A single-thread and multi-thread power flow method for integrated transmission and distribution networks

Abstract

The application relates to a single-thread and multi-thread power flow method of a comprehensive power transmission and distribution network, and the method comprises the following steps: S1, a mathematical model of controllable energy is established to obtain an internal current source of an electronic interface distributed energy generator; S2, a backward scanning subroutine is constructed based on the internal current source, and a forward scanning subroutine is constructed; S3, the backward scanning subroutine and the forward scanning subroutine are called to perform single-thread or multi-thread power flow calculation of the comprehensive power transmission and distribution network until a convergence condition is met. Compared with the prior art, the application has the advantages of reducing the number of single-thread iterations and the like.

Description

Technical Field

[0001] This invention relates to the field of power flow calculation in distribution networks, and in particular to a single-threaded and multi-threaded power flow method for integrated transmission and distribution networks. Background Technology

[0002] Against the backdrop of the accelerated construction of new power systems, the integrated transmission and distribution network, as the core carrier of energy transmission and distribution, is experiencing a significant increase in operational complexity due to the high proportion of distributed generation and enhanced interaction among diverse loads. This places higher demands on the accuracy and efficiency of power flow calculation. As a fundamental tool for power grid planning, design, operation scheduling, and security analysis, the computational performance of power flow calculation directly affects the scientific nature and timeliness of power grid decisions.

[0003] Traditional power distribution methods suffer from several drawbacks in terms of computational efficiency. Their single-path, serial approach requires solving equations sequentially, leading to a geometrical increase in computational speed with the size of large-scale power grids. Regarding convergence, they are sensitive to grid topology, with numerous nonlinear components causing matrix condition number degradation and necessitating repeated parameter adjustments, resulting in poor convergence stability. In terms of resource utilization, the single-threaded approach cannot leverage the advantages of multi-core hardware, leading to wasted computing power. Finally, in terms of scenario adaptability, changes in grid topology require a complete system recalculation, lacking local incremental update capabilities and failing to meet the real-time response requirements of dynamic power grids. Summary of the Invention

[0004] The purpose of this invention is to adapt to different scenarios, fully leverage the accuracy advantage of single-threaded methods in small and medium-sized power grids, and overcome the computational bottleneck of large-scale power grids with multi-threaded methods, so as to provide strong technical support for the safe and stable operation of integrated power transmission and distribution networks, optimized scheduling decisions, and rapid fault diagnosis.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A single-threaded and multi-threaded power flow method for integrated power transmission and distribution networks, comprising the following steps:

[0007] A mathematical model of controllable energy is established to obtain the internal current source of the electronic interface distributed energy generator;

[0008] A backward scanning subroutine is constructed based on an internal current source, and a forward scanning subroutine is also constructed.

[0009] The backward scan subroutine and the forward scan subroutine are called to perform single-threaded or multi-threaded power flow calculations for the integrated power transmission and distribution network until the convergence condition is met.

[0010] Furthermore, the internal current source of the electronic interface distributed energy generator is:

[0011] ;

[0012] in, This indicates the internal current source of the electronic interface distributed energy generator. Let be the total three-phase complex power at node i. For phase, These represent the phases of a, b, and c, respectively. Indicates the phase at node i The conjugate of the complex number of voltage. , and Let represent the conjugate complex numbers of the voltages at phases a, b, and c at node i, respectively. This represents the p-phase self-admittance of the electronic interface distributed energy generator at node i. This represents the capacitive coupling current source between phase p at node i and the other phases. This represents the rotation factor in the symmetric component transformation.

[0013] Furthermore, the backward scan subroutine is specifically as follows:

[0014] Obtain the positive, negative, and zero-order network state vectors of the user, perform iterative solutions, obtain the updated value of the positive order vector correction and the correction result of the negative and zero order state vectors, and obtain the new positive, negative, and zero-order network state vectors of the user.

[0015] Obtain the voltage of phase q at node j in the h-th iteration. Based on the voltage of phase q at node j in the h-th iteration and the internal current source of the electronic interface distributed energy generator, the branch in the h+1-th iteration is calculated. l p-phase current ;

[0016] ;

[0017] ;

[0018] in, This represents the current source corresponding to the large motor connected at phase p of node j. This indicates the current source corresponding to the load of the large motor connected to phase p of node j. To compensate for the current source, For parallel admittance, The successor set formed by successor circuits. For subsequent circuits, This represents the p-phase current in the subsequent circuit d. This represents the circuit breaker compensation current at the p-phase of node j.

[0019] Furthermore, the forward scan subroutine is as follows:

[0020] Obtain the branch in the (h+1)th iteration l q-phase current Based on the branch of the (h+1)th iteration l Calculate the current in phase p and the voltage in phase p at node j in the (h+1)th iteration. .

[0021] Furthermore, the specific steps of the single-threaded power flow calculation method for integrated power transmission and distribution networks by calling the backward scan subroutine and the forward scan subroutine are as follows:

[0022] Initialize the index y to 1 and the iteration count h to 0;

[0023] A backward scan subroutine is applied to the y-th user-side network to obtain the branches of the user-side network in the (h+1)-th iteration. l The current in phase p will affect the branch of the user-side network in the (h+1)th iteration. l The multiphase complex power of the user-side network is obtained by multiplying the current of phase p and the voltage of phase q at node j of the user-side network in the h-th iteration, and then injecting the multiphase complex power of the user-side network into the corresponding transmission bus.

[0024] Then, a backward scan subroutine is applied to the y-th distribution network to obtain the branches of the distribution network in the (h+1)-th iteration. l The current in phase p of the distribution network in the (h+1)th iteration will be used for the branch. l The multiphase complex power of the distribution network is obtained by multiplying the current of phase p and the voltage of phase q at node j of the distribution network in the h-th iteration, and then injecting the multiphase complex power of the distribution network into the corresponding transmission bus.

[0025] Obtain the positive, negative, and zero-order network state vectors of the user, perform iterative solutions, obtain the updated value of the positive order vector correction and the correction result of the negative and zero order state vectors, and obtain the new positive, negative, and zero-order network state vectors of the user.

[0026] The approximate transmission bus voltage of the distribution network is taken as the root of the local distribution network;

[0027] A forward scanning subroutine is used for the y-th distribution network to obtain the voltage of phase p at node j of the distribution network in the (h+1)-th iteration. The root of the local user network is calculated based on the voltage of phase p at node j of the distribution network in the (h+1)-th iteration.

[0028] A forward scan subroutine is used on the y-th user-side network to obtain the voltage of phase p at node j of the user-side network in the (h+1)-th iteration;

[0029] Determine if the convergence condition is met. If it is, update y to y+1 and repeat the above steps until y reaches the upper limit of the number of networks. Otherwise, update h to h+1 and repeat the above steps.

[0030] Furthermore, the specific steps of the multi-threaded power flow calculation method for integrated power transmission and distribution networks by calling the backward scan subroutine and the forward scan subroutine are as follows:

[0031] Initialize the index y to 1 and the iteration count h to 0. Simultaneously, for y = 1, 2, 3...yn, where yn represents the upper limit of the network size, perform the following steps:

[0032] A backward scan subroutine is applied to the y-th user-side network to obtain the branches of the user-side network in the (h+1)-th iteration. l The current in phase p will affect the branch of the user-side network in the (h+1)th iteration. l The multiphase complex power of the user-side network is obtained by multiplying the current of phase p and the voltage of phase q at node j of the user-side network in the h-th iteration, and then injecting the multiphase complex power of the user-side network into the corresponding transmission bus.

[0033] Then, a backward scan subroutine is applied to the y-th distribution network to obtain the branches of the distribution network in the (h+1)-th iteration. l The current in phase p of the distribution network in the (h+1)th iteration will be used for the branch. l The multiphase complex power of the distribution network is obtained by multiplying the current of phase p and the voltage of phase q at node j of the distribution network in the h-th iteration, and then injecting the multiphase complex power of the distribution network into the corresponding transmission bus.

[0034] Obtain the positive, negative, and zero-order network state vectors of the user, perform iterative solutions, obtain the updated value of the positive order vector correction and the correction result of the negative and zero order state vectors, and obtain the new positive, negative, and zero-order network state vectors of the user.

[0035] The approximate transmission bus voltage of the distribution network is taken as the root of the local distribution network;

[0036] A forward scanning subroutine is used for the y-th distribution network to obtain the voltage of phase p at node j of the distribution network in the (h+1)-th iteration. The root of the local user network is calculated based on the voltage of phase p at node j of the distribution network in the (h+1)-th iteration.

[0037] A forward scan subroutine is used on the y-th user-side network to obtain the voltage of phase p at node j of the user-side network in the (h+1)-th iteration;

[0038] Determine if the convergence condition is met. If it is, end the power flow calculation for sequence number y. Otherwise, update h to h+1 and repeat the above steps.

[0039] Furthermore, the positive-order, negative-order, and zero-order network state vectors are as follows:

[0040] ;

[0041] in, This indicates that the node is a node in the power transmission network. This represents the state vector of the orthogonal network. This represents the negative-order network state vector. This represents the zero-order network state vector. Represents the set of busbars. Represents a node; 3PQ Direct busbar between user-side network and transmission network; 3P D Q D A special bus in a power distribution network is a node where the entire power distribution network is connected. Both single-phase active power and reactive power are functions of the power distribution network's state vector.

[0042] and V: The bus of the equivalent resistance control strategy, the former has fixed combined active power and combined reactive power, and the latter has fixed combined active power and control voltage;

[0043] I: The busbar of the control strategy for the electronic interface distributed energy generator that can inject three-phase current, with fixed integrated active power and integrated reactive power and controlled current;

[0044] V sym The busbar of the distributed energy generator control strategy with electronic interface can maintain the three-phase voltage balance of the busbar, and the comprehensive active power and comprehensive reactive power are fixed and the three-phase voltage is maintained.

[0045] Furthermore, the local power distribution network root is:

[0046] ;

[0047] in This represents the local distribution network root of the m-th single-phase distribution network circuit. Let be the voltage sequence component of node i in the transmission network. The positive sequence component of the voltage sequence component is the sum of the updated value of the positive sequence vector correction and the current positive sequence component of node i in the transmission network. The negative sequence component and the zero sequence component of the voltage sequence component are the correction results of the negative sequence and zero sequence state quantities, respectively. The transmission network is connected to the m-th distribution network based on node i.

[0048] Furthermore, the updated value of the orthogonal vector correction is:

[0049] ;

[0050] in, This is the updated value of the orthogonal vector correction. This represents the active / reactive power residual vector of the transmission network. is the Jacobian matrix of the orthogonal part.

[0051] Furthermore, the convergence condition is specifically: when the update value of the positive order vector correction is satisfied... ,in As the vector correction threshold, the voltages of the distribution network and user-side network nodes satisfy... and When convergent, it converges; otherwise, it does not converge. For a single-phase distribution network and a user-side network node i, the voltage amplitude of phase p is given. For a single-phase distribution network and a user-side network node i, the phase angle of the p-phase voltage is given. For single-phase distribution networks and user-side network node voltage amplitude thresholds, This refers to the voltage phase angle threshold for single-phase distribution networks and user-side network nodes.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] This invention constructs a power flow calculation model that combines three-phase transmission and multi-phase distribution. The transmission network adopts sequence domain modeling (positive sequence, negative sequence, zero sequence) to simplify the calculation of symmetrical operating conditions and take into account the unbalance characteristics. The distribution network and user side adopt phase domain modeling to accurately adapt to single-phase load and distributed power access scenarios, avoiding redundant calculations caused by one-size-fits-all modeling. At the same time, it customizes differentiated control strategies for traditional energy and electronic interface distributed energy, deeply embedding various control strategies into the calculation process of branch current and node power, reducing invalid iterations, thereby shortening the single-thread calculation time.

[0054] This invention also proposes a multi-threaded parallel architecture for the user-side and distribution network, allowing backward and forward scans of multiple user-side and distribution networks to be executed synchronously. Simultaneously, by centrally collecting power injection results, uniformly updating the transmission network sequence domain state vector, and coordinating synchronization point calibration, it balances the efficiency of parallel computing with the accuracy of overall network power balance, avoiding the coordination lag problem of traditional network decomposition methods. This invention, combined with precise convergence threshold control and sequence domain-phase domain connection design, further ensures computational accuracy, ultimately achieving high efficiency in single-threaded operation and improved quality and efficiency in multi-threaded operation, highlighting the characteristics and advantages of this solution compared to existing technologies. Attached Figure Description

[0055] Figure 1 This is a schematic flowchart of a single-threaded and multi-threaded power flow calculation method for an integrated power transmission and distribution network according to an embodiment of the present invention;

[0056] Figure 2 This is a comparison diagram of traditional energy and electronic interface distributed energy power generation sources according to an embodiment of the present invention;

[0057] Figure 3 This is a flowchart of the multi-threaded power flow calculation iteration according to an embodiment of the present invention;

[0058] Figure 4 This is a model diagram of a small-scale power transmission network according to one embodiment of this solution. Detailed Implementation

[0059] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0060] This invention proposes a single-threaded and multi-threaded power flow calculation method for integrated power transmission and distribution networks. A mathematical model of controllable energy is established, divided into a traditional energy model for the transmission network and an electronic interface distributed energy model. The integrated transmission and distribution user network is calculated based on Newton's method for the transmission network and the forward-backward substitution method for the distribution network and electronic interface distributed energy network. The transmission network is modeled using the sequence domain, while the distribution network and user-side network are modeled using the phase domain. The execution steps of forward and backward scanning are analyzed, and a single-threaded calculation model is established and derived to multi-threaded operation. The load power and the relationships between the various parts are analyzed from four aspects: the overall network, the transmission side, the distribution side, and the user side. A small transmission network is used as a test system, and the system is calculated based on the single-threaded and multi-threaded power flow methods for integrated power transmission and distribution networks, verifying that the proposed method has the characteristics of high speed and high accuracy.

[0061] Take the following steps:

[0062] S1 establishes a mathematical model for controllable energy, which is divided into a traditional energy model in the power transmission network and a distributed energy model with electronic interfaces.

[0063] S2 calculates the integrated transmission and distribution user network based on Newton's method for transmission networks and forward and backward substitution methods for distribution networks and electronic interface distributed energy networks. The transmission network is modeled using the sequence domain, while the distribution network and user-side network are modeled using the phase domain.

[0064] S3 analyzes the execution steps of forward and backward scans, establishes a single-threaded computation model, and derives it to multi-threaded operation. It analyzes load power and the relationships between these components from four aspects: the overall network, transmission side, distribution side, and user side.

[0065] S4 uses a small transmission network as the test system and calculates the system based on single-threaded and multi-threaded power flow methods for integrated transmission and distribution networks, verifying that the method has the characteristics of high speed and high accuracy.

[0066] Mathematical models of controllable energy are divided into traditional energy models in power transmission networks and distributed energy models using electronic interfaces.

[0067] In traditional energy models, three-phase composite power in the domain is used. ,Voltage Current Energy resources are quantitatively characterized, and then the three-phase voltage and current are converted into sequence domain quantities:

[0068]

[0069] In the formula, Let be the transformation matrix. For phase, These represent the phases a, b, and c, respectively.

[0070] The three-phase composite power in the sequence domain is calculated using the following formula:

[0071]

[0072] In the formula, , These represent the active power and reactive power in the sequence domain, respectively.

[0073] The generator units in a power transmission network are essentially power balancing elements, and the three-phase power is calculated using the following formula:

[0074]

[0075] In the formula, , These represent the three-phase active power and reactive power, respectively.

[0076] The control strategies for traditional energy power generation equipment are as follows:

[0077] (1) Synchronous motor

[0078] Three-phase active power There are three operating modes when under control: (a) Generator mode >0; (b) Compensator mode =0; (c) Motor mode <0. In any of the above operating modes, the following can be selected: (a) Controlling three-phase reactive power. >0 or =0 or <0; (b) Control voltage positive sequence amplitude .

[0079] (2) Induction motor

[0080] Three-phase active power can be used for both power generation and load supply; while three-phase reactive power is only used to meet the operating requirements of equipment and cannot participate in the actual power generation process.

[0081] In the formula, The ambient temperature; The temperature measured during the testing of the photovoltaic power generation module.

[0082] These are the sequence components of the internal source current. Observing from the generator end towards the generator, the admittances of the positive-sequence, negative-sequence, and zero-sequence Norton equivalent circuits can be obtained. -, 0.

[0083] Additional control strategies for distributed energy generation equipment adjust the internal source current. To achieve this, calculate using the following formula:

[0084]

[0085] Based on this, the power generation equipment sequence circuit can be further developed for different scenarios. After power flow calculation, the internal power supply current is obtained through calculation.

[0086] The control strategy of traditional distributed energy generators is basically the same as that of traditional energy engines described above. The comparison of their positive, negative, and zero-sequence power generation circuits is as follows: Figure 2 As shown. The control strategy for the electronic interface distributed energy generator is as follows:

[0087]

[0088] Internal current source of electronic interface distributed energy generator Since they are symmetrically distributed, the internal current sources of phases b and c are calculated using the following formula:

[0089]

[0090] The decoupled distributed generation model for power flow in the distribution network is calculated using the following formula:

[0091]

[0092] In the formula, the current source For phase p and the other phases Capacitive coupling between them.

[0093] The internal current source of the electronic interface distributed energy generator is calculated using the following formula:

[0094]

[0095] When this method is applied to power flow calculation in distribution networks, if an additional control strategy is adopted and a balancing current is injected at the interface of the electronic interface distributed energy generator, the admittance will be 0.

[0096] The integrated transmission and distribution user network is calculated based on Newton's method for transmission networks and forward-backward substitution methods for distribution networks and electronic interface distributed energy networks. The transmission network is modeled using the sequence domain, while the distribution network and user-side network are modeled using the phase domain.

[0097] The primary objective of power flow calculation is to determine all state variables in the integrated transmission and distribution network. In the transmission network, these variables are represented by three-phase node voltages, while in the distribution network at the load level, they are represented by multi-phase node voltages. Assume there is a summation point, and the number of data nodes is... The number of relay nodes in each data node is The number of three-phase nodes in the transmission network is The number of three-phase nodes in a renewable power transmission network is Its state variables have the following three states:

[0098] (1) Transmission status

[0099] Due to the highly unbalanced state of distributed distribution networks, the asymmetry of transient networks needs to be considered. This exists in the phase domain. Each single-phase complex voltage also has the same number in the sequence domain ( The complex voltage of ). Therefore, when using a sequence coordinate system, it is necessary to handle The positive-order components of a real value. The negative-sequence component and zero-sequence node voltage component of each complex value are calculated using the following formula to obtain the state vector of the transmission network node:

[0100]

[0101] (2) Distribution status

[0102] Since the distribution network is a multiphase system, the phase domain is selected for calculation. In the phase domain, the number of single-phase node voltages in each distribution network is... ,in For the distribution network node phase set, Given the cardinality of this set, its distribution state vector (the state vector of the distribution network node) is calculated using the following formula:

[0103]

[0104] (3) User status

[0105] Distribution network nodes have multiphase characteristics, and the number of single-phase node voltages in each user network is... ,in For nodes in the phase set, The size of the set.

[0106] Its user network state vector is calculated using the following formula:

[0107]

[0108] The control proposed above is achieved by incorporating an advanced bus classification method into power flow calculation. The symbolic variables required to construct the vector are shown below:

[0109] 3 Three-phase differential busbar.

[0110] 3PQ The user is directly connected to the power transmission network bus.

[0111] 3P D Q D The entire distribution network is connected at this node, and both single-phase active power and reactive power are functions of the distribution network state vector.

[0112] and V: Equivalent resistance control strategy.

[0113] I and VI: Control strategy for electronically interfaced distributed energy generators capable of injecting three-phase current.

[0114] V sym and V sym : Electronic interface distributed energy generator control strategy that can maintain the three-phase voltage balance of the bus.

[0115] The parameters mentioned above are solved using implicit equations and then substituted into explicit equations to solve for other unknowns. (Settings...) Given a quantity and its corresponding node number The indices are the same. The user network state vector can be calculated using the following formula:

[0116]

[0117] In the formula The dimension is , and The dimension is , Total Existence An unknown real-order state quantity and 2*( ( ) unknown complex negative and zero-order state variables. , and Given the user's positive, negative, and zero-order network state vectors, the equations that need to be solved are as follows:

[0118]

[0119]

[0120]

[0121]

[0122]

[0123] Update amount on the left side of the above formula:

[0124]

[0125]

[0126]

[0127]

[0128] The positive-sequence, negative-sequence, and zero-sequence components of the model are coupled together through the above equation. The positive-sequence component is solved using a single iteration of Newton's method, while the negative-sequence and zero-sequence components are solved using a single iteration of the implicit Zbus Gaussian method, calculated using the following formula:

[0129]

[0130] In the formula, The active / reactive power residual vector. Let be the Jacobian matrix of the orthogonal part. and This refers to the vector on the left side of the previous text. (Matrix) and The admittances of traditional negative-sequence and zero-sequence buses are derived from this.

[0131] By solving the three linearized relations in the above equation, the positive order vector correction can be obtained. Updated values ​​and negative-order zero-order state variables and The corrected results.

[0132] Decoupling circuits are used for power flow calculation in distribution networks. The circuit connects a predecessor circuit at the first node, and derives multiple successor circuits from the second node jp, whose indices form a successor set. The decoupling circuit is derived through the following steps:

[0133] 1. Employs a unique compensation current source and parallel admittance Replace all compensation current sources and parallel admittances in circuit l and subsequent circuit v.

[0134] 2. Deriving the impedance and compensation voltage .

[0135] 3. The load and the large motor connected at the second node JP are respectively connected using current sources. and This indicates that the load source is obtained through power flow calculations and formula calculations. and .

[0136] Each single-phase distribution network is divided into three phases (a, b, and c) using the forward-backward substitution method. In the h-th iteration, the updated values ​​of branch currents and node voltages are obtained. The backward scan subroutine calculates these values ​​using the following formula:

[0137]

[0138] Calculated by backward scan The latest value for the total power consumption of wireless node x is equal to the single-phase complex power of the entire wireless node x connected to node j of the distribution network, calculated using the following formula:

[0139]

[0140] In the formula, This is a set of wireless node branch indexes.

[0141] The backward scan subroutine is also used for the user-side network, and the calculation process is the same as described above.

[0142] Calculated by forward scan The latest value is calculated by the forward scan subroutine using the following formula:

[0143]

[0144] The forward scan subroutine is also used for the user-side network, and the calculation process is the same as described above.

[0145] The compensation current at the circuit breaker point is calculated using the following formula:

[0146]

[0147] In the formula, and For all three-phase circuit breaking currents aggregation, This is the Thevenin circuit break matrix. This is the voltage deviation vector at the short-circuit point.

[0148] The internal source current of an electronically interfaced distributed energy generator is calculated using the following formula:

[0149] The root node of the local distribution network for the m-th single-phase distribution network circuit is calculated using the following formula:

[0150]

[0151] In the formula, Let be the voltage sequence component of node i in the transmission network, which is connected to node m in the distribution network.

[0152] The calculation process for the root of the local user network is the same as that for the root node of the local distribution network. The calculation formula for the root of the local user network includes... Let be the voltage sequence component of node i in the distribution network, which is connected to user network m.

[0153] Power shortage rate The percentage of power shortage in the total annual electricity load:

[0154]

[0155] The execution steps of forward and backward scans are calculated, a single-threaded calculation model is established, and its application to multi-threaded operation is derived. Load power and the relationships between these components are analyzed from four perspectives: the overall network, transmission side, distribution side, and user side.

[0156] The integrated transmission and distribution user network is calculated based on Newton's method for transmission networks and forward-backward substitution for distribution and renewable energy networks. The transmission network is modeled using the sequence domain, while the distribution and user-side networks are modeled using the phase domain. This model ensures that the entire integrated network is calculated in a single "inner layer" iteration, and can be applied in both single-threaded and multi-threaded environments.

[0157] This calculation program employs an improved flat-start method, ensuring that the voltage amplitude of all phases is equal to the voltage amplitude of the corresponding phase on the relaxation bus. The angles of phases b and c are rotated according to the phase displacement angle. Except when the node is located on the secondary side of the transformer and needs to be rotated according to the transformer phase displacement angle, the node phase angle is the same as the angle of the relaxation bus in all other cases.

[0158] When satisfying condition 1, the positive sequence state vector update correction amount 2. The voltage of single-phase power distribution and user-side network nodes meets the requirements. At that time, the power flow calculation ends.

[0159] The execution steps of a backward scan can be derived from the single-threaded model:

[0160] 1. M1a: Performs a reverse scan independently in each network;

[0161] M1b: Total network power injected into the corresponding distribution network;

[0162] 2. M2a: Performs reverse scan independently in each distribution network;

[0163] M2b: Total power from the distribution network is injected into the main grid.

[0164] The execution steps for forward scanning and backward scanning are the same. In multi-threaded mode, steps ① and ② can be executed simultaneously.

[0165] In n R Each thread simultaneously performs a reverse scan of all user-side networks, and the results of all reverse scan threads are collected at a synchronization point. The result is the calculated load power, which is injected into the busbar connected to the user side in the distribution network. Then, in n... D Each thread simultaneously performs reverse scan calculations on all distribution networks, while the synchronization point collects the results from all threads. During this phase, the calculation results are the power values ​​of each branch of all distribution networks, as well as the power values ​​injected into the root nodes located at the connection points between the transmission and distribution networks.

[0166] In power flow calculations for transmission networks, the voltage of the transmission network nodes connected to the distributed network is calculated to determine the updated root voltage value of the distributed network.

[0167] In n D Each thread performs a forward scan of the entire user-side network, and the results of all forward scan threads are collected at a synchronization point. Then, in n... R Each thread performs a forward scan of all distribution networks simultaneously, and the convergence criteria are as described above.

[0168] The multi-threaded power flow calculation method is as follows:

[0169] 1. Initialize the unknown state variables by inputting the parameters of the transmission components, the advanced bus distribution, the parameters of the distribution network components, the parameters of the user-side network, and the initial values ​​of the unknown state variables. (Corresponding to...) Figure 3 (The input data section).

[0170] 2. For each user-side network, a backward scan subroutine is used to calculate the multiphase complex power and inject it into the corresponding transmission bus. This step corresponds to... Figure 3 The M1a and M1b parts.

[0171] 3. For each distribution network, a backward scan subroutine is used to calculate the multiphase complex power and inject it into the corresponding transmission bus. This step corresponds to... Figure 3 The M2a and M2b parts.

[0172] 4. Perform a power flow calculation on the transmission network, i.e., use the new approximate transmission bus voltage connected to the distribution network as the root of the local distribution network (i.e., the relaxation bus), and then apply a forward scan sub-process to each distribution network. This step corresponds to... Figure 3 The M3, M4a and M4b sections.

[0173] 5. Use the new approximate transmission bus voltage connected to the user side as the root of the local user network (i.e., the relaxed bus), and perform a forward scan sub-procedure for each user network. This step corresponds to... Figure 3 The M5a and M5b sections.

[0174] 6. Repeat steps 2-5 above until the convergence condition is met.

[0175] Using a small power transmission network as the test system, the system was calculated based on single-threaded and multi-threaded power flow calculation methods for integrated power transmission and distribution networks, verifying that the method has the characteristics of high speed and high accuracy.

[0176] Compared to existing technologies, the advantages are as follows: It provides a single-threaded and multi-threaded power flow method for integrated transmission and distribution networks, constructing a power flow calculation model combining three-phase transmission and multi-phase distribution. It also compares different control strategies implemented in traditional energy sources and electronically interfaced distributed energy sources, proposing a multi-threaded solution to establish the power flow model. Compared to traditional attention-based network decomposition methods, this method consumes less time in single-threaded calculations and improves the efficiency and accuracy of power flow calculations in multi-threaded calculations. The effectiveness of the model is verified through implementation examples, clarifying the characteristics and advantages of this scheme.

[0177] Flowchart as follows Figure 1 As shown,

[0178] Figure 3 The iterative process of the multi-threaded power flow calculation method is demonstrated. This mode performs forward and backward scans on multiple user sides and distribution network sides simultaneously, which improves the calculation speed, allows for rapid iterative updates of results, and yields more accurate final values.

[0179] Step S4: Using a small power transmission network as the test system, the system is calculated based on single-threaded and multi-threaded power flow methods of integrated power transmission and distribution networks to verify that the method has the characteristics of high speed and high accuracy.

[0180] The specific implementation process is as follows:

[0181] First, set the convergence criterion for all state variables to 10. -7 The improved flat-start method mentioned in S3 was used for testing. The test system is as follows: Figure 4 The diagram shows a small power transmission network where all transmission lines are of equal length. The initial settings of the system are shown in Table 1.

[0182] Table 1 Initial State Settings of the Test System

[0183]

[0184] In this system, traditional energy sources are connected to buses 1, 2, and 5, while distributed energy sources via electronic interfaces are connected to buses 6, 9, 10, and 13. Tests were conducted on various large-scale systems containing 23,235 to 590,515 nodes. The computational speedup was 1.12 in the minimum network configuration (fewest nodes) and 2.39 in the maximum network configuration (most nodes), showing a significant improvement in speedup as the number of nodes increases. With increasing numbers of digital nodes, multithreading significantly outperforms single-threaded execution, achieving a computation speed more than twice that of single-threaded execution.

[0185] Example 2:

[0186] This embodiment provides a system including a memory and a processor. The memory stores a computer program, and the processor calls the computer program to execute the steps of the method as described in Embodiment 1.

[0187] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0188] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of the present invention can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0189] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A system that specifies functions in one or more boxes.

[0190] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including an instruction set implemented in a process. Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0191] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0192] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

[0193] The results show that the single-threaded and multi-threaded power flow calculation methods for integrated power transmission and distribution networks proposed in this invention can provide accurate results for power flow calculation in large-scale multi-threaded systems, and exhibit good performance in terms of iteration speed and calculation accuracy.

Claims

1. A single-threaded and multi-threaded power flow method for integrated power transmission and distribution networks, characterized in that, The method includes the following steps: A mathematical model of controllable energy is established to obtain the internal current source of the electronic interface distributed energy generator; A backward scanning subroutine is constructed based on an internal current source, and a forward scanning subroutine is also constructed. Call the backward scan subroutine and the forward scan subroutine to perform single-threaded or multi-threaded power flow calculations for the integrated power transmission and distribution network until the convergence condition is met; The forward scan subroutine is as follows: Obtain the branch in the (h+1)th iteration l q-phase current Based on the branch of the (h+1)th iteration l Calculate the current in phase p and the voltage in phase p at node j in the (h+1)th iteration. ; The specific steps for performing single-threaded power flow calculations for integrated power transmission and distribution networks by calling the backward scan subroutine and the forward scan subroutine are as follows: Initialize the index y to 1 and the iteration count h to 0; A backward scan subroutine is applied to the y-th user-side network to obtain the branches of the user-side network in the (h+1)-th iteration. l The current in phase p will affect the branch of the user-side network in the (h+1)th iteration. l The multiphase complex power of the user-side network is obtained by multiplying the current of phase p and the voltage of phase q at node j of the user-side network in the h-th iteration, and then injecting the multiphase complex power of the user-side network into the corresponding transmission bus. Then, a backward scan subroutine is applied to the y-th distribution network to obtain the branches of the distribution network in the (h+1)-th iteration. l The current in phase p of the distribution network in the (h+1)th iteration will be used for the branch. l The multiphase complex power of the distribution network is obtained by multiplying the current of phase p and the voltage of phase q at node j of the distribution network in the h-th iteration, and then injecting the multiphase complex power of the distribution network into the corresponding transmission bus. Obtain the positive, negative, and zero-order network state vectors of the user, perform iterative solutions, obtain the updated value of the positive order vector correction and the correction result of the negative and zero order state vectors, and obtain the new positive, negative, and zero-order network state vectors of the user. The approximate transmission bus voltage of the distribution network is taken as the root of the local distribution network; A forward scanning subroutine is used for the y-th distribution network to obtain the voltage of phase p at node j of the distribution network in the (h+1)-th iteration. The root of the local user network is calculated based on the voltage of phase p at node j of the distribution network in the (h+1)-th iteration. A forward scan subroutine is used on the y-th user-side network to obtain the voltage of phase p at node j of the user-side network in the (h+1)-th iteration; Determine if the convergence condition is met. If yes, update y to y+1 and repeat the above steps until y reaches the network capacity limit. Otherwise, update h to h+1 and repeat the above steps. The specific steps for multi-threaded power flow calculation of the integrated transmission and distribution network by calling the backward scan subroutine and the forward scan subroutine are as follows: Initialize the index y to 1 and the iteration count h to 0. Simultaneously, for y = 1, 2, 3...yn, where yn represents the upper limit of the network size, perform the following steps: A backward scan subroutine is applied to the y-th user-side network to obtain the branches of the user-side network in the (h+1)-th iteration. l The current in phase p will affect the branch of the user-side network in the (h+1)th iteration. l The multiphase complex power of the user-side network is obtained by multiplying the current of phase p and the voltage of phase q at node j of the user-side network in the h-th iteration, and then injecting the multiphase complex power of the user-side network into the corresponding transmission bus. Then, a backward scan subroutine is applied to the y-th distribution network to obtain the branches of the distribution network in the (h+1)-th iteration. l The current in phase p of the distribution network in the (h+1)th iteration will be used for the branch. l The multiphase complex power of the distribution network is obtained by multiplying the current of phase p and the voltage of phase q at node j of the distribution network in the h-th iteration, and then injecting the multiphase complex power of the distribution network into the corresponding transmission bus. Obtain the positive, negative, and zero-order network state vectors of the user, perform iterative solutions, obtain the updated value of the positive order vector correction and the correction result of the negative and zero order state vectors, and obtain the new positive, negative, and zero-order network state vectors of the user. The approximate transmission bus voltage of the distribution network is taken as the root of the local distribution network; A forward scanning subroutine is used for the y-th distribution network to obtain the voltage of phase p at node j of the distribution network in the (h+1)-th iteration. The root of the local user network is calculated based on the voltage of phase p at node j of the distribution network in the (h+1)-th iteration. A forward scan subroutine is used on the y-th user-side network to obtain the voltage of phase p at node j of the user-side network in the (h+1)-th iteration; Determine if the convergence condition is met. If it is, end the power flow calculation for sequence number y. Otherwise, update h to h+1 and repeat the above steps.

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