] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0064] The present invention provides a method for calculating short-circuit current in a power system with a converter-type power supply. First, a control model for the converter-type power supply is established, and the constraints of the converter-type power supply under different control modes are determined. On this basis, a fault network model for the power system containing the converter-type power supply is established, and equations that can quickly calculate the system fault power flow are further derived. Ultimately, an alternating iterative algorithm for calculating system short-circuit current is obtained. This method provides an alternating iterative algorithm that can quickly solve the system fault power flow with high accuracy. The algorithm results show that the short-circuit current that the converter-type power supply can provide is closely related to factors such as the converter control mode, fault location, and transition resistance.

[0065] See also Figure 1The present invention provides a method for calculating short circuits in a converter-type power system. Based on a fault network model of a converter-type power system and combined with actual system parameters, the method can quickly and accurately calculate the short circuit problem of the system. The specific steps are as follows:

[0066] S1. Establish a control model of the converter type power supply and obtain the constraints of the converter type power supply under different control modes;

[0067] The constraints of the converter-type power supply under different control modes are described by the following equations:

[0068]

[0069]

[0070]

[0071]

[0072] Among them, V p 、V t 、V n as well as They are the system PCC point voltage, the starting voltage of low voltage ride-through control, the system rated voltage, and the critical voltage of the switching point between mode 3 and mode 4; I c 、 and I n Respectively represent the short-circuit current output by the converter type power supply, the maximum short-circuit current allowed by the converter type power supply, and the rated current of the system; Indicates the reference value of the active power output of the converter type power supply; k is the output current phase angle of the converter type power supply provided by the low voltage ride-through control; v Represents the reactive power support factor of low voltage ride-through control; U1, U2, U3 and U4 correspond to the four control modes of the converter type power supply.

[0073] See also Figure 2 , Figure 2 Schematic diagram of equivalent circuit of inverter type power supply;

[0074] The commonly used control equations for converter-type power supplies (excluding the inner and outer loops) are:

[0075] Low voltage ride-through control:

[0076]

[0077] Current limit control:

[0078]

[0079] in, and They represent the d-axis component and q-axis component of the output current of the converter type power supply respectively; and They represent the d-axis component and q-axis component of the output current reference value of the converter type power supply respectively; V is the maximum short-circuit current allowed by the converter type power supply; p 、V t and V n They represent the system PCC point voltage, the starting voltage of low voltage ride-through control and the system rated voltage respectively; k v Indicates the reactive power support factor for low voltage ride through control.

[0080] Based on equations (1) and (2), it can be concluded that the converter-type power supply with low voltage fault ride-through capability can switch to one of the following four control modes during a power system fault.

[0081] Mode 1 (U1): When the PCC voltage is still higher than the LVRT start voltage, the converter does not provide reactive power support. Instead, the converter's active power is regulated to the set reference value.

[0082]

[0083] Among them, P c and Respectively represent the active power output by the converter type power supply and its reference value; It is the output current phase angle of the converter type power supply provided by the low voltage ride through control.

[0084] Mode 2 (U2): When the voltage at the PCC point is lower than the starting voltage of the low voltage ride-through control, the converter-type power supply can provide reactive power support for the system without triggering the current limit control.

[0085]

[0086] Mode three (U3): When the PCC point voltage is lower than the starting voltage of the low voltage ride-through control and the converter current limit control is started, the q-axis component of the converter-type power supply output current can follow its reference value, while the d-axis component of the converter-type power supply output current is less than the reference value due to the effect of the current limit control.

[0087]

[0088] Mode 4 (U4): When the voltage at the PCC point is lower than the critical voltage, the converter-type power supply can only provide reactive power support for the system with its maximum allowable current.

[0089]

[0090] in, It is the critical voltage of the switching point between mode 3 U3 and mode 4 U4.

[0091] At this time, the inverter-type power supply needs to meet the following constraints:

[0092]

[0093] S2. Establish a fault network model of the power system containing converter-type power supply;

[0094] See also Figure 3 , Figure 3 The equivalent network diagram of a power system with converter-type power sources is shown below. Based on the fault network form of a traditional power system, a fault network model of a power system with converter-type power sources is written.

[0095]

[0096] in, and Represent the voltage phasor column vector and current phasor column vector of all nodes in the system respectively; as well as They represent the synchronous motor node voltage phasor column vector, the system PCC point voltage phasor column vector, and the load node voltage phasor column vector respectively; and They represent the synchronous motor node current phasor column vector and the converter type power supply output current phasor column vector respectively; Y f is the admittance matrix of the fault network equation.

[0097] In practical short-circuit calculations, the dynamics of synchronous machines are described by the following equations:

[0098]

[0099] in, represents the subtransient electromotive force of the synchronous generator; represents the subtransient current of the synchronous generator; x″ represents the subtransient reactance of the synchronous generator; y g represents the equivalent admittance of the synchronous generator; and They represent the output voltage and output current of the synchronous generator port respectively.

[0100] Substituting formula (9) into formula (8), we can obtain the optimized fault network equation:

[0101]

[0102] in, represents the column vector of the sub-transient current phasor of the synchronous motor node; Y ab (a, b=1, 2, 3) represents the corresponding block matrix in the system admittance matrix.

[0103] Based on formula (10), the fault network model of the power system containing converter type power supply is described by the following formula:

[0104]

[0105] in, as well as They represent the synchronous motor node voltage phasor column vector, the system PCC point voltage phasor column vector, and the load node voltage phasor column vector respectively; and are the output current phasor column vector of the converter type power supply and the transient current phasor column vector of the synchronous motor node respectively; Z s and K s are the equivalent synchronous impedance matrix and the equivalent synchronous coefficient matrix respectively; Y p and K p They represent the equivalent admittance matrix and the equivalent coefficient matrix of the PCC point respectively; Y ab (a, b=1, 2, 3) represents the corresponding block matrix in the system admittance matrix.

[0106] The specific definitions of the parameters in the fault network equation are as follows:

[0107]

[0108] Among them, Y ab (a, b=1, 2, 3) represents the corresponding block matrix in the system admittance matrix.

[0109] S3. Based on the fault network model obtained in step S2 and the constraints of the converter type power supply under different control modes obtained in step S1, short circuit calculation applicable to the power system containing the converter type power supply is implemented.

[0110] According to formula (11), the short-circuit calculation results of the power system containing converter type power supply are as follows:

[0111]

[0112] The specific definitions of the PCC point voltage vector and the converter-type power supply output short-circuit current vector are as follows:

[0113]

[0114] Where c represents the voltage phase angle vector at the PCC point provided by the phase-locked loop control; the subscript k represents the total number of converter-type power supplies included in the power system; the subscript i represents the i-th converter-type power supply; and j represents an imaginary unit.

[0115] Based on equations (12), (13) and the equation constraints of the converter-type power supply under different control modes in step S1, the short-circuit calculation problem of the studied system is quickly solved; through the inequality constraints of the converter-type power supply under different control modes, it can be judged whether the obtained result is correct.

[0116] See also Figure 4 , the specific process of the alternating iterative algorithm for short-circuit calculation is:

[0117] enter k v , I n , V t , forming the admittance matrix Y f , and calculate Z p (This symbol is not found), Z s , K p , K s , set U1=U2=U3=φ,U4=U, combine equations (23) and (24) to calculate V p , I c ,θ c , Using the formula P ci =V pi I ci Calculate the active power output of each CIG:

[0118] When V pi ≥V ti When , the CIG belongs to control mode 1, so its node number i is stored in the set middle;

[0119] When V pi <V ti and When , the CIG belongs to control mode 4, so its node number i is stored in the set middle;

[0120] When V pi <V ti and At this time, it is necessary to compare the actual output power of each CIG with its reference output power value to determine its control mode;

[0121] when When , the CIG belongs to control mode 3, so its node number i is stored in the set middle;

[0122] If the power does not satisfy the above inequality, the CIG belongs to control mode 2, so its node number is stored in the set Then, determine whether the elements in the set before and after a calculation are consistent; if they are consistent, calculate V p 、V l , and output V p 、V g 、V l If the result is inconsistent, recalculate V p , I c ,θ c , The value of and repeat the above judgment process until the elements in the set before calculation are the same as the elements in the set after calculation.

[0123] In another embodiment of the present invention, a converter type power supply power system short circuit calculation system is provided, which can be used to implement the above converter type power supply power system short circuit calculation method. Specifically, the converter type power supply power system short circuit calculation system includes a constraint module, a modeling module and a calculation module.

[0124] Among them, the constraint module establishes a control model of the converter-type power supply, obtains the converter-type power supply constraints under the control mode in which the converter-type power supply does not provide reactive power support, the converter-type power supply provides reactive power support for the system without triggering current limit control, the q-axis component of the converter-type power supply output current follows the reference value, the d-axis component of the converter-type power supply output current is less than the reference value, and the converter-type power supply provides reactive power support for the system with the maximum allowable current;

[0125] Modeling module, which establishes a fault network model of the power system containing converter-type power supply;

[0126] The calculation module implements short-circuit calculation for power systems containing converter-type power supplies based on the fault network model obtained by the modeling module and the converter-type power supply constraints under different control modes obtained by the constraint module.

[0127] In another embodiment of the present invention, a terminal device is provided, which includes a processor and a memory, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions to implement the corresponding method flow or corresponding function; the processor described in the embodiment of the present invention can be used for the operation of the converter-type power supply power system short-circuit calculation method, including:

[0128] A control model of a converter-type power supply is established to obtain the constraints of the converter-type power supply under the control mode in which the converter-type power supply does not provide reactive power support, the converter-type power supply provides reactive power support for the system without triggering current limiting control, the q-axis component of the converter-type power supply output current follows the reference value, the d-axis component of the converter-type power supply output current is less than the reference value, and the converter-type power supply provides reactive power support for the system with the maximum allowable current; a fault network model of a power system containing a converter-type power supply is established; based on the fault network model and the constraints of the converter-type power supply under different control modes, short-circuit calculation suitable for a power system containing a converter-type power supply is realized.

[0129] In another embodiment of the present invention, the present invention further provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a terminal device for storing programs and data. It can be understood that the computer-readable storage medium here can include both the built-in storage medium in the terminal device and, of course, the extended storage medium supported by the terminal device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space. These instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory (Non-Volatile Memory), such as at least one disk memory.

[0130] The processor may load and execute one or more instructions stored in a computer-readable storage medium to implement the corresponding steps of the method for calculating a short circuit of a converter-type power supply system in the above embodiment. The processor may load and execute the following steps:

[0131] A control model of a converter-type power supply is established to obtain the constraints of the converter-type power supply under the control mode in which the converter-type power supply does not provide reactive power support, the converter-type power supply provides reactive power support for the system without triggering current limiting control, the q-axis component of the converter-type power supply output current follows the reference value, the d-axis component of the converter-type power supply output current is less than the reference value, and the converter-type power supply provides reactive power support for the system with the maximum allowable current; a fault network model of a power system containing a converter-type power supply is established; based on the fault network model and the constraints of the converter-type power supply under different control modes, short-circuit calculation suitable for a power system containing a converter-type power supply is realized.

[0132] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0133] Please refer to Table 1, which shows the relevant parameters of the test system.

[0134] Table 1

[0135]

[0136] Please refer to Table 2. From the results in Table 2, we can obtain the calculation results of the PCC point voltage of the converter-type power supply in four different control modes. These calculation and simulation results show the correctness of the means proposed in the present invention for distinguishing the control mode of the converter-type power supply when the system fails. In addition, by comparing the simulation results and the algorithm calculation results, it is not difficult to see that the final result obtained by the proposed algorithm is very similar to the result of numerical simulation through the simulation platform, and the error does not exceed 1.5%. This effectively illustrates the effectiveness and accuracy of the present invention, which can well perform parameter setting of relay protection of new energy power systems, and lays a theoretical foundation for the selection of circuit breakers and protection equipment for new energy power systems.

[0137] Table 2 PCC point voltage calculation results of each converter type power supply

[0138]

[0139] See also Figure 5 , Figure 5 The following diagram shows the system's node voltage error analysis for different transition resistances. It can be seen that the proposed algorithm exhibits slightly different errors under different transition resistances. A larger transition resistance results in a smaller node voltage amplitude error, but a larger node voltage phase angle error. Furthermore, since the true value is very close to zero, the phase angle error is generally larger than the amplitude error, but never exceeds 4%. This demonstrates the high accuracy of the proposed algorithm.

[0140] See also Figure 6 , Figure 6 Figure 2 shows the system node voltage error analysis for different fault locations. It can be seen that the accuracy of the proposed algorithm is not significantly affected by the different fault locations. The error between the two approaches is primarily due to their inherent characteristics and does not exceed 2%. This verifies the high accuracy of the proposed method.

[0141] In summary, the present invention provides a method, system, medium and equipment for calculating the short-circuit of a converter-type power supply power system, which takes the switching of the converter-type power supply control mode under system fault into consideration in the short-circuit calculation, and proposes an alternating iterative method based on the obtained constraints and network fault equations. While being able to quickly solve the short-circuit calculation problem of the power system containing the converter-type power supply with high accuracy, it can also summarize the factors affecting the output short-circuit current of the converter-type power supply, providing a reference for the setting and design of the controller.

[0142] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0143] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes 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 device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. 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.

[0144] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0145] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0146] The above content is only for explaining the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for calculating short circuit of a converter type power system, characterized in that: The following steps are involved: S1. Establish a control model for the converter type power supply, and obtain the following conditions: the converter type power supply does not provide reactive power support, the converter type power supply provides reactive power support for the system without triggering current limit control, and the converter type power supply output current. q The axis component follows the reference value, the output current of the inverter type power supply d The axis component is less than the reference value and the converter type power supply provides reactive power support control mode for the system with the maximum allowable current; S2. Establish a fault network model of the power system containing a converter type power supply. The fault network model of the power system containing a converter type power supply is specifically as follows: in, 、 as well as They represent the synchronous motor node voltage phasor column vector, the system PCC point voltage phasor column vector and the load node voltage phasor column vector respectively. and are the output current phasor column vector of the converter type power supply and the sub-transient current phasor column vector of the synchronous motor node, Z s and K s are the equivalent synchronous impedance matrix and the equivalent synchronous coefficient matrix respectively, Y p and K p They represent the PCC point equivalent admittance matrix and PCC point equivalent coefficient matrix respectively, Y ab represents the corresponding block matrix in the system admittance matrix, a , b= 1, 2, 3; the details are as follows: ； S3. Based on the fault network model obtained in step S2 and the constraints of the converter-type power supply under different control modes obtained in step S1, a short-circuit calculation applicable to the power system containing the converter-type power supply is performed; The short-circuit calculation results of the power system containing converter-type power supply are as follows: in, is the current vector at the PCC point, is the output short-circuit current vector of the converter type power supply, Y p and K p are the PCC point equivalent admittance matrix and PCC point equivalent coefficient matrix respectively; PCC point current vector for: in, For the k The short-circuit current output by the inverter type power supply, represents the short-circuit current phase angle vector provided by the phase-locked loop control, For the k The short-circuit current phase angle of the inverter type power supply is provided by the phase-locked loop control, For the k The short-circuit current phase angle provided by the low voltage ride-through control of the converter type power supply, subscript k Indicates the total number of converter-type power supplies included in the power system. j represents the imaginary unit, is the matrix transpose symbol; Output short-circuit voltage vector of converter type power supply for: in, represents the short-circuit current phase angle vector provided by the phase-locked loop control, Represents the PCC point voltage phase angle vector provided by the phase-locked loop control, For the k The voltage amplitude at the PCC point of the converter type power supply is For the k The exponential expression of the voltage phase angle at the PCC point of a converter-type power supply, subscript k Indicates the total number of converter-type power supplies included in the power system. represents the imaginary unit, is the matrix transpose symbol.

2. The method for calculating short circuit of a converter type power supply power system according to claim 1, characterized in that: In step S1, the constraints of the converter type power supply are as follows: The inverter type power supply does not provide reactive power support control mode : The converter type power supply provides reactive power support control mode for the system without triggering current limit control : Output current of inverter type power supply q The axis component follows the reference value, the output current of the inverter type power supply d Axis component is less than reference value control mode : The converter type power supply provides reactive power support control mode for the system with the maximum allowable current : in, 、 、 as well as They are the system PCC point voltage, the starting voltage of low voltage ride-through control, the system rated voltage, and the critical voltage of the switching point between mode three and mode four. 、 as well as They represent the short-circuit current output by the converter type power supply, the maximum short-circuit current allowed by the converter type power supply, and the rated current of the system. Indicates the reference value of the active power output of the converter type power supply. is the output current phase angle of the converter type power supply provided by the low voltage ride through control, Indicates the reactive power support coefficient of low voltage ride through control, It is the active power actually output by the converter type power supply.

3. A short-circuit calculation system for a converter type power supply power system, characterized in that: include: Constraint module, establish the control model of the converter type power supply, obtain the converter type power supply does not provide reactive power support, the converter type power supply provides reactive power support for the system without triggering the current limit control, and the converter type power supply output current q The axis component follows the reference value, the output current of the inverter type power supply d The axis component is less than the reference value and the converter type power supply provides reactive power support control mode for the system with the maximum allowable current; The modeling module establishes a fault network model of the power system containing a converter type power supply. The fault network model of the power system containing a converter type power supply is specifically as follows: in, 、 as well as They represent the synchronous motor node voltage phasor column vector, the system PCC point voltage phasor column vector and the load node voltage phasor column vector respectively. and are the output current phasor column vector of the converter type power supply and the sub-transient current phasor column vector of the synchronous motor node, Z s and K s are the equivalent synchronous impedance matrix and the equivalent synchronous coefficient matrix respectively, Y p and K p They represent the PCC point equivalent admittance matrix and PCC point equivalent coefficient matrix respectively, Y ab represents the corresponding block matrix in the system admittance matrix, a , b= 1, 2, 3; The definitions of the parameters in the fault network equation are as follows: ； The calculation module implements short-circuit calculation for power systems containing converter-type power supplies based on the fault network model obtained by the modeling module and the converter-type power supply constraints under different control modes obtained by the constraint module; The short-circuit calculation results of the power system containing converter-type power supply are as follows: in, is the current vector at the PCC point, is the output short-circuit current vector of the converter type power supply, Y p and K p are the PCC point equivalent admittance matrix and PCC point equivalent coefficient matrix respectively, is the column vector of the sub-transient current phasor of the synchronous motor node; PCC point current vector for: in, For the k The short-circuit current output by the inverter type power supply, represents the short-circuit current phase angle vector provided by the phase-locked loop control, For the k The short-circuit current phase angle of the inverter type power supply is provided by the phase-locked loop control, For the k The short-circuit current phase angle provided by the low voltage ride-through control of the converter type power supply, subscript k Indicates the total number of converter-type power supplies included in the power system. j represents the imaginary unit, is the matrix transpose symbol; Output short-circuit voltage vector of converter type power supply for: in, represents the short-circuit current phase angle vector provided by the phase-locked loop control, Represents the PCC point voltage phase angle vector provided by the phase-locked loop control, For the k The voltage amplitude at the PCC point of the converter type power supply is For the k The exponential expression of the voltage phase angle at the PCC point of a converter-type power supply, subscript k Indicates the total number of converter-type power supplies included in the power system. represents the imaginary unit, is the matrix transpose symbol.

4. A computer-readable storage medium storing one or more programs, characterized in that: The one or more programs include instructions that, when executed by a computing device, cause the computing device to perform any one of the methods according to claim 1 or 2.

5. A computing device, characterized in that include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs include instructions for executing any of the methods according to claim 1 or 2.

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