Methods for Selecting DC Main Equipment Parameters to Improve Transient Stability of Power Grid

Abstract

This invention relates to a method for selecting DC main equipment parameters to improve the transient stability of AC / DC hybrid power grids, a device for selecting DC main equipment parameters in AC / DC hybrid power grids, a computer-readable medium storing a device parameter selection program, and an electronic device. First, considering only the safety operation constraints of the DC system, the leakage reactance range of the converter transformer is determined. Then, based on findings, the minimum value of the leakage reactance of the converter transformer within the leakage reactance range is given. This improves the transient stability of AC / DC hybrid power grids.

Description

Technical Field

[0001] This invention relates to the field of transient stability technology for AC / DC hybrid power grids, specifically to a method for selecting DC main equipment parameters to improve the transient stability of AC / DC hybrid power grids, a device for selecting DC main equipment parameters in AC / DC hybrid power grids, a computer-readable medium storing a device parameter selection program, and an electronic device. Background Technology

[0002] In recent years, with the commissioning of numerous ultra-high-voltage direct current (UHVDC) projects, hybrid AC / DC power grids have gradually taken shape. Currently, the distribution of UHVDC and AC projects is unbalanced, exhibiting a "strong DC, weak AC" characteristic, altering the master-slave relationship between AC and DC systems. Against this backdrop, on the one hand, the infeedback from UHVDC projects replaces some conventional power sources at the receiving end, reducing the inertia and stability of the AC system; on the other hand, the electrical coupling between AC and DC systems makes the stability of the AC system significantly affected by DC transient behavior. DC transient behavior primarily depends on the parameters of the DC main equipment and the mode and parameters of the control system. Therefore, the design of the main equipment parameters for the DC system should comprehensively consider the stability of the receiving-end power grid.

[0003] The main circuit of a DC transmission system includes equipment such as converters, converter transformers, filters, and smoothing reactors, and is the most important component of the DC system. Currently, the selection of main circuit parameters during the design phase mainly considers the safe operation requirements of the DC system itself. For example, the optimized design of the converter transformer leakage reactance mainly considers two factors: its reactive power consumption on the converter and its coordination with the transient overcurrent capability of the converter valve; the selection of smoothing reactors mainly considers factors such as the rise rate of DC current, the possibility of commutation failure caused by faults in the DC receiving-end system, and DC current ripple. However, the aforementioned equipment parameter selection does not consider their impact on the stability of the AC system.

[0004] In AC / DC hybrid systems, after a large disturbance, the DC transient response causes changes in the electrical quantities of the converter bus, which in turn triggers interactive power fluctuations between the two systems. Power angle stability and voltage stability are related to active and reactive power, respectively, thus affecting the corresponding stability issues. The leakage reactance of the converter transformer determines the commutation time of the converter, affecting the active power transmitted and the reactive power consumed by the system. The inductance value of the smoothing reactor affects the DC current variation characteristics during the transient process, thereby affecting the interactive active and reactive power between the AC and DC systems. Therefore, analyzing and studying the correlation between the main equipment parameters and DC transient characteristics, and clarifying the impact of parameter changes on the transient stability of the AC / DC system, provides guidance for the design of DC main equipment parameters and is of great significance for improving system stability. Summary of the Invention

[0005] The purpose of this invention is to provide a method for selecting DC main equipment parameters to improve the transient stability of AC / DC hybrid power grids, a device for selecting DC main equipment parameters in AC / DC hybrid power grids, a computer-readable medium storing a device parameter selection program, and an electronic device, so as to improve the transient stability of AC / DC hybrid power grids.

[0006] The technical solution of this invention is:

[0007] A method for selecting DC main equipment parameters to improve the transient stability of an AC / DC hybrid power grid, wherein the AC / DC hybrid power grid includes a DC system and an AC network, comprising the following steps:

[0008] Step 1: Determine the leakage reactance range of the converter transformer to meet the safe operation requirements of the DC system;

[0009] Step 2: When constructing the DC system, ensure that the leakage reactance of the converter transformer is the minimum value within the leakage reactance range.

[0010] Preferably, in step 1, the rated DC current I of the DC system is obtained. dN The maximum surge current I that a thyristor can withstand M Rated capacity S of the converter valve N and AC system short-circuit capacity S sc ;

[0011] like The leakage reactance range of the converter transformer is [0.12, 0.22]; if The leakage reactance range of the converter transformer is as follows: like The leakage reactance range of the converter transformer is {0.22}; if The leakage reactance range of the converter transformer is as follows:

[0012] Preferably, in step 1, the inductance range of the smoothing reactor is determined to meet the safe operation requirements of the DC system. In step 2, when constructing the DC system, the inductance of the smoothing reactor is also made to be the maximum value of the inductance range.

[0013] More preferably, in step 1, the rated DC voltage U of the DC system is obtained. dN and rated DC current I dN The inductance range of the smoothing reactor is:

[0014] A parameter selection device for DC main equipment in an AC / DC hybrid power grid includes a leakage reactance range calculation device for converter transformers and a leakage reactance optimization device for converter transformers. The leakage reactance range calculation device for converter transformers is used to output the leakage reactance range of converter transformers when the safe operation requirements of the DC system are met, and the leakage reactance optimization device for converter transformers is used to output the minimum value of the leakage reactance range of converter transformers.

[0015] Preferably, the leakage reactance range calculation device of the converter transformer is used to obtain the rated DC current I of the DC system. dN The maximum surge current I that a thyristor can withstand M Rated capacity S of the converter valve N AC system short-circuit capacity S sc ,exist At that time, the leakage reactance range calculation device of the converter transformer outputs the leakage reactance range of the converter transformer as [0.12, 0.22]; if At that time, the leakage reactance range calculation device of the converter transformer outputs the leakage reactance range of the converter transformer as follows: like When the leakage reactance range calculation device of the converter transformer outputs the leakage reactance range of the converter transformer as {0.22}; if At that time, the leakage reactance range calculation device of the converter transformer outputs the leakage reactance range of the converter transformer as follows:

[0016] Preferably, it also includes an inductance range calculation device for the smoothing reactor and an inductance optimization device for the smoothing reactor. The inductance range calculation device for the smoothing reactor is used to output the inductance range of the smoothing reactor under the condition of satisfying the safe operation of the DC system, and the inductance optimization device for the smoothing reactor is used to output the maximum value of the inductance range of the smoothing reactor.

[0017] More preferably, the inductance range calculation device of the smoothing reactor is used to obtain the rated DC voltage U of the DC system. dN Rated DC current I dN The output inductance range of the smoothing reactor is...

[0018] A computer-readable medium storing a device parameter selection program, which, when executed by a processor, implements the steps of the aforementioned method.

[0019] An electronic device includes a memory and one or more processors, the memory being used to store one or more programs; when the one or more programs are executed by the one or more processors, they implement the aforementioned method.

[0020] The stability of the AC network is characterized by the transient potential energy index injected into the AC network through node C during a transient process. In the same AC / DC hybrid power grid, the same fault is applied, and the corresponding transient potential energies are obtained by selecting converter transformers with different leakage reactances. Comparison shows that the smaller the leakage reactance of the converter transformer, the more stable the AC network. Similarly, the stability of the AC network is characterized by the transient potential energy index injected into the AC network through node C during a transient process. In the same AC / DC hybrid power grid, the same fault is applied, and the corresponding transient potential energies are obtained by selecting smoothing reactors with different inductances. Comparison shows that the larger the inductance of the smoothing reactor, the more stable the AC network.

[0021] The beneficial effects of this invention are:

[0022] 1. A method for selecting DC main equipment parameters to improve the transient stability of an AC / DC hybrid power grid, as disclosed in this invention, includes step 1, determining the leakage reactance range of the converter transformer to meet the safe operation requirements of the DC system; this ensures that the leakage reactance of the converter transformer meets the requirements for safe operation of the DC system. Based on the finding that "the smaller the leakage reactance of the converter transformer, the more stable the AC network," step 2, when constructing the DC system, ensures that the leakage reactance of the converter transformer is the minimum value within the leakage reactance range. This improves the transient stability of the AC / DC hybrid power grid while meeting the requirements for safe operation of the DC system.

[0023] 2. The present invention provides a method for selecting DC main equipment parameters to improve the transient stability of an AC / DC hybrid power grid. Step 1 further determines the inductance range of the smoothing reactor to meet the safe operation requirements of the DC system. This ensures that the inductance of the smoothing inductor meets the requirements for safe operation of the DC system. Based on the finding that "the larger the inductance of the smoothing reactor, the more stable the AC network," in step 2, when constructing the DC system, the inductance of the smoothing reactor is also set to the maximum value within the inductance range. This improves the transient stability of the AC / DC hybrid power grid while ensuring the safe operation of the DC system.

[0024] 3. The present invention provides a parameter selection device for DC main equipment in an AC / DC hybrid power grid. Under the condition of only considering the safety operation constraints of the DC system, the leakage reactance range of the converter transformer is determined by a leakage reactance range calculation device. Then, based on the discovery that "the smaller the leakage reactance of the converter transformer, the more stable the AC network", the minimum value of the leakage reactance range is selected by a leakage reactance optimization device of the converter transformer, thereby improving the transient stability of the AC / DC hybrid power grid under the condition of satisfying the safety operation of the DC system.

[0025] 4. The present invention provides a DC main equipment parameter selection device in an AC / DC hybrid power grid. Considering only the constraints of DC system safe operation, it also outputs the inductance range of the smoothing reactor under the condition of satisfying the safe operation of the DC system through an inductance range calculation device. Based on the discovery that "the larger the inductance of the smoothing reactor, the more stable the AC network," it outputs the maximum value of the inductance range of the smoothing reactor through an inductance optimization device, thereby improving the transient stability of the AC / DC hybrid power grid while satisfying the safe operation of the DC system.

[0026] 5. A computer-readable medium storing a device parameter selection program, wherein when the device parameter selection program is executed by a processor, the steps of the DC main equipment parameter selection method for improving the transient stability of the AC / DC hybrid power grid of the present invention are implemented, thereby improving the transient stability of the constructed AC / DC hybrid power grid while meeting the requirements for safe operation of the DC system.

[0027] 6. The electronic device of the present invention includes a memory and one or more processors, wherein the memory is used to store one or more programs; when the one or more programs are executed by one or more processors, the method for selecting DC main equipment parameters to improve the transient stability of AC / DC hybrid power grids of the present invention is implemented, thereby improving the transient stability of the constructed AC / DC hybrid power grid while meeting the requirements for safe operation of the DC system. Attached Figure Description

[0028] Figure 1 This is the equivalent structure diagram of an AC / DC hybrid system.

[0029] Figure 2 This is the equivalent circuit for the inverter commutation process.

[0030] Figure 3 This is a topology diagram of an AC / DC hybrid system.

[0031] Figure 4 This is a graph showing the change in transient dynamic energy as a function of the converter transformer leakage reactance.

[0032] Figure 5 The graph shows the change in transient state energy as a function of the inductance of the smoothing reactor. Detailed Implementation

[0033] The present invention will now be described with reference to the accompanying drawings and embodiments to assist those skilled in the art in understanding and implementing the invention. Unless otherwise stated, the following embodiments and the technical terms therein should not be understood without a background of technical knowledge in this field.

[0034] For AC / DC hybrid systems, the DC system outside the AC network, the generators and loads in the AC system, and other components are equivalent to two-port systems and represented by the injected active power P and reactive power Q.

[0035] See Figure 1 Define the power variable associated with the i-th node of the power network as follows:

[0036]

[0037]

[0038] In the formula, P ni Let Q be the active power flowing into node i. ni Let i be the reactive power flowing into node i. Let i be the voltage phase angle at node i. Let P be the voltage at node i. bi Q represents the active power flowing from node i into node j. bi Let be the reactive power flowing from node i into node j, where j is the branch number connected to node i.

[0039] Define the network matrix A∈R m×l As shown below, where m is the number of nodes in the communication network and l is the number of branches in the communication network.

[0040]

[0041] According to Kirchhoff's laws, we have...

[0042]

[0043] in,

[0044]

[0045] Easy to obtain

[0046]

[0047] Based on the principles of energy flow and conservation, all energy injected from external nodes is converted into the network's potential energy, which serves as the medium for energy interaction between the network and the generator. Assuming the DC system is connected to the AC network through node c, the potential power of the DC system at node c is...

[0048]

[0049] In the formula, P nC Q represents the active power flowing into node C. nC The reactive power flowing into node C, The differential of the voltage phase angle at node C, The voltage derivative at node C;

[0050] According to the potential energy power formula, after eliminating the steady-state component and integrating, the transient potential energy injected into the AC network through port c by the DC system during the transient process can be obtained.

[0051]

[0052] In the formula, P nC Q represents the active power flowing into node C. nC The reactive power flowing into node C, The differential of the voltage phase angle at node C, P is the differential of the voltage at node C. nCs Q represents the active power flowing into node C under steady-state conditions. nCs This represents the reactive power flowing into node C under steady-state conditions. This is the differential of the voltage phase angle at node C under steady state. This is the voltage differential at node C under steady-state conditions.

[0053] Generally, the active power and reactive power flowing into node C under steady state, as well as the voltage phase angle differential and voltage differential at node C under steady state, can be the theoretical active power and reactive power flowing into node C, and the voltage phase angle differential and voltage differential at node C when designing an AC / DC hybrid power grid.

[0054] The transient potential energy injected into the AC network through port C during a transient process reflects the impact of DC transient characteristics on the stability of the AC system. During a transient process, the kinetic energy of the generator and the transient energy of external disturbances are all converted into the potential energy of the network. The stability of the system depends on the relative relationship between the network's ability to absorb transient energy and the externally injected transient potential energy. Due to the coupling effect between the AC and DC systems, the LCC is a non-autonomous disturbance node. When the potential power generated by the power input to the AC system is larger, it increases the burden on the network to absorb transient power, which is detrimental to system stability; when its potential power is smaller, it reduces the burden on the network to absorb transient power, which is beneficial to system stability. Therefore, this index can quantitatively characterize the magnitude of the impact of DC transient response on AC system stability under different operating conditions.

[0055] The influence of the parameters of DC main equipment such as converter transformers and smoothing reactors on the transient dynamic performance of the index is analyzed, so as to obtain the changing trend of AC system transient stability capability when the parameters of DC main equipment change;

[0056] The process of current transferring from the thyristor to be turned off to the thyristor to be turned on is called the commutation process. Due to the equivalent inductance of the commutator transformer, after the trigger pulse is applied, the current in the thyristor to be turned off cannot immediately decrease to zero; that is, the commutation process cannot be completed instantaneously. The electrical angle corresponding to the duration of this commutation process is the commutation overlap angle μ. The trigger delay angle α, the commutation overlap angle μ, and the arc extinction angle γ satisfy the relationship α + μ + γ = π. The equivalent circuit of the commutation process is shown below. Figure 2 As shown.

[0057] From the equivalent circuit, we can obtain that

[0058]

[0059] i1+i9=I d (10)

[0060] In the formula, L c For the equivalent leakage inductance of the converter transformer, U Ya Let U be the voltage of phase a. Yc I is the phase c voltage, i1 is the current flowing through thyristor 1, i9 is the current flowing through thyristor 9, and I... d This refers to the DC current transmitted to the system.

[0061] The reactive power consumption of the converter mainly comes from the commutation process. With the DC transmission power and firing angle remaining constant, the reactive power consumption of the converter increases with the increase of its leakage reactance.

[0062] Q d =P d tan[arccos(cosα-πfL c (11)

[0063] In the formula, P d and Q d These represent the active and reactive power transmitted by the converter, respectively, where α is the trigger delay angle, and L... c Here, f is the equivalent leakage inductance of the converter transformer, and f is the system frequency.

[0064] The short-circuit impedance of the converter transformer affects the commutation overlap angle. The larger the impedance, the longer the commutation process, and the more reactive power the converter absorbs. This makes it more difficult to restore the converter bus voltage, affecting the reactive power and voltage specifications, which is detrimental to system stability.

[0065] For DC transmission systems, smoothing reactors are generally installed at the DC-side outlet of the converter to suppress the rate of rise of DC current caused by system disturbances and to avoid DC current discontinuity under light loads. In addition to the above main functions, smoothing reactors also have the function of suppressing DC line harmonics.

[0066] The larger the inductance of the smoothing reactor, the slower and smaller the response characteristics of DC current and power during transient processes, and the smaller the influence of DC on AC transient processes.

[0067] For specific AC / DC hybrid systems, further simulation analysis can be conducted to determine the change in transient dynamic energy increment with the leakage reactance of the converter transformer and the smoothing reactor under the same large disturbance, thereby obtaining its impact on the transient stability of the AC system.

[0068] Considering the operating performance and techno-economic efficiency of the DC system itself, and taking into account the impact of DC main equipment parameters on the transient stability of the system during transient processes, recommendations for selecting DC main equipment parameters are given.

[0069] Existing converter transformer leakage reactance optimization design mainly considers two factors: its reactive power consumption on the converter and its coordination with the transient overcurrent capability of the converter valve. Moreover, whether the leakage reactance is higher than 22% or lower than 12%, it will increase the manufacturing difficulty of the converter transformer. Therefore, in order to improve the transient stability capability of the system, the value of the converter transformer leakage reactance should be as small as possible within this range.

[0070] Smoothing reactors have the functions of smoothing DC current ripple and preventing commutation failure. Under the premise of ensuring that the transient overvoltage requirements are met, the inductance of the smoothing reactor can be as large as possible in order to improve the transient stability of the AC-DC hybrid system.

[0071] Specifically, with Figure 3 The AC / DC hybrid system shown is illustrated as an example. Its inverter side is connected to a 500kV AC network, and the DC system is a single-pole double twelve-pulse ±800kV UHVDC transmission line.

[0072] The DC system is equivalent to a two-port system.

[0073] A three-phase metallic short-circuit fault is applied to branch AB, and the fault is cleared after 0.11s. Simulation analysis is performed on the transformer leakage reactance at 0.18pu, 0.3pu, and 0.4pu. Figure 4 As shown, with the increase of the leakage reactance of the converter transformer, the system is more prone to commutation failure and absorbs more reactive power. The index also increases with the increase of the leakage reactance of the converter transformer, indicating that the larger the leakage reactance of the converter transformer, the more detrimental it is to the stability of the AC / DC hybrid system.

[0074] A three-phase metallic short-circuit fault was applied to branch AB, and the fault was cleared after 0.13s. The performance parameters of the original smoothing reactor at 500mH, 800mH, and 1000mH are as follows. Figure 5As shown, with the increase of smoothing reactance, the DC current fluctuation decreases, resulting in a smaller DC transmission power fluctuation. The index also decreases with the increase of converter transformer leakage reactance, indicating that a larger leakage reactance of the converter transformer is more beneficial to the stability of the AC / DC hybrid system.

[0075] Example 1: A method for selecting DC main equipment parameters to improve the transient stability of an AC / DC hybrid power grid, wherein the AC / DC hybrid power grid includes a DC system and an AC network, comprising the following steps:

[0076] Step 1: Determine the leakage reactance range of the converter transformer to meet the safe operation requirements of the DC system. In this step, only the DC system constraints are considered, and the mutual influence between the DC system and the AC network is not considered, thus obtaining the leakage reactance range of the converter transformer.

[0077] Leakage reactance u of converter transformer k The surge current level of the thyristor converter valve should be met, i.e.

[0078]

[0079] In the formula, I dN For the rated DC current, I M S is the maximum surge current that the thyristor can withstand. N S is the rated capacity of the converter valve. sc For the short-circuit capacity of the AC system;

[0080] The leakage reactance range of the converter transformer is:

[0081] Furthermore, when designing converter transformer circuits, the leakage reactance of the converter transformer should be limited to 12% ≤ u. k The manufacturing difficulty of converter transformers is limited to ≤22%. When designing DC systems, the safety requirements for DC system operation are more important than the manufacturing cost requirements of converter transformers; therefore, in... Although Since the set is empty, we need to disregard the manufacturing difficulty of the converter transformer. Therefore, the leakage reactance range of the converter transformer is... At this time, the manufacturing difficulty of converter transformers was also taken into account.

[0082] Based on the above, we get: If The leakage reactance range of the converter transformer is [0.12, 0.22]; if The leakage reactance range of the converter transformer is as follows: like The leakage reactance range of the converter transformer is {0.22}; if The leakage reactance range of the converter transformer is as follows:

[0083] Step 2: When constructing the DC system, ensure that the leakage reactance of the converter transformer is the minimum value within the leakage reactance range, that is, if... The leakage reactance of the converter transformer is 0.12; if The leakage reactance of the converter transformer is

[0084] Constructing a DC system can be understood as constructing a DC system when designing an AC / DC hybrid power grid, or as constructing a DC system when installing an AC / DC hybrid power grid.

[0085] Example 2: A method for selecting DC main equipment parameters to improve the transient stability of an AC / DC hybrid power grid, the AC / DC hybrid power grid including a DC system and an AC network, comprising the following steps:

[0086] Step 1: Determine the leakage reactance range of the converter transformer and the inductance range of the smoothing reactor to meet the safe operation requirements of the DC system. In this step, only the DC system constraints are considered, and the mutual influence between the DC system and the AC network is not considered. The leakage reactance range of the converter transformer and the inductance range of the smoothing reactor are obtained.

[0087] Leakage reactance u of converter transformer k The surge current level of the thyristor converter valve should be met, i.e.

[0088]

[0089] In the formula, I dN For the rated DC current, I M S is the maximum surge current that the thyristor can withstand. N S is the rated capacity of the converter valve. sc For the short-circuit capacity of the AC system;

[0090] The leakage reactance range of the converter transformer is:

[0091] Furthermore, when designing converter transformer circuits, the leakage reactance of the converter transformer should be limited to 12% ≤ u. k The manufacturing difficulty of converter transformers is limited to ≤22%. When designing DC systems, the safety requirements for DC system operation are more important than the manufacturing cost requirements of converter transformers; therefore, in... Although Since the set is empty, we need to disregard the manufacturing difficulty of the converter transformer. Therefore, the leakage reactance range of the converter transformer is... At this time, the manufacturing difficulty of converter transformers was also taken into account.

[0092] Based on the above, we get: If The leakage reactance range of the converter transformer is [0.12, 0.22]; if The leakage reactance range of the converter transformer is as follows: like The leakage reactance range of the converter transformer is {0.22}; if The leakage reactance range of the converter transformer is as follows:

[0093] Smoothing reactor inductor L i The range is specifically defined as follows: the inductance L of the smoothing reactor is determined according to the rate of rise of the DC current during disturbance. i The inductance range, i.e.

[0094]

[0095] In the formula, I dN For the rated DC current, U dN For the rated DC voltage, S i This is the current slope coefficient;

[0096] Based on the above, we can conclude that the inductance range of the smoothing reactor is:

[0097] Step 2: When constructing the DC system, ensure that the leakage reactance of the converter transformer is the minimum value within the leakage reactance range, that is, if... The leakage reactance of the converter transformer is 0.12; if The leakage reactance of the converter transformer is To make the inductance of the smoothing reactor the maximum value within the inductance range, that is, to make the inductance of the smoothing reactor the maximum value within the range.

[0098] Constructing a DC system can be understood as constructing a DC system when designing an AC / DC hybrid power grid, or as constructing a DC system when installing an AC / DC hybrid power grid.

[0099] Example 3: A method for selecting DC main equipment parameters to improve the transient stability of AC / DC hybrid power grids, comprising the following steps:

[0100] Step 1: Determine the leakage reactance range of the converter transformer to ensure safe operation of the DC system. Specifically, based on existing technology, determine the leakage reactance u of the converter transformer. k Limit to 12% ≤ u k ≤22% to limit the manufacturing cost of converter transformers; limit the leakage reactance of converter transformers. (I dN For the rated DC current, I M S is the maximum surge current that the thyristor can withstand. N S is the rated capacity of the converter valve. sc(To ensure the short-circuit capacity of the AC system meets the surge current level of the thyristor converter valve.) The intersection of the two ranges is taken as the range for the leakage reactance of the converter transformer.

[0101] Step 2: Determine the inductance range of the smoothing reactor to ensure safe operation of the DC system. Specifically, determine the inductance L of the smoothing reactor according to the rate at which the DC current rises during disturbances is suppressed. i scope, (where I) dN For the rated DC current, U dN For the rated DC current, S i (current slope coefficient)

[0102] Step 3: Calculate the impact of the transient characteristics of the DC system on the transient stability of the AC network. Specifically, the DC system is equivalent to a two-port system; the DC system is connected to the AC network through node C, and the active power P flowing into node C is measured at constant intervals. nC Reactive power Q nC Voltage phase angle at node C and the voltage at node C When designing an AC / DC hybrid power grid, the theoretical active power P flowing into node C is obtained. nCs Reactive power Q nCs Voltage phase angle at node C and the voltage at node C

[0103] During the transient process, the DC system injects transient potential energy into the AC network through node C.

[0104]

[0105] Step 4: Based on the transient potential energy proposed in Step 3, determine the correlation between the leakage reactance of the converter transformer and the inductance of the smoothing reactor and the stability of the AC network through simulation.

[0106] Step 5: Based on steps 1 and 2, in order to improve the stability of the AC system, determine the leakage reactance value of the converter transformer and the inductance value of the smoothing reactor. Specifically, the leakage reactance of the converter transformer is the minimum value of the leakage reactance range, and the inductance of the smoothing reactor is the maximum value of the inductance range.

[0107] Example 4: A parameter selection device for DC main equipment in an AC / DC hybrid power grid, comprising a leakage reactance range calculation device for converter transformers and a leakage reactance optimization device for converter transformers. The leakage reactance range calculation device for converter transformers is used to output the leakage reactance range of converter transformers when the safe operation requirements of the DC system are met. The leakage reactance optimization device for converter transformers is used to output the minimum value of the leakage reactance range of converter transformers.

[0108] In use, the leakage reactance range calculation device for the converter transformer is used to obtain the rated DC current I of the DC system. dN The maximum surge current I that a thyristor can withstand M Rated capacity S of the converter valve N AC system short-circuit capacity S sc ,exist At that time, the leakage reactance range calculation device for the converter transformer outputs a leakage reactance range of [0.12, 0.22] for the converter transformer; the leakage reactance optimization device for the converter transformer is used to output a leakage reactance of 0.12 for the converter transformer. At that time, the leakage reactance range calculation device of the converter transformer outputs the leakage reactance range of the converter transformer as follows: The leakage reactance optimization device for the converter transformer is used to output the leakage reactance of the converter transformer. exist At that time, the leakage reactance range calculation device of the converter transformer outputs the leakage reactance range of the converter transformer as follows: The leakage reactance optimization device for the converter transformer is used to output the leakage reactance of the converter transformer.

[0109] Example 5: A parameter selection device for DC main equipment in an AC / DC hybrid power grid, comprising a leakage reactance range calculation device for converter transformers, an inductance range calculation device for smoothing reactors, a leakage reactance optimization device for converter transformers, and an inductance optimization device for smoothing reactors. The leakage reactance range calculation device for converter transformers is used to output the leakage reactance range of converter transformers when the safe operation requirements of the DC system are met. The inductance range calculation device for smoothing reactors is used to output the inductance range of smoothing reactors under the condition of safe operation of the DC system. The leakage reactance optimization device for converter transformers is used to output the minimum value of the leakage reactance range of converter transformers. The inductance optimization device for smoothing reactors is used to output the maximum value of the inductance range of smoothing reactors.

[0110] In use, the leakage reactance range calculation device for the converter transformer is used to obtain the rated DC current I of the DC system. dN The maximum surge current I that a thyristor can withstand M Rated capacity S of the converter valve N AC system short-circuit capacity S sc ,exist At that time, the leakage reactance range calculation device for the converter transformer outputs a leakage reactance range of [0.12, 0.22] for the converter transformer; the leakage reactance optimization device for the converter transformer is used to output a leakage reactance of 0.12 for the converter transformer. At that time, the leakage reactance range calculation device of the converter transformer outputs the leakage reactance range of the converter transformer as follows: The leakage reactance optimization device for the converter transformer is used to output the leakage reactance of the converter transformer. exist At that time, the leakage reactance range calculation device of the converter transformer outputs the leakage reactance range of the converter transformer as follows: The leakage reactance optimization device for the converter transformer is used to output the leakage reactance of the converter transformer. The inductance range calculation device for smoothing reactors is used to obtain the rated DC voltage U of the DC system. dN Rated DC current I dN The output inductance range of the smoothing reactor is... The inductance optimization device for smoothing reactors is used to output the inductance of the smoothing reactor.

[0111] Example 6: A computer-readable medium storing a device parameter selection program, the device parameter selection program including an input module, a calculation module, and an output module; the input module is used to receive and acquire the rated DC current I of the DC system. dN The maximum surge current I that a thyristor can withstand M Rated capacity S of the converter valve N AC system short-circuit capacity S sc The computing module is used for calculation. And comparison and the size of 0.12; if At that time, the output module is used to output the leakage reactance of the converter transformer as 0.12; if At that time, the output module is used to output the leakage reactance of the converter transformer.

[0112] Example 7: A computer-readable medium storing a device parameter selection program, the device parameter selection program including an input module, a calculation module, and an output module; the input module is used to receive and acquire the rated DC voltage U of the DC system. dN Rated DC current I dN The maximum surge current I that a thyristor can withstand M Rated capacity S of the converter valve N AC system short-circuit capacity S sc The computing module is used for calculation. And comparison and the size of 0.12; if At that time, the output module is used to output the leakage reactance of the converter transformer as 0.12 and the inductance of the smoothing reactor as... like At that time, the output module is used to output the leakage reactance of the converter transformer. The inductance of the smoothing reactor is

[0113] Example 8: A computer-readable medium storing a device parameter selection program, which, when executed by a processor, performs the following steps:

[0114] Step 1: Determine the leakage reactance range of the converter transformer under the condition of ensuring safe operation of the DC system; specifically,

[0115] In step 1, the rated DC current I of the DC system is obtained. dN The maximum surge current I that a thyristor can withstand M Rated capacity S of the converter valve N and AC system short-circuit capacity S sc ;

[0116] like The leakage reactance range of the converter transformer is [0.12, 0.22]; if The leakage reactance range of the converter transformer is as follows: like The leakage reactance range of the converter transformer is {0.22}; if The leakage reactance range of the converter transformer is as follows:

[0117] Step 2: When constructing the DC system, ensure that the leakage reactance of the converter transformer is the minimum value within the leakage reactance range, i.e., if... The leakage reactance of the converter transformer is 0.12; if The leakage reactance of the converter transformer is

[0118] Example 9: A computer-readable medium storing a device parameter selection program, which, when executed by a processor, performs the following steps:

[0119] Step 1: Determine the leakage reactance range of the converter transformer and the inductance range of the smoothing reactor to meet the safe operation requirements of the DC system. In this step, only the DC system constraints are considered, and the mutual influence between the DC system and the AC network is not considered. The leakage reactance range of the converter transformer and the inductance range of the smoothing reactor are obtained.

[0120] Leakage reactance u of converter transformer k The surge current level of the thyristor converter valve should be met, i.e.

[0121]

[0122] In the formula, I dN For the rated DC current, I M S is the maximum surge current that the thyristor can withstand. N S is the rated capacity of the converter valve.sc For the short-circuit capacity of the AC system;

[0123] The leakage reactance range of the converter transformer is:

[0124] Furthermore, when designing converter transformer circuits, the leakage reactance of the converter transformer should be limited to 12% ≤ u. k The manufacturing difficulty of converter transformers is limited to ≤22%. When designing DC systems, the safety requirements for DC system operation are more important than the manufacturing cost requirements of converter transformers; therefore, in... Although Since the set is empty, we need to disregard the manufacturing difficulty of the converter transformer. Therefore, the leakage reactance range of the converter transformer is... At this time, the manufacturing difficulty of converter transformers was also taken into account.

[0125] Based on the above, we get: If The leakage reactance range of the converter transformer is [0.12, 0.22]; if The leakage reactance range of the converter transformer is as follows: like The leakage reactance range of the converter transformer is {0.22}; if The leakage reactance range of the converter transformer is as follows:

[0126] Smoothing reactor inductor L i The range is specifically defined as follows: the inductance L of the smoothing reactor is determined according to the rate of rise of the DC current during disturbance. i The inductance range, i.e.

[0127]

[0128] In the formula, I dN For the rated DC current, U dN For the rated DC voltage, S i This is the current slope coefficient;

[0129] Based on the above, we can conclude that the inductance range of the smoothing reactor is:

[0130] Step 2: When constructing the DC system, ensure that the leakage reactance of the converter transformer is the minimum value within the leakage reactance range, that is, if... The leakage reactance of the converter transformer is 0.12; if The leakage reactance of the converter transformer is To make the inductance of the smoothing reactor the maximum value within the inductance range, that is, to make the inductance of the smoothing reactor the maximum value within the range.

[0131] Example 10: An electronic device includes a memory and one or more processors, the memory being used to store one or more programs; when the one or more programs are executed by the one or more processors, the following steps are performed:

[0132] Step 1: Determine the leakage reactance range of the converter transformer under the condition of ensuring safe operation of the DC system; specifically,

[0133] In step 1, the rated DC current I of the DC system is obtained. dN The maximum surge current I that a thyristor can withstand M Rated capacity S of the converter valve N and AC system short-circuit capacity S sc ;

[0134] like The leakage reactance range of the converter transformer is [0.12, 0.22]; if The leakage reactance range of the converter transformer is as follows: like The leakage reactance range of the converter transformer is {0.22}; if The leakage reactance range of the converter transformer is as follows:

[0135] Step 2: When constructing the DC system, ensure that the leakage reactance of the converter transformer is the minimum value within the leakage reactance range, i.e., if... The leakage reactance of the converter transformer is 0.12; if The leakage reactance of the converter transformer is

[0136] Example 11: An electronic device includes a memory and one or more processors, the memory being used to store one or more programs; when the one or more programs are executed by the one or more processors, the following steps are performed:

[0137] Step 1: Determine the leakage reactance range of the converter transformer and the inductance range of the smoothing reactor to meet the safe operation requirements of the DC system. In this step, only the DC system constraints are considered, and the mutual influence between the DC system and the AC network is not considered. The leakage reactance range of the converter transformer and the inductance range of the smoothing reactor are obtained.

[0138] Leakage reactance u of converter transformer k The surge current level of the thyristor converter valve should be met, i.e.

[0139]

[0140] In the formula, I dN For the rated DC current, I M S is the maximum surge current that the thyristor can withstand.N S is the rated capacity of the converter valve. sc For the short-circuit capacity of the AC system;

[0141] The leakage reactance range of the converter transformer is:

[0142] Furthermore, when designing converter transformer circuits, the leakage reactance of the converter transformer should be limited to 12% ≤ u. k The manufacturing difficulty of converter transformers is limited to ≤22%. When designing DC systems, the safety requirements for DC system operation are more important than the manufacturing cost requirements of converter transformers; therefore, in... Although Since the set is empty, we need to disregard the manufacturing difficulty of the converter transformer. Therefore, the leakage reactance range of the converter transformer is... At this time, the manufacturing difficulty of converter transformers was also taken into account.

[0143] Based on the above, we get: If The leakage reactance range of the converter transformer is [0.12, 0.22]; if The leakage reactance range of the converter transformer is as follows: like The leakage reactance range of the converter transformer is {0.22}; if The leakage reactance range of the converter transformer is as follows:

[0144] Smoothing reactor inductor L i The range is specifically defined as follows: the inductance L of the smoothing reactor is determined according to the rate of rise of the DC current during disturbance. i The inductance range, i.e.

[0145]

[0146] In the formula, I dN For the rated DC current, U dN For the rated DC voltage, S i This is the current slope coefficient;

[0147] Based on the above, we can conclude that the inductance range of the smoothing reactor is:

[0148] Step 2: When constructing the DC system, ensure that the leakage reactance of the converter transformer is the minimum value within the leakage reactance range, that is, if... The leakage reactance of the converter transformer is 0.12; if The leakage reactance of the converter transformer is To make the inductance of the smoothing reactor the maximum value within the inductance range, that is, to make the inductance of the smoothing reactor the maximum value within the range.

[0149] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. It should be understood that it is impossible to exhaustively describe all possible implementations in practice; the inventive concept of the present invention is illustrated to the extent possible through examples. Without departing from the inventive concept of the present invention and without any creative effort, any specific embodiments formed by selecting and combining technical features in the above embodiments, experimentally changing specific parameters, or conventionally replacing the disclosed technical means of the present invention using existing technology should be considered as implicit disclosures of the present invention.

Claims

1. A method for selecting DC main equipment parameters to improve the transient stability of an AC / DC hybrid power grid, wherein the AC / DC hybrid power grid includes a DC system and an AC network, characterized in that, Includes the following steps: Step 1: Determine the leakage reactance range of the converter transformer to meet the safe operation requirements of the DC system; Step 2: When constructing the DC system, ensure that the leakage reactance of the converter transformer is the minimum value within the leakage reactance range, where: In step 1, the inductance range of the smoothing reactor is determined to meet the safe operation requirements of the DC system. In step 2, when constructing the DC system, the inductance of the smoothing reactor is made to be the maximum value of the inductance range. In step 1, the rated DC current of the DC system is obtained. The maximum surge current that a thyristor can withstand. Rated capacity of the converter valve and AC system short-circuit capacity ; like Then the leakage reactance range of the converter transformer is [0.12, 0.22]; if The leakage reactance range of the converter transformer is then... ;like Then the leakage reactance range of the converter transformer is {0.22}; if The leakage reactance range of the converter transformer is then... ; In step 1, the rated DC voltage of the DC system is obtained. and rated DC current The inductance range of the smoothing reactor is: .

2. A device for selecting parameters of DC main equipment in an AC / DC hybrid power grid, characterized in that, The system includes a leakage reactance range calculation device for converter transformers and a leakage reactance optimization device for converter transformers. The leakage reactance range calculation device is used to output the leakage reactance range of converter transformers when the requirements for safe operation of DC system are met. The leakage reactance optimization device is used to output the minimum value of the leakage reactance range of converter transformers. It also includes an inductance range calculation device and an inductance optimization device for the smoothing reactor. The inductance range calculation device is used to output the inductance range of the smoothing reactor under the condition of safe operation of the DC system, and the inductance optimization device is used to output the maximum value of the inductance range of the smoothing reactor; wherein: The leakage reactance range calculation device of the converter transformer is used to obtain the rated DC current of the DC system. The maximum surge current that a thyristor can withstand. Rated capacity of the converter valve AC system short-circuit capacity ,exist The leakage reactance range calculation device for the converter transformer outputs a leakage reactance range of [0.12, 0.22] for the converter transformer; if At that time, the leakage reactance range calculation device of the converter transformer outputs the leakage reactance range of the converter transformer as follows: ;like At that time, the leakage reactance range calculation device of the converter transformer Set the leakage reactance range of the output converter transformer to {0.22}; if At that time, the leakage reactance range of the output converter transformer is ; The inductance range calculation device of the smoothing reactor is used to obtain the rated DC voltage of the DC system. Rated DC current The output inductance range of the smoothing reactor is... .

3. A computer-readable medium storing a device parameter selection program, characterized in that, When the device parameter selection program is executed by the processor, it implements the steps of the method as described in claim 1.

4. An electronic device comprising a memory and one or more processors, the memory being used to store one or more programs; characterized in that, When the one or more programs are executed by the one or more processors, they implement the method as described in claim 1.

Images