An alternating current-direct current hybrid network architecture optimization control method and device based on strong-weak balance

Abstract

The application provides a kind of AC / DC hybrid network architecture optimization control method and device based on strong and weak balance, method includes: constructing the AC / DC hybrid network architecture optimization model considering power flow constraint, short-circuit current constraint, channel and converter station capacity constraint and planning cost;Based on the AC / DC hybrid network architecture optimization model, the current AC / DC hybrid network architecture structure is optimized, and the initial optimization scheme of AC / DC hybrid network architecture is obtained;The voltage stability evaluation and system transient stability evaluation of the initial optimization scheme of AC / DC hybrid network architecture are carried out, and whether the initial optimization scheme of AC / DC hybrid network architecture meets the requirement of strong and weak balance is judged according to the evaluation result;The initial optimization scheme of AC / DC hybrid network architecture that does not meet the requirement of strong and weak balance is adjusted until the optimal AC / DC hybrid network architecture optimization scheme that meets the requirement of strong and weak balance is obtained;The method can maximize to avoid fault influence, improve the robustness of network system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power distribution network, and particularly relates to a method and device for optimization control of AC-DC hybrid network based on strong-weak balance. BACKGROUND

[0002] With the transformation of national energy structure and the increasing of new energy installed capacity, the penetration of new energy will lead to the decrease of system inertia, the shortage of short-circuit capacity, the weakening of the frequency and voltage regulation capability of traditional synchronous generators, and the severe test of voltage and transient stability of AC power grid. Higher demand is put forward for the transmission capacity of network section. Due to the restriction of short-circuit current, the AC transmission capacity is close to saturation, and embedded DC can be considered to enhance the transmission capacity of network section. However, with the introduction of embedded DC, the operation characteristics of AC network change, and the capacity matching between AC system and DC system is needed based on the coupling characteristics of AC-DC hybrid network to meet the normal transmission of power flow under different operating conditions. The introduction of DC line will increase the electrical distance between source and load nodes of AC network, weaken the AC connection of transmission section, and reduce the voltage support capability of network. The decrease of system inertia will also affect the resistance of AC-DC hybrid network to interference. When a short-circuit fault occurs, the system frequency will fluctuate greatly, the oscillation amplitude of power angle curve will increase, and the transient stability will decrease. Therefore, the introduction of embedded DC not only improves the power flow and short-circuit current, but also brings challenges to the stability of AC-DC hybrid network.

[0003] In the face of the complex operation characteristics of AC-DC hybrid network, how to optimize the topology of network structure while considering economy, safety and stability, and break through the technical bottleneck of network development is a problem to be solved. However, most of the existing researches only consider single problems such as power flow and short-circuit current improvement, and cannot completely avoid the influence of faults. For example, Chinese patent application CN110875602A discloses a network reconstruction scheme optimization method for multi-DC feeding system, which includes the following steps: I, determination of the network reconstruction objective function of multi-DC feeding system: including the optimization target of target network and the optimization target of power supply point start-up sequence. II, determination of the constraint conditions in the network reconstruction of multi-DC feeding system: network connectivity constraint, DC start-up constraint, unit start-up constraint, and power flow constraint. III, the established model is solved by using a hybrid particle swarm algorithm in two steps, including target network optimization solving and unit start-up sequence optimization solving. Each part includes particle initialization, fitness calculation, iteration update, etc. The above method cannot completely avoid the influence of faults and cannot effectively improve the voltage stability of power grid. SUMMARY

[0004] The present application provides a method and device for optimization control of AC-DC hybrid network based on strong-weak balance to improve the voltage stability of power grid.

[0005] A strong and weak balance-based AC / DC hybrid network architecture optimization control method, comprising:

[0006] An AC / DC hybrid network architecture optimization model considering flow constraints, short-circuit current constraints, channel and converter station capacity constraints, and planning costs is constructed;

[0007] Based on the AC / DC hybrid network architecture optimization model, the current AC / DC hybrid network architecture structure is optimized to obtain an initial optimization scheme of the AC / DC hybrid network architecture;

[0008] The voltage stability and system transient stability of the initial optimization scheme of the AC / DC hybrid network architecture are evaluated, and whether the initial optimization scheme of the AC / DC hybrid network architecture meets the strong and weak balance requirement is determined according to the evaluation results;

[0009] The initial optimization scheme of the AC / DC hybrid network architecture that does not meet the strong and weak balance requirement is adjusted until an optimal AC / DC hybrid network architecture optimization scheme that meets the strong and weak balance requirement is obtained.

[0010] Further, the AC / DC hybrid network architecture optimization model includes flow constraints, short-circuit current constraints, channel and converter station capacity constraints, and an objective function with the minimum planning cost.

[0011] Further, based on the AC / DC hybrid network architecture optimization model, the current AC / DC hybrid network architecture structure is optimized to obtain an initial optimization scheme of the AC / DC hybrid network architecture, comprising:

[0012] At least one of the following operations is performed on the current AC / DC hybrid network architecture structure: adding a DC line, adding an AC line, and converting an AC line to a DC line, to obtain a candidate scheme. Based on the candidate scheme, an optimization algorithm is used to calculate an initial optimization scheme of the AC / DC hybrid network architecture that meets the flow constraints, short-circuit current constraints, channel and converter station capacity constraints, and minimum planning cost.

[0013] Further, the voltage stability and system transient stability of the initial optimization scheme of the AC / DC hybrid network architecture are evaluated, and whether the initial optimization scheme of the AC / DC hybrid network architecture meets the strong and weak balance requirement is determined according to the evaluation results, comprising:

[0014] According to the voltage of the node corresponding to the network device in the initial optimization scheme of the AC / DC hybrid network architecture, the voltage stiffness of the corresponding node is calculated;

[0015] If the voltage stiffness of all nodes in the initial optimization scheme of the AC / DC hybrid network architecture is greater than a first preset value, it is determined that the initial optimization scheme of the AC / DC hybrid network architecture meets the voltage stability requirement;

[0016] According to the AC channel capacity and the DC channel capacity between all two nodes in the initial optimization scheme of the AC-DC hybrid network, the AC-DC system strength ratio index is calculated;

[0017] If the AC-DC system strength ratio index of all two nodes in the initial optimization scheme of the AC-DC hybrid network is greater than the second preset value, it is determined that the initial optimization scheme of the AC-DC hybrid network meets the system transient stability requirement;

[0018] If the initial optimization scheme of the AC-DC hybrid network meets the voltage stability requirement and the system transient stability requirement at the same time, it is determined that the initial optimization scheme of the AC-DC hybrid network meets the strong-weak balance requirement;

[0019] The initial optimization scheme of the AC-DC hybrid network meeting the strong-weak balance requirement is determined as the optimal AC-DC hybrid network optimization scheme.

[0020] Further, the voltage stiffness is the ratio of the voltage modulus value of the network port when the node corresponds to the access of the network equipment to the no-load voltage when the node corresponds to the non-access of the network equipment.

[0021] Further, the AC-DC system strength ratio index is the ratio between the AC channel capacity and the DC channel capacity between two nodes.

[0022] Further, the initial optimization scheme of the AC-DC hybrid network not meeting the strong-weak balance is adjusted until the optimal AC-DC hybrid network optimization scheme meeting the strong-weak balance requirement is obtained, including:

[0023] For the initial optimization scheme of the AC-DC hybrid network not meeting the voltage stability requirement, a static reactive power compensation device or a VSC DC device is introduced, and the voltage stability of the adjusted initial optimization scheme of the AC-DC hybrid network is evaluated and adjusted again until the voltage stability requirement is met;

[0024] For the initial optimization scheme of the AC-DC hybrid network not meeting the system transient stability requirement, the AC line between the nodes is disconnected, and the system transient stability is evaluated and adjusted again until the system transient stability requirement is met;

[0025] The initial optimization scheme of the AC-DC hybrid network meeting the voltage stability requirement and the system transient stability requirement after adjustment is determined as the optimal AC-DC hybrid network optimization scheme.

[0026] Further, for the initial optimization scheme of the AC-DC hybrid network not meeting the voltage stability requirement, a static reactive power compensation device or a VSC DC device is introduced, including:

[0027] The node with a voltage stiffness less than or equal to the first preset value in the initial optimization scheme of the AC-DC hybrid network not meeting the voltage stability requirement is identified;

[0028] connecting a static reactive power compensation device or a VSC DC device at a node with a voltage stiffness less than or equal to a first preset value.

[0029] Further, for the initial optimization scheme of the AC / DC interconnected network that does not meet the system transient stability requirement, the AC lines between nodes are disconnected, including:

[0030] determining the nodes in the initial optimization scheme of the AC / DC interconnected network that do not meet the system transient stability requirement, with an AC / DC system strength ratio index less than or equal to a second preset value;

[0031] disconnecting the AC lines in the power transmission section between the nodes with the AC / DC system strength ratio index less than or equal to the second preset value.

[0032] An AC / DC interconnected network optimization control device based on strong-weak balance, comprising:

[0033] a model construction module configured to construct an AC / DC interconnected network optimization model considering power flow constraints, short-circuit current constraints, channel and converter station capacity constraints, and planning costs;

[0034] an initial optimization module configured to optimize the current AC / DC interconnected network structure based on the AC / DC interconnected network optimization model, and obtain an initial optimization scheme of the AC / DC interconnected network;

[0035] an evaluation module configured to evaluate the voltage stability and the system transient stability of the initial optimization scheme of the AC / DC interconnected network, and determine whether the initial optimization scheme of the AC / DC interconnected network meets the strong-weak balance requirement according to the evaluation results;

[0036] an adjustment model configured to adjust the initial optimization scheme of the AC / DC interconnected network that does not meet the strong-weak balance requirement until an optimal AC / DC interconnected network optimization scheme that meets the strong-weak balance requirement is obtained.

[0037] Further, the AC / DC interconnected network optimization model includes power flow constraint conditions, short-circuit current constraint conditions, channel and converter station capacity constraint conditions, and an objective function with the minimum planning cost.

[0038] Further, the initial optimization module optimizes the current AC / DC interconnected network structure based on the AC / DC interconnected network optimization model, and obtains an initial optimization scheme of the AC / DC interconnected network, including:

[0039] At least one of the following operations is performed on the current AC / DC hybrid network structure: adding a DC line, adding an AC line, and changing an AC line to a DC line, to obtain a candidate scheme; and an optimization algorithm is used to calculate an initial optimization scheme of the AC / DC hybrid network that meets the power flow constraint condition, the short-circuit current constraint condition, the channel and converter station capacity constraint condition, and has the minimum planning cost based on the candidate scheme.

[0040] Further, the evaluation module evaluates the voltage stability and the system transient stability of the initial optimization scheme of the AC / DC hybrid network, and determines whether the initial optimization scheme of the AC / DC hybrid network meets the strong-weak balance requirement according to the evaluation results, including:

[0041] The voltage stiffness of the corresponding node is calculated according to the voltage of the node corresponding to the network equipment in the initial optimization scheme of the AC / DC hybrid network.

[0042] If the voltage stiffness of all nodes in the initial optimization scheme of the AC / DC hybrid network is greater than a first preset value, it is determined that the initial optimization scheme of the AC / DC hybrid network meets the voltage stability requirement.

[0043] The AC / DC system strength ratio index between all pairs of nodes in the initial optimization scheme of the AC / DC hybrid network is calculated.

[0044] If the AC / DC system strength ratio index between all pairs of nodes in the initial optimization scheme of the AC / DC hybrid network is greater than a second preset value, it is determined that the initial optimization scheme of the AC / DC hybrid network meets the system transient stability requirement.

[0045] If the initial optimization scheme of the AC / DC hybrid network meets both the voltage stability requirement and the system transient stability requirement, it is determined that the initial optimization scheme of the AC / DC hybrid network meets the strong-weak balance requirement.

[0046] The initial optimization scheme of the AC / DC hybrid network that meets the strong-weak balance requirement is determined as the optimal AC / DC hybrid network optimization scheme.

[0047] Further, the voltage stiffness is the ratio of the voltage modulus of the network port when the node corresponding network equipment is connected to the no-load voltage when the node corresponding network equipment is not connected.

[0048] Further, the AC / DC system strength ratio index is the ratio between the AC channel capacity and the DC channel capacity between the two nodes.

[0049] Further, the adjustment module adjusts the initial optimization scheme of the AC / DC hybrid network that does not meet the strong-weak balance requirement until the optimal AC / DC hybrid network optimization scheme that meets the strong-weak balance requirement is obtained, including:

[0050] The static reactive power compensation device or the VSC DC device is introduced into the initial optimization scheme of the AC / DC hybrid network framework which does not meet the voltage stability requirement, and the voltage stability evaluation and adjustment are performed again on the adjusted initial optimization scheme of the AC / DC hybrid network framework until the voltage stability requirement is met.

[0051] The AC line between nodes is disconnected for the initial optimization scheme of the AC / DC hybrid network framework which does not meet the system transient stability requirement, and the system transient stability evaluation and adjustment are performed again until the system transient stability requirement is met.

[0052] The initial optimization scheme of the AC / DC hybrid network framework which meets the voltage stability requirement and the system transient stability requirement after adjustment is determined as the optimal AC / DC hybrid network optimization scheme.

[0053] Further, the adjustment module introduces the static reactive power compensation device or the VSC DC device into the initial optimization scheme of the AC / DC hybrid network framework which does not meet the voltage stability requirement, and the adjustment module comprises the following steps:

[0054] The node with the voltage stiffness less than or equal to the first preset value in the initial optimization scheme of the AC / DC hybrid network framework which does not meet the voltage stability requirement is identified.

[0055] The static reactive power compensation device or the VSC DC device is connected at the node with the voltage stiffness less than or equal to the first preset value.

[0056] Further, the adjustment module disconnects the AC line between nodes for the initial optimization scheme of the AC / DC hybrid network framework which does not meet the system transient stability requirement, and the adjustment module comprises the following steps:

[0057] The node with the AC / DC system strength ratio index less than or equal to the second preset value in the initial optimization scheme of the AC / DC hybrid network framework which does not meet the system transient stability requirement is determined.

[0058] The AC line in the power transmission section between two nodes with the AC / DC system strength ratio index less than or equal to the second preset value is disconnected.

[0059] An electronic device comprises a processor and a storage device, the storage device stores a plurality of instructions, and the processor is used for reading the instructions and performing the above method.

[0060] A computer storage medium stores a plurality of instructions, and the plurality of instructions are used for performing the above method when being read.

[0061] The AC / DC hybrid network framework optimization control method and device based on strong and weak balance provided by the application have at least the following beneficial effects:

[0062] (1) Put forward the AC / DC hybrid network optimization model based on the constraints of power flow, short-circuit current, channel and converter station capacity and planning cost, ensure that the optimized network can meet the requirements of power balance and voltage stability under normal operation and fault conditions, avoid overload or voltage out of limit, optimize the power flow distribution, reduce network loss, improve power transmission efficiency, reduce operation cost, limit the short-circuit current level within the breaking capacity of circuit breakers, transformers and other equipment, avoid equipment damage, prevent short-circuit fault propagation, reduce the risk of cascading failure, especially in the case of DC system fault (such as commutation failure), which can quickly isolate the fault area, ensure that the network can still meet the operation requirements under N-1 fault or extreme scenario, maximize the avoidance of fault impact, and improve the robustness of the network system; At the same time, the economy is considered;

[0063] (2) The voltage stiffness and AC / DC system strength ratio index are used to check whether the voltage and transient stability of the optimized AC / DC hybrid network meet the engineering standards, and finally the topology structure and adjustment strategy are proposed for the scenes that do not meet the engineering stability standards, so as to realize the construction of AC / DC hybrid network considering economy, safety and stability, so that the AC system and DC system in the optimized AC / DC hybrid network meet the strong and weak balance principle;

[0064] (3) Introducing static reactive power compensation device or VSC DC device in the initial optimization scheme of AC / DC hybrid network that does not meet the voltage stability requirements can effectively suppress voltage fluctuation and improve voltage stability, further optimizing the AC / DC hybrid network;

[0065] (4) For the initial optimization scheme of AC / DC hybrid network that does not meet the system transient stability requirements, the AC line between nodes is disconnected, which can optimize the power flow distribution and further improve the system transient stability, further optimizing the AC / DC hybrid network. BRIEF DESCRIPTION OF DRAWINGS

[0066] Figure 1 The flow chart of one embodiment of the AC / DC hybrid network optimization control method based on strong and weak balance provided by the application is shown.

[0067] Figure 2 The flow chart of one embodiment of voltage stability evaluation and system transient stability evaluation in the AC / DC hybrid network optimization control method based on strong and weak balance provided by the application is shown.

[0068] Figure 3 The schematic diagram of the relationship between short-circuit ratio and voltage stiffness in the AC / DC hybrid network optimization control method based on strong and weak balance provided by the application is shown.

[0069] Figure 4The flow chart of one embodiment of adjusting the initial optimization scheme of the AC-DC hybrid network in the AC-DC hybrid network optimization control method based on strong-weak balance provided by the application.

[0070] Figure 5 The network structure schematic diagram in one application scenario of the AC-DC hybrid network optimization control method based on strong-weak balance provided by the application.

[0071] Figure 6 The optimized network structure schematic diagram in one application scenario of the AC-DC hybrid network optimization control method based on strong-weak balance provided by the application.

[0072] Figure 7 The structure schematic diagram of one embodiment of the AC-DC hybrid network optimization control device based on strong-weak balance provided by the application. DETAILED DESCRIPTION

[0073] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in combination with the drawings of the specification and specific embodiments.

[0074] REFERENCE Figure 1 In some embodiments, an AC-DC hybrid network optimization control method based on strong-weak balance is provided, comprising:

[0075] S1, constructing an AC-DC hybrid network optimization model considering the flow constraints, short-circuit current constraints, channel and converter station capacity constraints and planning costs;

[0076] S2, based on the AC-DC hybrid network optimization model, optimizing the current AC-DC hybrid network structure to obtain an initial optimization scheme of the AC-DC hybrid network;

[0077] S3, evaluating the voltage stability and the system transient stability of the initial optimization scheme of the AC-DC hybrid network, and judging whether the initial optimization scheme of the AC-DC hybrid network meets the strong-weak balance requirement according to the evaluation results;

[0078] S4, adjusting the initial optimization scheme of the AC-DC hybrid network which does not meet the strong-weak balance requirement until the optimal AC-DC hybrid network optimization scheme meeting the strong-weak balance requirement is obtained.

[0079] Specifically, in step S1, the AC-DC hybrid network optimization model includes flow constraint conditions, short-circuit current constraint conditions, channel and converter station capacity constraints, and an objective function of minimizing the planning cost.

[0080] With the increasing of new energy installed capacity and load in the national power grid, the adoption of the new AC scheme in the provincial AC-DC hybrid power grid can effectively share the transmission load of the existing line, thereby relieving the overload pressure of the line and improving the new energy consumption capacity. For the new DC scheme, due to the power flexible regulation characteristics of the DC transmission system, the AC-DC hybrid transmission section can realize power optimization distribution through the coordinated control strategy. After the embedded DC is introduced, the power flow constraint condition of each transmission section in the grid can meet the load supply demand and the power generation consumption demand under the new energy scenario in the steady state, which can be described as:

[0081] (1)

[0082] (2)

[0083] wherein, is the total capacity of the new DC line between the i th node and the j th node, is the total capacity of the new AC line between the i th node and the j th node, is the existing total transmission capacity between the i th node and the j th node, represents the total capacity of the AC line in the AC line to DC line scheme between the i th node and the j th node in the topology optimization process, r is the number of nodes in the AC-DC hybrid power grid, P G and P L are the power generation consumption demand and the node load supply demand, respectively, and G represents the set of power output nodes in the sending end power grid, and L represents the set of nodes that accept power supply in the receiving end power grid.

[0084] In addition, the AC-DC hybrid power grid should also have a certain fault risk resistance ability. In the AC-DC hybrid power grid, after the N-1 fault of the AC or DC line, the steady-state power flow of the fault line will be transferred to the remaining AC lines in the section, which will bring a great impact on the AC line, while the DC line will not participate in the power flow redistribution due to its controllable power characteristics. Therefore, in the process of planning the AC-DC hybrid power grid, the power flow constraint under the N-1 fault is also an important factor to be considered. The N-1 impact resistance strength index S ac,dc_ij of the i th node and the j th node in the system can accurately describe the resistance ability of the AC line to the power flow transfer impact of the fault line under the planning scheme, and provide a theoretical basis for the safety assessment of the power grid. Therefore, the power flow constraint condition also includes:

[0085] (3)

[0086] wherein, S ac,dc_ij is the N-1 impact resistance strength index, is the total maximum transmission capacity of the AC transmission line in the AC-DC hybrid power grid, is the sum of steady-state transmission power of all AC lines in the AC / DC hybrid grid under normal operation state, is the transmission power of the kth DC line between the ith node and the jth node.

[0087] Due to the introduction of DC, the electrical distance between nodes in the AC / DC hybrid grid is larger than that in the AC grid, which will reduce the short-circuit current of the nodes. The AC grid has dense lines and large transmission capacity, so the risk of exceeding the short-circuit current is high. Once the short-circuit current exceeds the limit, the heat and electric power generated will damage the performance of the equipment, cause voltage sag, destroy system stability, and even cause large-scale power outages. Therefore, the short-circuit current is one of the key factors restricting the development of the grid scale. Each node needs to meet the maximum allowed short-circuit current limit during planning. Considering the different structures of the power grid, equipment characteristics, and operation modes, a certain safety margin of short-circuit current needs to be ensured. Therefore, the short-circuit current constraint condition can be expressed as:

[0088] ; (4)

[0089] ; (5)

[0090] wherein, is the maximum allowed short-circuit current of the ith node in the AC / DC hybrid grid, is the actual short-circuit current peak value of the ith node in the AC / DC hybrid grid, ii is the self-impedance value of the ith node, i is the short-circuit current margin value of the ith node, is the minimum required short-circuit current margin value of the ith node.

[0091] Further, the channel resource constraint is also a key issue that needs to be considered during the topology planning of the AC / DC hybrid grid. Since the existing AC grid has developed relatively maturely, the transmission lines are dense, and the resources such as land and pipeline for building transmission channels are close to saturation, which brings challenges to the expansion of transmission channels. Considering the capacity limitation of the converter station unit, in order to ensure power stability and efficient transmission, it is necessary to reasonably utilize channel resources and meet the channel transmission power constraint to ensure that the processing capacity of the converter station covers the total capacity of the lines. The following are the channel and converter station capacity constraint expressions:

[0092] ; (6)

[0093] ; (7)

[0094] wherein, is the maximum transmission power limit of the channel between the ith node and the jth node, dc_ij is the number of DC converter stations in the channel between the ith node and the jth node, For the capacity limit of a single converter station, For the power transmission between the i-th node and the j-th node via the k-th DC line, m represents the number of DC lines, For the total capacity of the newly added DC lines in the channel between the i-th node and the j-th node, For the total capacity of the newly added AC lines in the channel between the i-th node and the j-th node, represents the total capacity of the AC lines in the AC-to-DC scheme between the i-th node and the j-th node in the topology optimization process, For the existing total transmission capacity of the channel between the i-th node and the j-th node.

[0095] The above power flow constraints, short-circuit current constraints, channel and converter station capacity constraints limit the capacity and location of AC and DC systems in the AC / DC hybrid network. Under limited channel resources, the introduction of DC may use the AC-to-DC scheme, and at this time, due to the lack of AC transmission margin capacity in the network transmission section, the anti-power flow transfer impact ability under N-1 fault is weak. To improve the fault resistance of the power grid, some nodes may be accompanied by AC strengthening. The following will construct a planning cost function by comprehensively considering the cost conditions of different schemes:

[0096] ; (8)

[0097] where L ij is the line length, c dc_ij is the unit (MW·km) cost of the newly added DC scheme between the i-th node and the j-th node, c ac_ij is the unit cost of the newly added AC scheme between the i-th node and the j-th node, c ac-dc_ij is the unit cost of the AC-to-DC scheme between the i-th node and the j-th node, c 0_ij is the unit cost of the DC converter station, C total_ij is the planning cost of the AC / DC channel between the i-th node and the j-th node, which includes construction cost, operation and maintenance cost, depreciation cost, etc. N dc_ij is the number of DC converter stations in the channel between the i-th node and the j-th node, is the total capacity of the newly added AC lines between the i-th node and the j-th node in the optimization process, is the total capacity of the AC lines in the AC-to-DC scheme, is the total capacity of the newly added DC lines in the channel between the i-th node and the j-th node.

[0098] Based on the above power flow constraints, short-circuit current constraints, channel and converter station capacity constraints, an AC / DC hybrid network optimization model is constructed with the objective of minimizing the planning cost:

[0099] ;

[0100] ; (9)

[0101] Further, in step S2, based on the AC / DC hybrid power grid architecture optimization model, the current AC / DC hybrid power grid architecture structure is optimized to obtain an initial optimization scheme of the AC / DC hybrid power grid architecture, including:

[0102] At least one of the following operations is performed on the current AC / DC hybrid power grid architecture structure: adding a DC line, adding an AC line, and changing an AC line to a DC line, to obtain a candidate scheme. Based on the candidate scheme, an optimization algorithm is used to calculate an initial optimization scheme of the AC / DC hybrid power grid architecture that satisfies the power flow constraint condition, the short-circuit current constraint condition, the channel and converter station capacity constraint condition, and the minimum planning cost.

[0103] The optimization algorithm can include a particle algorithm, a genetic algorithm, etc.

[0104] For example, using a particle algorithm, the candidate solution of the candidate scheme is taken as a particle, the candidate solution is the scheme after performing at least one of the following operations on the current AC / DC hybrid power grid architecture structure: adding a DC line, adding an AC line, and changing an AC line to a DC line, the particle swarm is initialized, the fitness of each particle is calculated, the individual optimum and global optimum are updated according to the fitness of the particle, the speed and position of the ion are updated, until the stop condition is met, and the global optimum solution is taken as the initial optimization scheme of the AC / DC hybrid power grid architecture.

[0105] Further, referring to Figure 2 In step S3, the voltage stability and system transient stability of the initial optimization scheme of the AC / DC hybrid power grid architecture are evaluated, and it is determined whether the initial optimization scheme of the AC / DC hybrid power grid architecture meets the strong-weak balance requirement according to the evaluation results, including:

[0106] S31, according to the voltage of the node corresponding to the network equipment in the initial optimization scheme of the AC / DC hybrid power grid architecture, the voltage stiffness of the corresponding node is calculated;

[0107] S32, if the voltage stiffness of all nodes in the initial optimization scheme of the AC / DC hybrid power grid architecture is greater than a first preset value, it is determined that the initial optimization scheme of the AC / DC hybrid power grid architecture meets the voltage stability requirement;

[0108] S33, according to the AC channel capacity and DC channel capacity between all pairs of nodes in the initial optimization scheme of the AC / DC hybrid power grid architecture, the AC / DC system strength ratio index is calculated;

[0109] S34. If the AC / DC system strength ratio index of all pairs of nodes in the initial optimization scheme of the AC / DC hybrid network is greater than the second preset value, then the initial optimization scheme of the AC / DC hybrid network is determined to meet the system transient stability requirements.

[0110] S35. If the initial optimization scheme of the AC / DC hybrid network simultaneously meets the voltage stability requirement and the system transient stability requirement, then it is determined that the initial optimization scheme of the AC / DC hybrid network meets the strong and weak balance requirement.

[0111] S36. The initial optimization scheme of the AC / DC hybrid network structure that meets the requirements of strong and weak balance is determined as the optimal optimization scheme of the AC / DC hybrid network structure.

[0112] Specifically, in step S31, the voltage stiffness is the ratio of the voltage magnitude of the network port when the corresponding network access device of the node is connected to the no-load voltage when the corresponding network access device of the node is not connected.

[0113] Compared to an all-AC network, the introduction of DC weakens the AC connections between nodes, reduces the AC system's ability to support the voltage and power of the hybrid network, and decreases the system's voltage and transient stability. The following section will examine whether the voltage and transient stability of the AC / DC hybrid network under the initial optimized scheme meet the engineering requirements.

[0114] The first step is to verify the voltage stability of the power grid, which primarily depends on the strength of the AC system. Voltage stability can be verified using a voltage stiffness index, which measures the strength of the AC system and is also applicable to AC / DC hybrid power grids. This index defines the voltage support strength at any point in the power grid as the ability to maintain the voltage modulus at the connection point close to the no-load voltage at that point. The voltage stiffness of a node can be calculated using the following formula:

[0115] (10)

[0116] Among them, K vtg Let λ be the voltage stiffness of the node. SCR U represents the short-circuit ratio of the network-connected device corresponding to the node. sys U represents the voltage modulus value on the network port of the device corresponding to the node. sys0 Voltage stiffness is the unloaded voltage at any point when the corresponding network-connected equipment is not connected to the power grid.

[0117] Based on the relationship between short-circuit ratio and voltage stiffness, such as Figure 3 As shown, it can be seen that when λ SCR >>1, U sys ≈U N When λ SCR When =5, U sys =0.98U N When λSCR =3, U sys =0.95U N ; when λ SCR =1, U sys =0.71U N ; therefore, it can be considered that when the voltage stiffness is greater than 0.95, the system voltage support capability is strong, which meets the voltage stability requirement. Therefore, the first preset value can be 0.95.

[0118] The voltage stiffness of all nodes in the initial optimization scheme of the AC-DC hybrid network is globally scanned, and if the voltage stiffness of all nodes in the initial optimization scheme of the AC-DC hybrid network is greater than the first preset value, it is determined that the initial optimization scheme of the AC-DC hybrid network meets the voltage stability requirement.

[0119] Further, in step S33, the AC-DC system strength ratio index is the ratio between the AC channel capacity and the DC channel capacity between two nodes.

[0120] Specifically, for the case of multiple DC simultaneous commutation failures or multiple line lockouts caused by serious short-circuit faults of the receiving end power grid, etc., whether the balance of the sending and receiving end system power can be maintained is the key to the transient stability. In order to accurately represent the system transient stability, the strength of the AC system and the DC system needs to be compared, and only when the AC-DC system strength balance is met, the power angle and frequency instability of the entire system can be avoided. Therefore, the AC-DC system strength ratio index Q ac,dc_ij Perform system transient stability evaluation:

[0121] ; (11)

[0122] wherein, represents the AC channel capacity between the i th node and the j th node, represents the DC channel capacity between the i th node and the j th node, Q ac,dc_ij represents the AC-DC system strength ratio index.

[0123] In some embodiments, when Q ac,dc_ij >0.5, the transient stability of the network is considered to meet the requirements. When Q ac,dc_ij <0.5, it is considered that the system transient stability is insufficient to ensure the network operation safety, i.e. the second preset value can be 0.5.

[0124] Specifically, in step S35, if the initial optimization scheme of the AC-DC hybrid network meets both the stability requirement and the system transient stability requirement, the AC system and the DC system in the initial optimization scheme of the AC-DC hybrid network are in strength balance.

[0125] Further, referring to Figure 4 In step S4, the initial optimization scheme of the AC / DC hybrid network framework that does not satisfy the strong-weak balance is adjusted until an optimal AC / DC hybrid network framework optimization scheme that satisfies the strong-weak balance requirement is obtained, including:

[0126] S41, a static reactive power compensation device or a VSC DC device is introduced to the initial optimization scheme of the AC / DC hybrid network framework that does not satisfy the voltage stability requirement, and the voltage stability of the adjusted initial optimization scheme of the AC / DC hybrid network framework is evaluated and adjusted again until the voltage stability requirement is satisfied.

[0127] S42, for the initial optimization scheme of the AC / DC hybrid network framework that does not satisfy the system transient stability requirement, the AC line between nodes is disconnected, and the system transient stability is evaluated and adjusted again until the system transient stability requirement is satisfied.

[0128] S43, the initial optimization scheme of the AC / DC hybrid network framework that satisfies the voltage stability requirement and the system transient stability requirement after adjustment is determined as the optimal AC / DC hybrid network framework optimization scheme.

[0129] In the above voltage stiffness index-based network framework voltage stability check, if the voltage stiffness index is higher than 0.95, it is considered that the voltage support capability is strong enough to meet the engineering requirements, otherwise the planning scheme is not feasible, and the AC line capacity can be appropriately increased or the SVC / VSC DC device can be installed to provide voltage support for the network framework and improve the voltage stability of the power grid.

[0130] In the above AC / DC system strength ratio index-based network framework transmission section transient stability check, if Q ac,dc_ij >0.5, the network framework strength is large enough to satisfy the AC / DC strong-weak balance principle and meet the engineering requirements; if Q ac,dc_ij <0.5, the transient stability is insufficient, and the power angle difference between the two ends of the line may diverge and the power angle instability may occur when the fault occurs. At this time, the AC line between the nodes of the section can be disconnected to realize asynchronous operation in different regions.

[0131] Further, in step S41, the static reactive power compensation device or the VSC DC device is introduced to the initial optimization scheme of the AC / DC hybrid network framework that does not satisfy the voltage stability requirement, including:

[0132] Identifying the nodes in the initial optimization scheme of the AC / DC hybrid network framework that do not satisfy the voltage stability requirement and whose voltage stiffness is less than or equal to a first preset value.

[0133] Connecting a static reactive power compensation device or a VSC DC device to the nodes whose voltage stiffness is less than or equal to the first preset value.

[0134] Furthermore, in step S42, for the initial optimization scheme of the AC / DC hybrid network that does not meet the system transient stability requirements, the AC lines between nodes are disconnected, including:

[0135] Identify nodes in the initial optimization scheme of AC / DC hybrid network that do not meet the system transient stability requirements, where the AC / DC system strength ratio index is less than or equal to the second preset value.

[0136] The AC lines in the transmission sections between two nodes of the AC / DC system whose strength ratio index is less than or equal to the second preset value are disconnected.

[0137] If the adjusted initial optimization scheme of the AC / DC hybrid network simultaneously meets the stability requirements and the system transient stability requirements, then the AC system and DC system in the adjusted initial optimization scheme of the AC / DC hybrid network are in a strong-weak balance.

[0138] The methods provided in the above embodiments will be further explained through specific application scenarios below.

[0139] Using a four-zone AC internetwork as an example, its original AC / DC hybrid internetwork structure is shown in the attached figure. Figure 5 As shown. The AC / DC hybrid grid structure includes two sending-end grids and two receiving-end grids, namely sending-end grid 1, sending-end grid 2, receiving-end grid 1, and receiving-end grid 2. Sending-end grid 1 includes synchronizing machines 1, 2, and 3; sending-end grid 2 includes synchronizing machines 4, 5, and 6; receiving-end grid 1 includes load 1 and load 2; and receiving-end grid 2 includes load 3 and load 4. The power generation of sending-end grid 1 and sending-end grid 2 are 532MW and 2840MW, respectively, and the load power demand of receiving-end grid 1 and receiving-end grid 2 are 1466MW and 2580MW, respectively. The key transmission sections between each zone are AC interconnections. Sending-end grid 1 and receiving-end grid 1 are interconnected through channels 1 and 2, and sending-end grid 2 and receiving-end grid 2 are interconnected through channels 3 and 4. Labels 1-30 indicate node numbers. Using the AC / DC hybrid grid optimization model provided in this embodiment, the AC / DC hybrid grid structure is simulated and analyzed to obtain the initial optimization scheme of the AC / DC hybrid grid as shown in the attached figure. Figure 6 As shown, two DC lines, line A and line B, were added to channel 3. The changes in power flow parameters of the AC / DC hybrid grid structure before and after optimization under steady-state and N-1 fault conditions are shown in Table 1. The short-circuit current margins of nodes 7 and 8 are 0.78% and 0.44% respectively before and after optimization. Regarding stability, the voltage stiffness of the grid nodes is concentrated between 0.96 and 0.97, all higher than 0.95. Furthermore, the AC / DC system strength ratio of the interconnection channels between the sending and receiving ends and the key transmission sections of the system are all above 0.92, greater than 0.5, meeting the AC / DC strength balance standard, thus verifying the good adaptability of the AC / DC hybrid grid optimization model.

[0140] Table 1 Power flow parameters of the grid structure before and after topology optimization under steady state and N-1 fault state

[0141]

[0142] Reference Figure 7 In some embodiments, a strong-weak balance-based AC / DC hybrid grid optimization control device is provided, comprising:

[0143] A model construction module 201 is configured to construct an AC / DC hybrid grid optimization model considering power flow constraints, short-circuit current constraints, channel and converter station capacity constraints, and planning costs.

[0144] An initial optimization module 202 is configured to optimize a current AC / DC hybrid grid structure based on the AC / DC hybrid grid optimization model to obtain an initial optimization scheme of the AC / DC hybrid grid.

[0145] An evaluation module 203 is configured to evaluate the voltage stability and system transient stability of the initial optimization scheme of the AC / DC hybrid grid, and determine whether the initial optimization scheme of the AC / DC hybrid grid meets the strong-weak balance requirement based on the evaluation results.

[0146] An adjustment model 204 is configured to adjust the initial optimization scheme of the AC / DC hybrid grid that does not meet the strong-weak balance requirement until an optimal AC / DC hybrid grid optimization scheme that meets the strong-weak balance requirement is obtained.

[0147] Further, the AC / DC hybrid grid optimization model includes power flow constraint conditions, short-circuit current constraint conditions, channel and converter station capacity constraint conditions, and an objective function with the minimum planning cost.

[0148] Further, the initial optimization module 202 optimizes the current AC / DC hybrid grid structure based on the AC / DC hybrid grid optimization model to obtain an initial optimization scheme of the AC / DC hybrid grid, including:

[0149] Performing at least one of adding a DC line, adding an AC line, and converting an AC line to a DC line on the current AC / DC hybrid grid structure to obtain a candidate scheme, and calculating an initial optimization scheme of the AC / DC hybrid grid that meets the power flow constraint conditions, short-circuit current constraint conditions, channel and converter station capacity constraint conditions, and minimum planning cost based on the candidate scheme using an optimization algorithm.

[0150] Further, the evaluation module 203 evaluates the voltage stability and system transient stability of the initial optimization scheme of the AC / DC hybrid grid, and determines whether the initial optimization scheme of the AC / DC hybrid grid meets the strong-weak balance requirement based on the evaluation results, including:

[0151] According to the voltage of the node corresponding to the grid-connected equipment in the initial optimization scheme of the AC-DC hybrid power grid, the voltage stiffness of the corresponding node is calculated;

[0152] If the voltage stiffness of all nodes in the initial optimization scheme of the AC-DC hybrid power grid is greater than a first preset value, it is determined that the initial optimization scheme of the AC-DC hybrid power grid meets the voltage stability requirement;

[0153] According to the AC channel capacity and DC channel capacity between all pairs of nodes in the initial optimization scheme of the AC-DC hybrid power grid, the AC-DC system strength ratio index is calculated;

[0154] If the AC-DC system strength ratio index of all pairs of nodes in the initial optimization scheme of the AC-DC hybrid power grid is greater than a second preset value, it is determined that the initial optimization scheme of the AC-DC hybrid power grid meets the system transient stability requirement;

[0155] If the initial optimization scheme of the AC-DC hybrid power grid meets both the voltage stability requirement and the system transient stability requirement, it is determined that the initial optimization scheme of the AC-DC hybrid power grid meets the strong-weak balance requirement;

[0156] The initial optimization scheme of the AC-DC hybrid power grid that meets the strong-weak balance requirement is determined as the optimal AC-DC hybrid power grid optimization scheme.

[0157] Further, the voltage stiffness is the ratio of the voltage modulus value of the network port when the node corresponding grid-connected equipment is accessed to the no-load voltage when the node corresponding grid-connected equipment is not accessed.

[0158] Further, the AC-DC system strength ratio index is the ratio between the AC channel capacity and the DC channel capacity between the two nodes.

[0159] Further, the adjustment module 204 adjusts the initial optimization scheme of the AC-DC hybrid power grid that does not meet the strong-weak balance until the optimal AC-DC hybrid power grid optimization scheme that meets the strong-weak balance requirement is obtained, including:

[0160] For the initial optimization scheme of the AC-DC hybrid power grid that does not meet the voltage stability requirement, a static reactive power compensation device or a VSC DC device is introduced, and the adjusted initial optimization scheme of the AC-DC hybrid power grid is evaluated and adjusted again for voltage stability until the voltage stability requirement is met;

[0161] For the initial optimization scheme of the AC-DC hybrid power grid that does not meet the system transient stability requirement, the AC line between the nodes is disconnected, and the system transient stability is evaluated and adjusted again until the system transient stability requirement is met;

[0162] The initial optimization scheme of the AC / DC hybrid network satisfying the voltage stability requirement and the system transient stability requirement is determined as the optimal AC / DC hybrid network optimization scheme.

[0163] Further, the adjustment module 204 introduces a static reactive power compensation device or a VSC DC device to the initial optimization scheme of the AC / DC hybrid network not satisfying the voltage stability requirement, including:

[0164] Identifying a node in the initial optimization scheme of the AC / DC hybrid network not satisfying the voltage stability requirement, whose voltage stiffness is less than or equal to a first preset value.

[0165] Connecting the static reactive power compensation device or the VSC DC device to the node whose voltage stiffness is less than or equal to the first preset value.

[0166] Further, the adjustment module 204 opens the AC line between nodes for the initial optimization scheme of the AC / DC hybrid network not satisfying the system transient stability requirement, including:

[0167] Determining a node in the initial optimization scheme of the AC / DC hybrid network not satisfying the system transient stability requirement, whose AC / DC system strength ratio index is less than or equal to a second preset value.

[0168] Opening the AC line in the power transmission section between two nodes whose AC / DC system strength ratio index is less than or equal to the second preset value.

[0169] In some embodiments, an electronic device is also provided, including a processor and a storage device, the storage device storing a plurality of instructions, and the processor being configured to read the instructions and perform the above method.

[0170] In some embodiments, a computer storage medium is also provided, storing a plurality of instructions, and the plurality of instructions being configured to perform the above method when read.

[0171] The AC / DC hybrid network optimization control method and device based on the strength-weakness balance provided by the above embodiments at least have the following beneficial effects:

[0172] (1) Put forward the AC / DC hybrid network architecture optimization model based on the constraints of power flow, short-circuit current, channel and converter station capacity, and planning cost, to ensure that the optimized network architecture can meet the requirements of power balance and voltage stability under normal operation and fault conditions, avoid overload or voltage out-of-limit, optimize power flow distribution, reduce network loss, improve power transmission efficiency, reduce operation cost, limit the short-circuit current level within the breaking capacity of circuit breakers, transformers and other equipment, avoid equipment damage, prevent short-circuit fault propagation, reduce the risk of cascading failure, especially in the case of DC system fault (such as commutation failure) to quickly isolate the fault area, ensure that the network architecture can still meet the operation requirements under N-1 fault or extreme scenarios, maximize the avoidance of fault impact, and improve the robustness of the network architecture system; At the same time, economic efficiency is considered;

[0173] (2) The voltage stiffness and AC / DC system strength ratio indexes are used to check whether the voltage and transient stability of the optimized AC / DC hybrid network architecture meet the engineering standards, and finally the topology structure and adjustment strategy are proposed for the scenes that do not meet the engineering stability standards, to realize the construction of AC / DC hybrid network architecture considering economic efficiency, safety and stability, and meet the strong and weak balance principle;

[0174] (3) Introducing static reactive power compensation devices or VSC DC devices in the initial optimization scheme of the AC / DC hybrid network architecture that does not meet the voltage stability requirements can effectively suppress voltage fluctuations and improve voltage stability, further optimizing the AC / DC hybrid network architecture;

[0175] (4) For the initial optimization scheme of the AC / DC hybrid network architecture that does not meet the system transient stability requirements, breaking the AC lines between nodes can optimize the power flow distribution and further improve the system transient stability, further optimizing the AC / DC hybrid network architecture.

[0176] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to the embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application. Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for optimal control of AC / DC hybrid power grid based on strong-weak balance, characterized in that, The method comprises the following steps: An AC / DC hybrid grid optimization model considering the constraints of tidal flow, short-circuit current, channel and converter station capacity, and planning cost is constructed; Based on the AC / DC hybrid grid optimization model, the current AC / DC hybrid grid structure is optimized to obtain an initial optimization scheme of the AC / DC hybrid grid: at least one of the operations of adding a DC line, adding an AC line, and converting an AC line into a DC line is performed on the current AC / DC hybrid grid structure to obtain a candidate scheme, and an optimization algorithm is used to calculate the initial optimization scheme of the AC / DC hybrid grid that meets the constraints of tidal flow, short-circuit current, channel and converter station capacity, and has the minimum planning cost based on the candidate scheme; The voltage stability and system transient stability of the initial optimization scheme of the AC / DC hybrid grid are evaluated, and whether the initial optimization scheme of the AC / DC hybrid grid meets the strong-weak balance requirement is determined according to the evaluation results; The initial optimization scheme of the AC / DC hybrid grid that does not meet the strong-weak balance requirement is adjusted until an optimal optimization scheme of the AC / DC hybrid grid that meets the strong-weak balance requirement is obtained; The AC / DC hybrid grid optimization model is as follows: ; where r is the number of nodes in the AC / DC hybrid power grid, C total_ij is the AC / DC planning cost of the channel between the i-th node and the j-th node, is the total capacity of the new DC line of the channel between the i-th node and the j-th node, is the total capacity of the new AC line of the channel between the i-th node and the j-th node, is the total existing transmission capacity of the channel between the i-th node and the j-th node, represents the total capacity of the AC line in the scheme of converting the AC line to the DC line between the i-th node and the j-th node in the topology optimization process, PG and PL are the power generation and consumption demand and the node load supply demand, G represents a set of power output nodes in the sending end power grid, and L represents a set of nodes that accept power supply in the receiving end power grid, is the total maximum transmission capacity of the AC transmission line in the AC / DC hybrid power grid, is the total steady-state transmission power of all AC lines in the AC / DC hybrid power grid in the normal operation state, is the transmission power of the k-th DC line between the i-th node and the j-th node, is the maximum allowable short-circuit current of the i-th node in the AC / DC hybrid power grid, is the actual peak short-circuit current of the i-th node in the AC / DC hybrid power grid, is the short-circuit current margin value of the i-th node, is the minimum required short-circuit current margin value of the i-th node, is the maximum transmission power limit of the channel between the i-th node and the j-th node, is the number of DC converter stations in the channel between the i-th node and the j-th node, is the capacity limit of a single converter station, is the transmission power of the k-th DC line between the i-th node and the j-th node, and m represents the number of DC lines.

2. The method of claim 1, wherein, The voltage stability and system transient stability of the initial optimization scheme of the AC / DC hybrid grid are evaluated, and whether the initial optimization scheme of the AC / DC hybrid grid meets the strong-weak balance requirement is determined according to the evaluation results, which comprises: The voltage stiffness of the corresponding node is calculated according to the voltage of the node corresponding to the network access equipment in the initial optimization scheme of the AC / DC hybrid grid; If the voltage stiffness of all nodes in the initial optimization scheme of the AC / DC hybrid grid is greater than a first preset value, it is determined that the initial optimization scheme of the AC / DC hybrid grid meets the voltage stability requirement; The AC / DC system strength ratio index of all pairs of nodes in the initial optimization scheme of the AC / DC hybrid grid is calculated according to the AC channel capacity and DC channel capacity between the nodes; If the AC / DC system strength ratio index of all pairs of nodes in the initial optimization scheme of the AC / DC hybrid grid is greater than a second preset value, it is determined that the initial optimization scheme of the AC / DC hybrid grid meets the system transient stability requirement; If the initial optimization scheme of the AC / DC hybrid grid meets both the voltage stability requirement and the system transient stability requirement, it is determined that the initial optimization scheme of the AC / DC hybrid grid meets the strong-weak balance requirement; The initial optimization scheme of the AC / DC hybrid grid that meets the strong-weak balance requirement is determined as the optimal optimization scheme of the AC / DC hybrid grid.

3. The method of claim 2, wherein, The voltage stiffness is the ratio of the voltage modulus of the network port when the node corresponding network access equipment is accessed to the no-load voltage when the node corresponding network access equipment is not accessed.

4. The method of claim 2, wherein, The AC / DC system strength ratio index is the ratio between the AC channel capacity and the DC channel capacity between the nodes.

5. The method of claim 2, wherein, The initial optimization scheme of the AC / DC hybrid grid that does not meet the strong-weak balance is adjusted until an optimal optimization scheme of the AC / DC hybrid grid that meets the strong-weak balance requirement is obtained, which comprises: introducing a static reactive power compensation device or a VSC DC device to an initial optimization scheme of the AC / DC hybrid network that does not meet the voltage stability requirement, performing voltage stability evaluation and adjustment on the adjusted initial optimization scheme of the AC / DC hybrid network, and repeating the above until the voltage stability requirement is met; opening the AC line between nodes for the initial optimization scheme of the AC / DC hybrid network that does not meet the system transient stability requirement, and performing system transient stability evaluation and adjustment again until the system transient stability requirement is met; determining the initial optimization scheme of the AC / DC hybrid network that meets both the voltage stability requirement and the system transient stability requirement as the optimal AC / DC hybrid network optimization scheme.

6. The method of claim 5, wherein, introducing a static reactive power compensation device or a VSC DC device to an initial optimization scheme of the AC / DC hybrid network that does not meet the voltage stability requirement, including: identifying a node in the initial optimization scheme of the AC / DC hybrid network that does not meet the voltage stability requirement and whose voltage stiffness is less than or equal to a first preset value; connecting a static reactive power compensation device or a VSC DC device to the node whose voltage stiffness is less than or equal to the first preset value.

7. The method of claim 5, wherein, opening the AC line between nodes for the initial optimization scheme of the AC / DC hybrid network that does not meet the system transient stability requirement, including: determining a node in the initial optimization scheme of the AC / DC hybrid network that does not meet the system transient stability requirement and whose AC / DC system strength ratio index is less than or equal to a second preset value; opening the AC line in the power transmission section between the two nodes whose AC / DC system strength ratio index is less than or equal to the second preset value.

8. A device for optimal control of AC / DC hybrid network architecture based on strong-weak balance, characterized in that, including: a model construction module configured to construct an AC / DC hybrid network optimization model considering power flow constraints, short-circuit current constraints, channel and converter station capacity constraints, and planning costs; an initial optimization module configured to optimize a current AC / DC hybrid network structure based on the AC / DC hybrid network optimization model to obtain an initial optimization scheme of the AC / DC hybrid network, perform at least one of adding a DC line, adding an AC line, and converting an AC line to a DC line on the current AC / DC hybrid network structure to obtain a candidate scheme, and calculate the initial optimization scheme of the AC / DC hybrid network that meets the power flow constraints, the short-circuit current constraints, the channel and converter station capacity constraints, and the minimum planning cost based on the candidate scheme using an optimization algorithm; an evaluation module configured to perform voltage stability evaluation and system transient stability evaluation on the initial optimization scheme of the AC / DC hybrid network, and determine whether the initial optimization scheme of the AC / DC hybrid network meets the strong-weak balance requirement according to the evaluation results; an adjustment model configured to adjust the initial optimization scheme of the AC / DC hybrid network that does not meet the strong-weak balance requirement until an optimal AC / DC hybrid network optimization scheme that meets the strong-weak balance requirement is obtained; the AC / DC hybrid network optimization model is as follows: ; where r is the number of nodes in the AC / DC hybrid power grid, C total_ij is the AC / DC planning cost of the channel between the i th node and the j th node, is the total capacity of the new DC line of the channel between the i th node and the j th node, is the total capacity of the new AC line of the channel between the i th node and the j th node, is the total existing transmission capacity of the channel between the i th node and the j th node, represents the total capacity of the AC line in the scheme of converting the AC line to the DC line between the i th node and the j th node in the topology optimization process, PG and PL are the power generation and consumption demand and the node load supply demand, G represents a set of power output nodes in the sending end power grid, and L represents a set of nodes that accept power supply in the receiving end power grid, is the total maximum transmission capacity of the AC transmission line in the AC / DC hybrid power grid, is the total steady-state transmission power of all AC lines in the AC / DC hybrid power grid in the normal operation state, is the transmission power of the k th DC line between the i th node and the j th node, is the maximum allowable short-circuit current of the i th node in the AC / DC hybrid power grid, is the actual short-circuit current peak value of the i th node in the AC / DC hybrid power grid, is the short-circuit current margin value of the i th node, is the minimum required short-circuit current margin value of the i th node, is the maximum transmission power limit of the channel between the i th node and the j th node, is the number of DC converter stations in the channel between the i th node and the j th node, is the capacity limit of a single converter station, is the transmission power of the k th DC line between the i th node and the j th node, and m represents the number of DC lines.

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