Power distribution network voltage fluctuation control method and device considering communication time delay

Abstract

The invention discloses a power distribution network voltage fluctuation control method and device considering communication time lag. The method is applied to a distributed photovoltaic power distribution network, the power distribution network at least comprises a cooperative controller and a plurality of weak branches, each weak branch is connected with an impact load and an energy storage converter, and each energy storage converter corresponds to a local energy storage controller; the method comprises the following steps: uniformly modeling communication time lag between the cooperative controller and each local energy storage controller, and distributing the communication time lag to a power distribution link to obtain a power distribution small signal model containing the time lag; constructing a state space model of the energy storage converter; unifying the power distribution small signal model and the state space model of the energy storage converter to a common reference coordinate system to obtain a whole system state equation; and performing voltage control on the power distribution network based on the full-system state equation. The influence of communication delay on the stability of the power distribution network can be eliminated.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power generation technology, and in particular to a method and apparatus for controlling voltage fluctuations in distribution networks that takes into account communication time delays. Background Technology

[0002] With the increasingly tight supply of traditional fossil fuels, solar photovoltaic (PV) power generation is experiencing rapid development. While distributed PV is driving energy transformation, its high grid penetration rate also exacerbates system operational risks. In particular, millisecond-level power surges in pulse loads such as dyeing and printing machines and rolling mills can cause rapid voltage fluctuations, potentially triggering protection devices and causing localized power outages. Traditional on-load tap changers, limited by mechanical inertia, cannot handle such transient disturbances with their secondary response speed. Distributed energy storage converters, due to their flexible and rapid power regulation capabilities, are considered an effective means of mitigating voltage fluctuations. However, existing research largely focuses on long-term voltage optimization problems, neglecting the impact of communication delays on system transient disturbances. Therefore, it cannot overcome the impact of pulse loads on distribution network stability.

[0003] Therefore, there is an urgent need for a real-time, wide-area, long-range maritime target detection method to solve the above problems. Summary of the Invention

[0004] This invention provides a method and apparatus for controlling voltage fluctuations in a distribution network that considers communication delays, thereby eliminating the impact of communication delays on the stability of the distribution network. The technical solution is as follows: On the one hand, a distribution network voltage fluctuation control method considering communication time delay is provided, applied to a distributed photovoltaic distribution network. The distribution network includes at least a coordinated controller and multiple weak branches, each of which is connected to an impulsive load and an energy storage converter, and each energy storage converter corresponds to a local energy storage controller. The method includes: The communication delay between the collaborative controller and each of the local energy storage controllers is modeled in a unified manner and allocated to the power allocation stage to obtain a power allocation small-signal model with time delay. Construct a state-space model of the energy storage converter; By unifying the power distribution small-signal model and the state-space model of the energy storage converter into a common reference coordinate system, the state equations of the entire system are obtained. Voltage control of the distribution network is performed based on the state equations of the entire system.

[0005] On the other hand, a distribution network voltage fluctuation control device that takes into account communication time delay is provided for implementing the above method, the device comprising: The first modeling unit is used to uniformly model the communication time delay between the cooperative controller and each of the local energy storage controllers, and allocate it to the power allocation stage to obtain a power allocation small-signal model with time delay. The second modeling unit is used to construct the state-space model of the energy storage converter. A unified unit is used to unify the power distribution small-signal model and the state-space model of the energy storage converter into a common reference coordinate system to obtain the state equations of the entire system. The control unit is used to perform voltage control on the distribution network based on the overall system state equation.

[0006] On the other hand, a computer device is provided, the computer device including a memory and a processor, the memory for storing a computer program, and the processor for executing the computer program stored in the memory to implement the steps of the above-described distribution network voltage fluctuation control method considering communication delay.

[0007] On the other hand, a computer-readable storage medium is provided, wherein a computer program is stored therein, and when the computer program is executed by a processor, the steps of the above-described distribution network voltage fluctuation control method considering communication delay are implemented.

[0008] On the other hand, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps of the above-described distribution network voltage fluctuation control method considering communication delay.

[0009] This invention provides a distribution network voltage fluctuation control method considering communication delay. By uniformly modeling the communication delay between the cooperative controller and the local energy storage controller and allocating it to the power allocation stage, a two-layer control architecture of "cooperative power allocation - local PCS execution" can be obtained, achieving rapid voltage balance of weak nodes under pulse load disturbances. Simultaneously, a system-wide state equation considering the delay is established. This state equation can be used to analyze the interaction mechanism between phase-locked loop parameters and communication delay, and to derive the critical delay threshold and safety domain of the controller parameters to ensure system stability, which is beneficial for distribution network stability control. Therefore, this application can eliminate the impact of communication delay on distribution network stability. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a flowchart of a distribution network voltage fluctuation control method considering communication time delay provided by an embodiment of the present invention; Figure 2 This is a distributed collaborative control distribution network structure diagram provided by an embodiment of the present invention; Figure 3 This is a schematic diagram of the main circuit structure of an energy storage converter provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of energy storage converter control provided in an embodiment of the present invention; Figure 5 This is a structural diagram of an energy storage converter controller provided in an embodiment of the present invention; Figure 6 This is a diagram of the phase-locked loop control structure of an energy storage converter according to an embodiment of the present invention; Figure 7 This is a power control structure diagram of an energy storage local controller provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the voltage distribution of the power distribution system when a 10KW load is added to both ordinary branch 1 and ordinary branch 2, according to an embodiment of the present invention. Figure 9 This is a schematic diagram of the voltage distribution of the power distribution system when a 10KW load is added to both weak branch 1 and weak branch 2, according to an embodiment of the present invention. Figure 10 This is a schematic diagram illustrating the influence of different communication delays on the eigenvalues ​​in weak branch 1 according to an embodiment of the present invention; Figure 11 This is a response curve of the power and voltage of the energy storage node in the weak branch 2 of the power distribution and substation system to different communication delays, provided by an embodiment of the present invention. Figure 12 This is a periodic input curve of the impact load provided in an embodiment of the present invention; Figure 13 This is an embodiment of the present invention, showing the influence of different communication delays on the voltage of each node in weak branch 1; Figure 14 This is a structural diagram of a power distribution network voltage fluctuation control device that takes into account communication time delay, provided in an embodiment of the present invention; Figure 15 This is a hardware architecture diagram of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0013] The specific implementation of the method in this application is described in detail below.

[0014] Please refer to Figure 1 This invention provides a distribution network voltage fluctuation control method considering communication time delay, applied to a distributed photovoltaic distribution network. The distribution network includes at least a coordinated controller and multiple weak branches, each weak branch is connected to an impulsive load and an energy storage converter, and each energy storage converter corresponds to a local energy storage controller; the method includes: Step 100: The communication time delay between the collaborative controller and each local energy storage controller is modeled in a unified manner and allocated to the power allocation stage to obtain a power allocation small-signal model with time delay. Step 102: Construct the state-space model of the energy storage converter; Step 104: Unify the small-signal model of power distribution and the state-space model of energy storage converter into a common reference coordinate system to obtain the state equations of the whole system. Step 106: Perform voltage control on the distribution network based on the state equations of the entire system.

[0015] In this embodiment, by uniformly modeling the communication delay between the cooperative controller and the local energy storage controller and allocating it to the power allocation stage, a two-layer control architecture of "cooperative power allocation - local PCS execution" can be obtained, achieving rapid voltage balance of weak nodes under pulse load disturbances. Simultaneously, a system-wide state equation considering the delay is established. This state equation can be used to analyze the interaction mechanism between phase-locked loop parameters and communication delay, and to derive the critical delay threshold and safety domain of the controller parameters to ensure system stability, which is beneficial for the stability control of the distribution network. Therefore, this application can eliminate the impact of communication delay on the stability of the distribution network.

[0016] To better understand the scheme of this application, the system structure of the distribution network will be described in detail below, such as... Figure 2The diagram shows a distributed collaborative control architecture. As can be seen, the distribution network includes a main branch, two ordinary branches, and two vulnerable branches. The number of branches is determined based on actual conditions and is not specifically limited here. In the vulnerable branches, impulsive loads can be pulse loads such as dyeing machines and rolling mills, whose millisecond-level power surges can cause rapid voltage fluctuations. Figure 2 In the distribution network shown, the coordinated controller collects voltage information of weak nodes in the distribution network in real time, such as nodes 684 / 611 of weak branch 1 and nodes 692 / 675 of weak branch 2, and generates energy storage power allocation commands based on voltage deviations. The local controller (i.e., the local controller) in the energy storage converter (PCS) receives power commands sent through the communication link and suppresses voltage fluctuations by rapidly adjusting the active power output.

[0017] The main circuit structure diagram of the energy storage converter (PCS) is as follows: Figure 3 As shown in the figure, u dc and C dc These represent the DC-side voltage and capacitance, respectively. L f , C f , L g These are the filter inductor, filter capacitor, and equivalent inductance between the power grid and the energy storage bus, respectively. U ga , U gb , U gc These represent the three-phase voltages on sides a, b, and c of the energy storage network, respectively, and are composed of batteries and DC / AC power conversion units. The DC / AC power conversion unit allows bidirectional energy flow for charging and discharging the energy storage battery, and determines the battery's charge level by controlling the conduction time of the control arms. The power conversion unit is the interface between the grid and the energy storage battery, converting the received DC power into AC power, which is then connected to the distribution substation via an LCL filter. During operation, voltage information collected from weak branches is transmitted to the coordinating controller for power distribution, and then transmitted via communication lines to the local controllers of the energy storage converters in each weak branch to address voltage fluctuations caused by sudden load changes.

[0018] like Figure 4 The diagram shown is a control schematic of an energy storage converter. In the diagram, It serves as the voltage reference for each node along the d-axis (q-axis); It is the voltage of node 684 in weak branch 1 on the d-axis (q-axis); It is the voltage of node 611 in weak branch 1 on the d-axis (q-axis); It is the voltage at node 692 in weak branch 2 on the d-axis (q-axis); It is the voltage at node 675 in weak branch 2 on the d-axis (q-axis); It is the voltage at node 684 in weak branch 1 on the d-axis (q-axis) after communication delay; It is the voltage of node 611 in weak branch 1 on the d-axis (q-axis) after communication delay; It is the voltage at node 692 in weak branch 2 on the d-axis (q-axis) after communication delay; It is the voltage at node 675 in weak branch 2 on the d-axis (q-axis) after communication delay; It is the active power (reactive power) allocated by the coordinated controller to the energy storage converter in the weak branch 1; It is the active power (reactive power) allocated by the coordinated controller to the energy storage converter in the weak branch 2; It is the active power (reactive power) allocated by the collaborative controller to the energy storage converter in the weak branch 1 after communication delay; It is the active power (reactive power) allocated by the collaborative controller to the energy storage converter in the weak branch 2 after communication delay; K 1Ed(q)p , K 1Ed(q)i These are the parameters in the proportional-integral controller for node 611 in weak branch 1 when the cooperative controller distributes active power (reactive power); K 2Ed(q)p , K 2Ed(q)i These are the parameters in the proportional-integral controller for node 675 in weak branch 2 when the cooperative controller distributes active power (reactive power); K 11Ed(q)p , K 12Ed(q)p These are the parameters for the active power (reactive power) allocation by the collaborative controller in the weak branch 1; K 21Ed(q)p , K 22Ed(q)i These are the parameters in the proportional-integral controller (PIC) when the cooperative controller in weak branch 2 allocates active power (reactive power). The cooperative controller transmits the allocated active power to the local controllers of the energy storage converters in each weak branch via communication lines. In actual control systems, delays are not fixed in one place; delays can occur at any stage of the control system. To simplify the analysis, the control communication delays for different weak branches are uniformly set as follows: and It is located in the power distribution stage.

[0019] like Figure 5The diagram shown is a structural diagram of an energy storage converter controller. In the diagram, u mo , i mo These are the three-phase voltages and currents (a, b, and c) on the energy storage grid side of the weak branch m. u mod , u moq , i mod and i moq These represent the output voltage and current of the energy storage grid side in the weak branch m along the dq axis in the rotating coordinate system; u mi , i mi These are the three-phase voltage and current input to the energy storage inverter in the weak branch m; u mid , u miq These are the energy storage voltages in the weak branch m, and the input voltages along the dq axes in the rotating coordinate system. P mPCS 、Q mPCS These are the reference values ​​for the active and reactive power of energy storage in the weak branch m, respectively. P, Q These are the active power and reactive power output from energy storage, respectively. L f The filter inductor is located on the energy storage converter side of the weak branch m. u dc This refers to the voltage on the DC side of the energy storage converter; i md 、i mq These are the currents generated by the energy stored in the weak branch m along the dq axis in the rotating coordinate system. i mdref 、i mqref These are the reference currents along the dq axis in the rotating coordinate system that need to be generated for energy storage in the weak branch m. q The electrical angle at which energy is stored is the operating angle at this time.

[0020] An energy storage converter comprises physical components and digital control components. The physical components include the energy storage battery, converter, filter, feeder resistor, and power grid. The digital components include sampling, power calculation, control, and pulse width modulation (PWM) stages. The control of the DC / AC conversion unit in energy storage consists of a power calculation stage and a current inner-loop control stage. The power calculation stage calculates the power that the energy storage needs to absorb or generate, and then uses this power as a current reference to supply the current inner-loop control stage to obtain a modulation wave. The modulation wave is compared with the reference wave to generate a modulation signal, which is finally used to control the switching of all controlled devices.

[0021] Based on the structure and working principle of the energy storage converter and cooperative controller described above, the following is a description Figure 1 The execution method for each step is shown.

[0022] First, regarding step 100, it includes: Construct the state-space model of the cooperative controller, the expression of which is as follows: In the formula, x mEd , x mEq It is a set of state variables when the collaborative controller distributes power to the energy storage converter in the weak branch m; u m1d , u m2d It is the d-axis voltage of each node when the collaborative controller distributes active power to the energy storage converter in the weak branch m; u m1q , u m2q It is the q-axis voltage of each node when the collaborative controller distributes active power to the energy storage converter in the weak branch m; P mf , Q mf These are the active and reactive power allocated by the coordinated controller to the energy storage converter in the weak branch m, respectively. K m1Ed(q)p , K m2Ed(q)p These are the parameters for the active power (reactive power) allocation by the collaborative controller in the weak branch m; K mEd(q)p , K mEd(q)i These are the parameters in the proportional-integral controller for a node in the weak branch m when the cooperative controller distributes active power (reactive power).

[0023] The state-space model of the cooperative controller is linearized to obtain its linearized small-signal model, as shown in the following expression: in, In the formula, , , These represent the power change, active power change, and reactive power change allocated by the coordinated controller to the energy storage converter in the weak branch m, respectively. , and These represent the total change in state variables, and the changes in the d-axis and q-axis, respectively, when the collaborative controller distributes power to the energy storage converter in the weak branch m. , , These are intermediate parameters.

[0024] Using the second-order Pade approximation, the acquired voltage information is transmitted via a communication line to the time-delay link in the local energy storage controller for equivalent processing, resulting in the equivalent state-space equation of the time-delay element. The rational equivalent result of the time-delay link is shown in the following equation: Linearizing the state-space equation of the equivalent post-delay stage yields a small-signal model of power allocation with time delay, as shown in the following equation: In the formula, Let be the equivalent change in the state variable of the time-delay element in the weak branch m. The change in the state variable of the time-delay element in the weak branch m; This represents the equivalent change in power signal in the weak branch m after the communication delay; , These represent the changes in active power and reactive power in the weak branch m after the communication delay, respectively. Communication delay for the weak branch m; , , , These are intermediate parameters.

[0025] For step 102, the state-space model of the energy storage converter includes: a phase-locked loop model, a power control model, a current inner loop model, and a filter model.

[0026] Each model is described in detail below.

[0027] (1) Phase-locked loop model like Figure 6 The diagram shown is a phase-locked loop (PLL) control structure diagram of an energy storage converter. In the diagram, K mpw 、K miwThese are the parameters of the PI controller in the phase-locked loop control loop of the energy storage converter in the weak branch m; ω n It is the rated angular frequency in the power distribution network; u m It is the output voltage of the energy storage converter in the weak branch m; ω m It is the angular frequency of the energy storage converter in the weak branch m; q m It is the electrical angle of the energy storage converter in the weak branch m.

[0028] The phase-locked loop control circuit can be expressed as: Linearizing the above equation, we obtain the small-signal state-space model of the phase-locked loop as follows: In the formula, x mw and q m It is a set of state variables of the phase-locked loop in the energy storage converter in the weak branch m; and They are respectively x mw and q m The change in; u moqref It is the reference value of the q-axis output voltage of the energy storage converter in the weak branch m; u mod and u moq These are the output voltages of the energy storage converter in the weak branch m on the d-axis and q-axis, respectively; △ u mod and △ u moq They are respectively u mod and u moq The change in; , , These are intermediate parameters.

[0029] (2) Power control model like Figure 7 The diagram shown is a power control structure diagram of an energy storage local controller. In the diagram, K mpp 、Kmip These are the parameters of the PI controller in the active power control loop of the energy storage power in the weak branch m; K mpq 、K miq These are the parameters of the PI controller in the reactive power control loop of the energy storage power in the weak branch m; K mip 、K mpp These are the parameters of the PI controller in the active power control loop of the energy storage power in the weak branch m; K mpid 、K miid , K mpiq 、K miiq These are the d-axis and q-axis parameters of the PI controller in the current closed-loop control loop of the energy storage power control unit in the weak branch m, respectively. C f 、L f For filtering inductors and capacitors; u mid 、u miq These are the d-axis and q-axis components of the input voltage of the energy storage converter controller in the weak branch m, respectively. i mdref 、i mqref These are the d-axis and q-axis components of the current reference for the energy storage converter controller in the weak branch m, respectively.

[0030] The active and reactive power generated or absorbed by the energy storage inverter are shown in the following formula: P m , Q m These represent the active power and reactive power after the proportional-integral (PI) stage, respectively.

[0031] (3) Current inner loop model The state equations for the inner current loop model are shown below: In the formula, and These are the state variables and effective state variables in the weak branch m, respectively; The change in the inner loop output voltage of the energy storage converter in the weak branch m during stable operation; i mod and i moq The output current in the dq axis coordinates of the energy storage converter in the weak branch m during stable operation; , These represent the active power and reactive power output of the energy storage converter in the weak branch m during stable operation, respectively. , These represent the changes in output current in the dq-axis coordinates of the energy storage converter in the weak branch m during stable operation. , , , , , , , These are intermediate parameters.

[0032] (4) Filter Model The energy storage converter uses an L-filter to filter the harmonics generated by the inverter. The state equation of the filter model is shown below: in, In the formula, The change in current output after filtering of the weak branch m; It is the angular frequency at which the distribution radio station operates stably; This represents the change in angular frequency of the weak branch m. , , , These are intermediate parameters.

[0033] For step 104, the small-signal model of power distribution and the state-space model of the energy storage converter are unified into a common reference coordinate system, resulting in the state equations of the entire system, as shown below: in, In the formula, This represents the equivalent change in the state variables of the entire system within the weak branch m. The change in the state variables of the entire system in the weak branch m; , , , These are the coefficient matrices of the weak branch m; This represents the equivalent change in current in the weak branch m. Z represents the change in voltage in the weak branch m; m The equivalent impedance of the energy storage converter connected in the weak branch m; T , T mv , T mi , B mDQ These are intermediate parameters.

[0034] Finally, for step 106, voltage control of the distribution network is performed based on the overall system state equations, including: Solve the state equations of the entire system to obtain the system's eigenvalues; The voltage value of the distribution network is adjusted based on the trajectory of the characteristic value change with the communication time delay.

[0035] Through the above process, this application enables voltage regulation and stability analysis of the power distribution network.

[0036] To demonstrate the effectiveness of this application, the inventors have... Figure 2 The distribution network shown was simulated and analyzed to verify the impact of the model under different conditions, as well as the impact of communication delay between different weak branches on the stability of the distribution network regional control system. Table 1 shows the operating parameters of the energy storage converter in the low-voltage distribution area.

[0037] Table 1 Operating parameters of energy storage converter in low-voltage distribution area (1) Verify the response of the method in this application under different scenarios. When a 10kW load is added to both ordinary branch 1 and ordinary branch 2, the pressure distribution curves at each node are as follows: Figure 8 As shown; when a 10KW load is added to both weak branch 1 and weak branch 2, the pressure distribution curves of each node are as follows. Figure 9 As shown in the figure, curve 1 indicates that when the hierarchical control does not participate in voltage regulation, the distribution zone system has a large load and a significant voltage drop. The distribution zone system needs voltage regulation to stabilize the voltage amplitude within a certain range. Curve 2 shows that when energy storage participates in voltage regulation in ordinary branches with hierarchical control, the voltage amplitude can only support the voltage of its own branch. Curve 3 indicates that the energy storage converter uses hierarchical control on weak branches to support the voltage of the distribution zone.

[0038] (2) Verify the impact of different communication delay times between weak branches on the stability of the distribution network control system. like Figure 10 As shown, in weak branch 2, the communication delay is 5ms. The eigenvalues ​​of weak branch 1 change with the communication delay. The communication delay is calculated every 10ms within the interval [0.01, 0.13]. τ As communication latency increases, the system's eigenvalues ​​gradually approach the right half-plane. When the communication latency reaches 130ms, it enters the right half-plane, at which point the system loses stability.

[0039] Figure 11 This figure shows the response of power and voltage at the energy storage node in the weak branch 2 of the distribution substation system to different communication delays. In the figure, the communication delay of the weak branch 1 is uniformly set to 5ms. Curve A represents the system operating in underdamped mode when the communication delay τ of the weak branch 2 is 10ms. Power and voltage regulation can be completed within 100ms. Curve B shows that when the communication delay τ is 50ms, the oscillation frequency of voltage and power in the energy storage controller decreases, damping decreases, but stability can still be restored. Curve C indicates that when the communication delay τ is 100ms, the voltage and power oscillate severely in the energy storage controller, and power and voltage regulation cannot be completed within 100ms. Curve D indicates that when the communication delay τ is 130ms, the voltage and power of the energy storage controller have lost tracking and completely lost stability.

[0040] This application employs periodic impact loading, and the periodic input curve of the impact load is as follows: Figure 12 As shown, the active power of each node load is 10kW. At t = 1s, the impact load starts with a power of 30kW and a power factor of 0.98. Then, it is periodically activated and deactivated every 0.5s. As can be seen from the figure, this will cause voltage fluctuations in the distribution substation. Therefore, corresponding measures need to be taken to reduce this impact.

[0041] Figure 13The communication delay of weak branch 2 is shown to be 10ms, while the communication delays of the energy storage converter in weak branch 1 are 10ms, 50ms, and 100ms, respectively. Simulation curves of the energy storage controller output power versus the voltage of weak branch 1 are presented. As can be seen from the figures, the method described in this application can effectively suppress voltage fluctuations at each node under impulsive loads, ensuring the stability of the distribution network.

[0042] like Figure 14 , Figure 15 As shown, this embodiment of the invention provides a distribution network voltage fluctuation control device that considers communication time delay. The device embodiment can be implemented through software, hardware, or a combination of both. From a hardware perspective, as... Figure 14 The diagram shown is a hardware architecture diagram of a computing device for a power distribution network voltage fluctuation control device that considers communication time delay, provided in an embodiment of the present invention. (Except for...) Figure 14 In addition to the processor, memory, network interface, and non-volatile memory shown, the computing device in the embodiment may also include other hardware, such as a forwarding chip responsible for processing packets. Taking software implementation as an example, such as... Figure 15 As shown, a device in a logical sense is formed by the CPU of the computing device in which it is located reading the corresponding computer program from the non-volatile memory into the memory for execution.

[0043] Please refer to Figure 15 This invention provides a distribution network voltage fluctuation control device that considers communication time delay, used to implement any of the above methods. The device includes: The first modeling unit 1500 is used to uniformly model the communication time delay between the cooperative controller and each local energy storage controller, and allocate it to the power allocation stage to obtain a power allocation small-signal model with time delay. The second modeling unit 1502 is used to construct the state-space model of the energy storage converter. Unified unit 1504 is used to unify the small-signal model of power distribution and the state-space model of energy storage converter into a common reference coordinate system to obtain the state equations of the whole system. Control unit 1506 is used to perform voltage control of the distribution network based on the state equations of the entire system.

[0044] In some implementations, the first modeling unit 1500 is used to perform the following operations: Construct the state-space model of the collaborative controller; The state-space model of the cooperative controller is linearized to obtain its linearized small-signal model; Using the second-order Pade approximation, the collected voltage information is transmitted to the delay link in the local energy storage controller through the communication line for equivalent processing, resulting in the state-space equation of the equivalent delay element. Linearizing the state-space equation of the equivalent post-delay element yields a small-signal model of power allocation with time delay.

[0045] In some implementations, the power allocation small-signal model with time delay is as follows: In the formula, Let be the equivalent change in the state variable of the time-delay element in the weak branch m. The change in the state variable of the time-delay element in the weak branch m; This represents the equivalent change in power signal in the weak branch m after the communication delay; , These represent the changes in active power and reactive power in the weak branch m after the communication delay, respectively. Communication delay for the weak branch m; , , , These are intermediate parameters.

[0046] In some implementations, the state-space model of the energy storage converter includes: a phase-locked loop model, a power control model, a current inner loop model, and a filter model.

[0047] In some implementations, the overall system state equations are: In the formula, This represents the equivalent change in the state variables of the entire system within the weak branch m. The change in the state variables of the entire system in the weak branch m; , , , These are the coefficient matrices of the weak branch m; This represents the equivalent change in current in the weak branch m. This represents the change in voltage in the weak branch m.

[0048] In some implementations, voltage control of the distribution network is based on the overall system state equations, including: Solve the state equations of the entire system to obtain the system's eigenvalues; The voltage value of the distribution network is adjusted based on the trajectory of the characteristic value change with the communication time delay.

[0049] It should be noted that the distribution network voltage fluctuation control device considering communication delay provided in the above embodiments is only an example of the division of the above functional modules. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the distribution network voltage fluctuation control device considering communication delay provided in the above embodiments and the distribution network voltage fluctuation control method embodiment considering communication delay belong to the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0050] Embodiments of this application also provide a computer device, please refer to... Figure 15 The computer device includes a processor and a memory, the memory storing at least one instruction, at least one program, code set or instruction set, the at least one instruction, at least one program, code set or instruction set being loaded and executed by the processor to implement the power distribution network voltage fluctuation control method considering communication delay provided in the above-described method embodiments.

[0051] Embodiments of this application also provide a computer-readable storage medium storing at least one instruction, at least one program, code set, or instruction set, wherein the at least one instruction, at least one program, code set, or instruction set is loaded and executed by a processor to implement the power distribution network voltage fluctuation control method considering communication delay provided in the above-described method embodiments.

[0052] Embodiments of this application also provide a computer program product, which includes a computer program. A processor of a computer device reads the computer program from a computer-readable storage medium and executes the computer program, causing the computer device to perform the distribution network voltage fluctuation control method considering communication delay as described in any of the above embodiments.

[0053] For ease of description, the above systems or devices are described separately as various modules or units based on their functions. Of course, in implementing this application, the functions of each unit can be implemented in one or more software and / or hardware components.

[0054] As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of this application.

[0055] Finally, it should be noted that in this document, relational terms such as first, second, third, and fourth are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0056] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A method for controlling voltage fluctuations in a distribution network considering communication time delay, characterized in that, The method is applied to a distributed photovoltaic distribution network, wherein the distribution network includes at least a coordinated controller and multiple weak branches, each of which is connected to an impulsive load and an energy storage converter, and each energy storage converter corresponds to a local energy storage controller; the method includes: The communication delay between the collaborative controller and each of the local energy storage controllers is modeled in a unified manner and allocated to the power allocation stage to obtain a power allocation small-signal model with time delay. Construct a state-space model of the energy storage converter; By unifying the power distribution small-signal model and the state-space model of the energy storage converter into a common reference coordinate system, the state equations of the entire system are obtained. Voltage control of the distribution network is performed based on the state equations of the entire system.

2. The method according to claim 1, characterized in that, The step of uniformly modeling the communication time delay between the cooperative controller and each of the local energy storage controllers and allocating it to the power allocation stage to obtain a power allocation small-signal model with time delay includes: Construct the state-space model of the cooperative controller; The state-space model of the cooperative controller is linearized to obtain its linearized small-signal model; Using the second-order Pade approximation, the collected voltage information is transmitted to the delay link in the local energy storage controller through the communication line for equivalent processing, resulting in the state-space equation of the equivalent delay element. Linearizing the state-space equation of the equivalent post-delay element yields a small-signal model of power allocation with time delay.

3. The method according to claim 2, characterized in that, The small-signal model for power allocation with time delay is as follows: In the formula, Let be the equivalent change in the state variable of the time-delay element in the weak branch m. The change in the state variable of the time-delay element in the weak branch m; This represents the equivalent change in power signal in the weak branch m after the communication delay; , These represent the changes in active power and reactive power in the weak branch m after the communication delay, respectively. Communication delay for the weak branch m; , , , These are intermediate parameters.

4. The method according to claim 1, characterized in that, The state-space model of the energy storage converter includes: a phase-locked loop model, a power control model, a current inner loop model, and a filter model.

5. The method according to claim 1, characterized in that, The state equations of the entire system are as follows: In the formula, This represents the equivalent change in the state variables of the entire system within the weak branch m. The change in the state variables of the entire system in the weak branch m; , , , These are the coefficient matrices of the weak branch m; This represents the equivalent change in current in the weak branch m. This represents the change in voltage in the weak branch m.

6. The method according to claim 1, characterized in that, The voltage control of the distribution network based on the overall system state equation includes: Solve the state equations of the entire system to obtain the system eigenvalues; The voltage value of the distribution network is adjusted based on the trajectory of the characteristic value change with the communication time delay.

7. A distribution network voltage fluctuation control device considering communication time delay, characterized in that, The apparatus for implementing the method according to any one of claims 1-6 comprises: The first modeling unit is used to uniformly model the communication time delay between the cooperative controller and each of the local energy storage controllers, and allocate it to the power allocation stage to obtain a power allocation small-signal model with time delay. The second modeling unit is used to construct the state-space model of the energy storage converter. A unified unit is used to unify the power distribution small-signal model and the state-space model of the energy storage converter into a common reference coordinate system to obtain the state equations of the entire system. The control unit is used to perform voltage control on the distribution network based on the overall system state equation.

8. A computer device, characterized in that, The computer device includes a memory and a processor. The memory is used to store computer programs, and the processor is used to execute the computer programs stored in the memory to implement the steps of the method according to any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, which, when executed by a processor, implements the steps of the method described in any one of claims 1-6.

10. A computer program product, characterized in that, Includes a computer program, which, when executed by a processor, implements the steps of the method according to any one of claims 1-6.

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