A power transmission and distribution network coordinated emergency voltage control method and system

Abstract

The application provides a power transmission and distribution network coordinated emergency voltage control method and system, comprising: obtaining wide-area measurement data, calculating generator reactive power margin, when the generator reactive power margin is lower than a set value, including an active power distribution network into power transmission network level control, and calculating reactive power demand of the power transmission network on each active power distribution network; judging whether the reactive power margin of the active power distribution network meets the reactive power demand; if yes, taking the difference between the total photovoltaic output of the power distribution network and the reactive power output support of the active power distribution network and the reactive power demand of the power transmission network as the target, calculating the reactive power output support of the active power distribution network; otherwise, the reactive power output support of the active power distribution network is the reactive power margin of the active power distribution network; applying the reactive power output support of the active power distribution network to the power transmission network, judging whether the load bus voltage meets the preset requirement, if yes, stopping the emergency voltage control; otherwise, returning to calculate the generator reactive power margin until the preset requirement is met. The voltage stability of the power transmission and distribution network is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of smart grid, and particularly relates to a power transmission and distribution network coordinated emergency voltage control method and system. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] With the distributed access of renewable energy such as wind power and photovoltaic power into the power distribution network, the power distribution network gradually changes from the traditional passive receiving-end system to an active system containing distributed power generation and microgrid, and the coordination with the power transmission network is increasingly valued. The power distribution network with distributed power sources can flexibly adjust its reactive power demand to improve the reactive power reserve and the voltage level of the power transmission network. Due to the geographical distribution characteristics of the distributed power sources, if they are properly coordinated, the distributed power generation units can provide more flexible and localized reactive power support at a lower cost compared with the reactive power equipment installed on the power transmission network.

[0004] At the same time, the volatility and uncertainty of renewable energy accessed into the power distribution network pose great challenges to the dispatch between the transmission and distribution, and the increase of the penetration rate of distributed power generation units will also cause reverse power flow, leading to the voltage uplift or even over-limit of the busbar on the power transmission side. In this context, the voltage of the power transmission network and the power distribution network is no longer decoupled, and the dispatch of the high-proportion renewable energy power grid will change from the focus on the power transmission network to the coordinated operation of the power grid at all levels under the widely intelligent foundation. SUMMARY

[0005] In order to solve the technical problems existing in the background art, the present application provides a power transmission and distribution network coordinated emergency voltage control method and system, which can improve the voltage stability of the power transmission and distribution network by including the reactive power resources in the active power distribution network into the voltage control process of the power transmission network through online rolling optimization and feedback correction.

[0006] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0007] The first aspect of the present application provides a power transmission and distribution network coordinated emergency voltage control method, which comprises:

[0008] Obtaining wide-area measurement data, calculating the generator reactive power margin, when the generator reactive power margin is lower than the set value, including the active power distribution network into the power transmission network level control, and calculating the reactive power demand of the power transmission network to each active power distribution network;

[0009] Determine whether the reactive power margin of the active distribution network meets the reactive power demand; if it does, calculate the reactive power support of the active distribution network with the goal of minimizing the total photovoltaic output of the distribution network and minimizing the difference between the reactive power support of the active distribution network and the reactive power demand of the transmission network; otherwise, the reactive power support of the active distribution network is the reactive power margin of the active distribution network.

[0010] The reactive power output of the active distribution network is applied to the transmission network. It is determined whether the load bus voltage meets the preset requirements. If so, the emergency voltage control is stopped; otherwise, the generator reactive power margin is calculated until the load bus voltage meets the preset requirements.

[0011] Furthermore, the calculation of the reactive power demand of the transmission network on each active distribution network aims to minimize voltage deviation and control costs.

[0012] Furthermore, before calculating the generator reactive power margin, it is necessary to determine whether to activate emergency voltage control. Specifically, when the transmission network level detects that the minimum AC bus voltage is below a threshold through wide-area measurement, the transmission network level control is activated.

[0013] Furthermore, the reactive power margin of the active distribution network is the sum of the products of the maximum reactive power output and reactive power sensitivity of all photovoltaic systems in the active distribution network without changing the active power.

[0014] Furthermore, the reactive power sensitivity is the ratio of the reactive power change at the connection point between the power transmission network and the active distribution network to the photovoltaic reactive power output change.

[0015] Furthermore, the constraints for calculating the reactive power output support of the active distribution network include: the voltage of the active distribution network is between the upper and lower limits; the active power of each photovoltaic unit is greater than zero; and the maximum allowable operating power of the photovoltaic unit is 1.1 times the rated power.

[0016] A second aspect of the present invention provides a power transmission and distribution network coordinated emergency voltage control system, comprising:

[0017] The reactive power demand calculation module is configured to: acquire wide-area measurement data, calculate generator reactive power margin, and when the generator reactive power margin is lower than the set value, incorporate the active distribution network into the transmission network level control and calculate the reactive power demand of the transmission network on each active distribution network.

[0018] The reactive power output support calculation module is configured to: determine whether the reactive power margin of the active distribution network meets the reactive power demand; if it does, calculate the reactive power output support of the active distribution network with the goal of minimizing the total photovoltaic output of the distribution network and minimizing the difference between the reactive power output support of the active distribution network and the reactive power demand of the transmission network; otherwise, the reactive power output support of the active distribution network is the reactive power margin of the active distribution network.

[0019] The coordination control module is configured to: apply reactive power support from the active distribution network to the transmission network, determine whether the load bus voltage meets the preset requirements, and if so, stop emergency voltage control; otherwise, return to calculate the generator reactive power margin until the load bus voltage meets the preset requirements.

[0020] Furthermore, it also includes a control startup module, which is configured to initiate transmission network level control when the minimum AC bus voltage is below a threshold via wide-area measurement.

[0021] A third aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method for coordinated emergency voltage control in a power transmission and distribution network.

[0022] A fourth aspect of the present invention provides a computer device including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of a power transmission and distribution network coordinated emergency voltage control method as described above.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] This invention provides a coordinated emergency voltage control method for power transmission and distribution networks. It takes into account the impact of active distribution networks on the voltage stability of the power transmission network system, makes full use of the flexibility of active distribution networks in power regulation, and incorporates active distribution networks as controllable resources into the emergency voltage control of the power transmission network. This enhances the robustness of the power transmission network and active distribution networks and improves the voltage stability of the power transmission network and active distribution networks under faults and disturbances.

[0025] This invention provides a coordinated emergency voltage control method for power transmission and distribution networks. By predicting the trajectory of the control target variable within a finite time domain and solving the optimal control sequence, it solves a quadratic programming problem that optimizes the control target within the time domain. This method enables coordinated optimization control between the power transmission network and the active distribution network, thereby improving the voltage stability of the power transmission network and the active distribution network under faults and disturbances.

[0026] This invention provides a method for coordinated emergency voltage control of power transmission and distribution networks. It takes into account the reactive power margin of active distribution networks and fully considers the voltage support capability of active distribution networks in the optimized control of power transmission networks, ensuring that active distribution networks can effectively participate in emergency voltage control of power transmission networks in the event of a voltage emergency. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0028] Figure 1 This is a flowchart of the emergency voltage control method for power transmission and distribution networks according to Embodiment 1 of the present invention;

[0029] Figure 2 This is a diagram of the coordinated emergency voltage control structure for power transmission and distribution networks according to Embodiment 1 of the present invention;

[0030] Figure 3 This is a schematic diagram of the photovoltaic power feasible region according to Embodiment 1 of the present invention;

[0031] Figure 4(a) is a wiring diagram of a simulation system of an active power distribution network in Embodiment 1 of the present invention;

[0032] Figure 4(b) is a wiring diagram of the active power distribution network according to Embodiment 1 of the present invention;

[0033] Figure 5 This is a graph showing the change in voltage of the weak bus after a system fault in the example system of Embodiment 1 of the present invention when no control is applied.

[0034] Figure 6 This is a graph showing the change in voltage of the weak busbar before and after a system fault after the implementation of the emergency voltage control method for power transmission and distribution networks according to Embodiment 1 of the present invention.

[0035] Figure 7 This is a graph showing the reactive power variation at the common connection point with the transmission network in the No. 2 and No. 4 active distribution networks of Embodiment 1 of the present invention. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0037] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0038] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0039] Example 1

[0040] This embodiment provides a method for coordinated emergency voltage control in power transmission and distribution networks, such as... Figure 2As shown, for a transmission network system containing multiple active distribution networks, it is difficult to precisely control a single distributed generation unit (DGU) in the active distribution network at the transmission network level. Moreover, the active distribution network has its own control strategy. Therefore, it is necessary to coordinate voltage control between the two. The control objectives of the transmission network (i.e., the transmission system operator, TSO) are to minimize voltage deviation and control cost, while the control objectives of the active distribution network (i.e., the distribution system operator, DSO) are to minimize the deviation between reactive power support and reactive power demand issued by the transmission network and to minimize the change in total reactive power of photovoltaics in the active distribution network. In each round of time-domain rolling optimization, the transmission network issues a reactive power demand command to the active distribution network, and the active distribution network returns the reactive power support status.

[0041] This embodiment provides a method for coordinated emergency voltage control in power transmission and distribution networks, such as... Figure 1 As shown, the specific steps include:

[0042] Step 1: Based on the initial value information of the power transmission system, calculate the trajectory sensitivity of each bus voltage and the sensitivity of each control quantity to the bus voltage at the lowest voltage point by combining time-domain simulation. The active distribution network is included in the control quantity, and the bus voltage sensitivity at its common connection point with the power transmission network is calculated. Based on the operating status of each distributed generation unit of the distribution system, calculate the maximum reactive power support that the active distribution network can provide.

[0043] Specifically, initial values ​​for the transmission network system and active distribution network system are calculated based on wide-area measurement data. Based on online synchronous measurement data such as voltage vectors and power injection vectors at each load node provided by the wide-area measurement system, the system admittance matrix and initial values ​​for each state variable are calculated.

[0044] Specifically, the AC power grid operating parameters that need to be determined by the measurement system include the voltage and power vectors of each generator node, load node, and transmission-distribution common connection node, as well as the admittance matrix Y of the AC network. ac The measured parameters of the active distribution network include the rated power of distributed photovoltaic (PV); the current active and reactive power of distributed PV; and the voltage and power vectors of the load nodes in the active distribution network.

[0045] Step 2: Determine whether to activate the rolling time-domain optimized emergency voltage control of the power transmission network based on the lowest voltage point of the power transmission system;

[0046] Specifically, the transmission and distribution system is modeled, and time-domain simulations are performed using the implicit trapezoidal integral method and the Newton-Raphson method, based on the transmission and distribution system model, to predict the system voltage output trajectory. The Jacobian matrix obtained from the time-domain simulation is used to calculate the trajectory sensitivity of each AC control variable of the transmission and distribution system to the load bus voltage.

[0047] Describing the distribution system model using differential-algebraic equations:

[0048] A power system model can be represented by a set of differential-algebraic equations:

[0049]

[0050] 0 = g(x,y,λ)

[0051] Where x represents the system's state variable, y is an algebraic variable, and λ is a parameter variable.

[0052] The trajectory sensitivity of each bus voltage and the voltage sensitivity of the bus at the transmission-distribution common coupling point are calculated. On the AC system side, the active distribution network system is treated as a special load, and the steady-state power flow equations for AC system bus l and the bus k connected to the active distribution network are modified as follows:

[0053]

[0054] Where ΔP and ΔQ are the error column vectors of active power and reactive power respectively in the power flow calculation process; P s and Q s These represent the net active and reactive power injected into the generator and load at the corresponding nodes, respectively; P dc and Q dc The active and reactive power injected into the common connection bus connected to the active distribution network; V and δ are the AC bus voltage amplitude and phase angle, respectively; G and B are the conductance and susceptance of the corresponding elements of the node admittance matrix, respectively.

[0055] By iteratively solving the differential-algebraic equations of the above power transmission and distribution system model using the implicit trapezoidal rule and Newton's method, commonly used in time-domain simulation, the voltage trajectory of the power transmission and distribution system can be obtained. During the simulation, the voltage trajectory sensitivity is calculated using the system's Jacobian matrix. The linearized expression for the system voltage and control quantity under power transmission network voltage control is as follows:

[0056]

[0057] Where k represents the corresponding control quantity at time t k The value at time; Predict the trajectory of voltage changes; The control quantity applied to the system; For voltage pair Trajectory sensitivity.

[0058] like Figure 3 As shown, in an active power distribution network, a model is constructed for distributed photovoltaic (PV) systems, establishing a PV operating power domain. The maximum allowable operating power of the PV system is 1.1 times its rated power. The mathematical expression is:

[0059]

[0060] Specifically, when the transmission network level detects that the minimum AC bus voltage is below the threshold of 0.95 pu through wide-area measurement, the transmission network level control is initiated.

[0061] Step 3: Based on dynamic simulation, monitor the current reactive power margin of the generator in real time and determine whether the active distribution network is included in the control variables of rolling time-domain optimization;

[0062] Specifically, the system acquires wide-area measurement data, calculates the reactive power margin of the system's generators based on the wide-area measurement data, and decides whether to include the active distribution network in the control variables.

[0063] The generator reactive power margin is calculated based on wide-area measurement data. When the generator reactive power margin is higher than the set value, the transmission network-level control does not include active distribution network-level control quantities; the two levels of control quantities are independent of each other, and there is no control conflict. When the generator reactive power margin is lower than the set value, in order to ensure that the transmission network level has sufficient control quantities, the active distribution network-level control quantities are incorporated into the system control, that is, the active distribution network is incorporated into the transmission network-level control.

[0064] Step 4: Based on the transmission network voltage control objective, with the goals of minimizing voltage deviation and minimizing control cost, solve for the control scheme of each control variable participating in the transmission network level control, i.e., solve for the reactive power demand of the transmission network on each active distribution network, and send the optimized reactive power demand command to the distribution network; after receiving the reactive power demand command sent by the transmission network, the active distribution network checks whether its own reactive power margin meets the requirements of the transmission network command. If the requirements are met, the active distribution network provides reactive power output support, i.e., with the goal of minimizing the total photovoltaic output of the distribution network and minimizing the difference between the reactive power output support of the active distribution network and the reactive power demand of the transmission network, the reactive power output support of the active distribution network is calculated; if the requirements cannot be met, the active distribution network provides maximum reactive power output support, i.e., the reactive power output support of the active distribution network is the reactive power margin of the active distribution network.

[0065] Specifically, the coordinated emergency voltage control of the transmission and distribution network, considering the voltage support capability of the active distribution network, is divided into two levels of coordinated control: transmission network-level control and active distribution network-level control. Based on trajectory sensitivity, the system input-output relationship is locally linearized, and a model prediction quadratic programming model for coordinated voltage control is constructed. This model solves the quadratic programming problem of the coordinated emergency voltage control system of the transmission and distribution network, considering the voltage support capability of the active distribution network, and obtains the optimal control sequence of the control variables.

[0066] Transmission network level control:

[0067] In the rolling time-domain optimization process, trajectory sensitivity is used to linearize the system, transforming the nonlinear rolling time-domain optimization control problem into a quadratic programming problem for a linear system, which exhibits strong robustness to model errors and environmental disturbances. The reactive power sensitivity of each control variable to voltage is calculated using trajectory sensitivity, thereby establishing the relationship between the reactive power of each control variable and the target voltage deviation. Simultaneously, optimization is performed with the goal of minimizing voltage deviation and control cost to obtain the specific reactive power output of each control variable, the specific expression of which is:

[0068]

[0069] st

[0070]

[0071] The objective function J is divided into two parts: the minimum AC node voltage deviation and the control cost, with corresponding weighting coefficients ω and ω, respectively. ac and ω k ,i ; This is the voltage reference value. It is the lowest AC node bus voltage before control is applied at time k-1. To control the changing quantities, including generator terminal voltage, parallel capacitors, on-load tap-changing transformers, and reactive power Q in the active distribution network. req Changes in the control variable, control change Adding this to the original control quantity gives the sent control quantity, which is the third expression of the constraint. The prediction step size and control step size of the model predictive control are N, respectively. p N c And N p ≥N c ; To determine the trajectory sensitivity of the control quantity u at time k. The values ​​of each state variable are represented by the subscripts max and min, which indicate the upper and lower limits of the variable.

[0072] Active distribution network level control:

[0073] Upon receiving reactive power control commands from the transmission network, the system coordinates the output of each distributed photovoltaic (PV) photovoltaic unit to meet the commands as much as possible while ensuring its own operational status. To better meet the reactive power demands of the transmission network, the reactive power margin of the distribution network is first assessed. The reactive power margin of an active distribution network is the sum of the products of the maximum reactive power output and reactive power sensitivity of all PV units in the network, without changing their active power output. The formula for calculating the reactive power margin of the distribution network is:

[0074]

[0075] in, Let N be the reactive power margin of the i-th distribution network. pv Let Q be the number of photovoltaic cells in the i-th distribution network. j.max Let S be the maximum reactive power output of the j-th photovoltaic cell without changing its active power. j Let be the reactive power sensitivity of the j-th photovoltaic system; the reactive power sensitivity is the ratio of the change in reactive power at the connection point between the transmission network and the active distribution network to the change in photovoltaic reactive power output, and the calculation method is as follows:

[0076]

[0077] The calculation uses the perturbation method, ΔQ j Let ΔQ be the change in the j-th photovoltaic reactive power output. prv It is the change in reactive power at the connection point between the transmission network and the distribution network, that is, the amount of reactive power that the photovoltaic power generation can provide to the transmission network for every unit of reactive power output.

[0078] when At that time, the reactive power reserve of the distribution network is sufficient, and the objective function is:

[0079]

[0080] Among them, Q req Q represents the reactive power demand sent from the transmission network to the distribution network. prv Q provides reactive power support from the distribution network to the transmission network. j For the reactive power output of the j-th photovoltaic cell; ω dn ω is the weighting coefficient for reactive power deviation. pv The photovoltaic output weighting coefficient of the distribution network is as follows: Since photovoltaics at different locations in the distribution network play different supporting roles in the transmission network, the optimization objective of the distribution network is to meet the received reactive power demand while prioritizing the participation of highly sensitive photovoltaics in control, thereby minimizing the total photovoltaic output of the distribution network.

[0081] The constraints for calculating the reactive power support of an active distribution network include: the voltage of the active distribution network is between its upper and lower limits; the active power of each photovoltaic (PV) unit is greater than zero; and the maximum allowable operating power of the PV units is 1.1 times their rated power. Specific constraints are as follows:

[0082] st

[0083]

[0084]

[0085] Among them, u d For the distribution network voltage, its upper and lower limits are respectively u- d At the same time, the output constraint of the photovoltaic inverter itself is added.

[0086] when At this time, the active power distribution network provides maximum reactive power output support, that is... And return the supporting information to the upper layer.

[0087] Step 5: Apply reactive power support from the active distribution network to the transmission network. After applying control, check whether the load bus voltage meets the preset requirements. If yes, stop the next round of time-domain rolling optimization; otherwise, return to calculate the generator reactive power margin, i.e., return to step 3, until the load bus voltage meets the preset requirements.

[0088] (1) Apply the control quantities of the solved system-level optimal control sequence and the active distribution network-level optimal control quantities to the transmission and distribution system;

[0089] (2) The time window enters the sampling interval of the next sampling moment, and the voltage level of each load bus is measured again;

[0090] (3) If the load bus voltage meets all requirements, exit the coordinated control; otherwise, return to step 3 and repeatedly correct the control deviation caused by the prediction model error and environmental interference until the voltage amplitude meets the requirements.

[0091] This invention considers the impact of active distribution networks on the voltage stability of AC systems, fully leverages the rapid adjustment characteristics of distributed generation units in active distribution networks to maintain the safe and stable voltage of transmission and distribution systems, incorporates the reactive power coordination control of active distribution networks into the voltage stability control of transmission networks, and designs different control schemes based on the reactive power margin of generators, considering the reactive power margin of active distribution networks to provide reasonable support to the transmission network, and designs a two-level coordination strategy for transmission and distribution to improve the voltage stability of the system.

[0092] The Nordic32 example system with source distribution network shown in Figures 4(a) and 4(b) is simulated. The centralized loads in Bus 1041, Bus 1042, Bus 1043, Bus 1044, and Bus 1045 are expanded into a 6-node distribution network system. At the same time, three photovoltaics are connected to each distribution network, accounting for 40% of the total load demand of the distribution network.

[0093] The system load adopts an exponential self-recovering load model. At t=5s, generator g5 in the central region trips due to a fault. Simultaneously, one of the five interconnection lines from the central to the south, line 4032-4044, experiences a line break fault. This line carries 22% of the total active power and 10% of the reactive power transmitted from the north to the central region. Due to the significant active and reactive power deficits in the central region, the OLTC's attempt to restore voltage will further reduce the system voltage. Figure 5 This indicates that without emergency control measures, the system will experience voltage collapse at t=189s; Figure 6This indicates that after the implementation of the transmission and distribution network coordinated emergency voltage control method based on rolling time-domain optimization provided by the present invention, voltage instability was detected at t=20s, and the control started coordinated control at the transmission network level and the active distribution network level. After three rolling optimization controls, the load bus voltage recovered to the control target value of 0.95pu or higher. Figure 7 The changes in reactive power output at the connection point between the transmission network and the active distribution network during this process are illustrated. It can be seen that the reactive power output of the active distribution network effectively supports the transmission network. Therefore, this invention considers the participation of the active distribution network in voltage stability control, coordinating and optimizing the control quantities of the active distribution network and the transmission network during control, and using model predictive control methods to coordinate and allocate the reactive power support capacity of the active distribution network. This invention improves the voltage stability of transmission and distribution systems containing active distribution networks.

[0094] Example 2

[0095] This embodiment provides a coordinated emergency voltage control system for power transmission and distribution networks, which specifically includes the following modules:

[0096] The control startup module is configured to initiate transmission network level control when the minimum AC bus voltage is below a threshold as measured by wide-area measurement.

[0097] The reactive power demand calculation module is configured to: acquire wide-area measurement data, calculate generator reactive power margin, and when the generator reactive power margin is lower than the set value, incorporate the active distribution network into the transmission network level control and calculate the reactive power demand of the transmission network on each active distribution network.

[0098] The reactive power output support calculation module is configured to: determine whether the reactive power margin of the active distribution network meets the reactive power demand; if it does, calculate the reactive power output support of the active distribution network with the goal of minimizing the total photovoltaic output of the distribution network and minimizing the difference between the reactive power output support of the active distribution network and the reactive power demand of the transmission network; otherwise, the reactive power output support of the active distribution network is the reactive power margin of the active distribution network.

[0099] The coordination control module is configured to: apply reactive power support from the active distribution network to the transmission network, determine whether the load bus voltage meets the preset requirements, and if so, stop emergency voltage control; otherwise, return to calculate the generator reactive power margin until the load bus voltage meets the preset requirements.

[0100] It should be noted that each module in this embodiment corresponds one-to-one with each step in Embodiment 1, and their specific implementation processes are the same, so they will not be repeated here.

[0101] Example 3

[0102] This embodiment provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of a power transmission and distribution network coordinated emergency voltage control method as described in Embodiment 1 above.

[0103] Example 4

[0104] This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps in the coordinated emergency voltage control method for power transmission and distribution networks as described in Embodiment 1 above.

[0105] 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 hardware embodiments, software embodiments, or embodiments combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0106] 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 device that provides the functions specified in one or more boxes.

[0107] 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 instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0108] 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 boxesFigure 1 The steps of the function specified in one or more boxes.

[0109] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0110] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for coordinated emergency voltage control in power transmission and distribution networks, characterized in that, include: Wide-area measurement data is acquired, and the reactive power margin of the generator is calculated. When the reactive power margin of the generator is lower than the set value, the active distribution network is incorporated into the transmission network level control, and the reactive power demand of the transmission network on each active distribution network is calculated. The current reactive power margin of the generator is monitored in real time based on dynamic simulation, and it is determined whether the active distribution network is included in the rolling time-domain optimized control quantity. The calculation of the reactive power demand of the transmission network on each active distribution network aims to minimize voltage deviation and minimize control cost. Determine whether the reactive power margin of the active distribution network meets the reactive power demand; if it does, calculate the reactive power support of the active distribution network with the goal of minimizing the total photovoltaic output of the distribution network and minimizing the difference between the reactive power support of the active distribution network and the reactive power demand of the transmission network. Otherwise, the reactive power output of the active distribution network is the reactive power margin of the active distribution network. The constraints for calculating the reactive power support of the active distribution network include: the voltage of the active distribution network is between the upper and lower limits; the active power of each photovoltaic unit is greater than zero; and the maximum allowable operating power of the photovoltaic unit is 1.1 times the rated power. The reactive power output of the active distribution network is applied to the transmission network. It is determined whether the load bus voltage meets the preset requirements. If so, the emergency voltage control is stopped; otherwise, the generator reactive power margin is calculated until the load bus voltage meets the preset requirements.

2. The method for coordinated emergency voltage control in a power transmission and distribution network as described in claim 1, characterized in that, Before calculating the generator reactive power margin, it is necessary to determine whether to activate emergency voltage control. Specifically, when the transmission network level detects that the minimum AC bus voltage is below a threshold through wide-area measurement, the transmission network level control is activated.

3. The method for coordinated emergency voltage control in a power transmission and distribution network as described in claim 1, characterized in that, The reactive power margin of the active distribution network is the sum of the products of the maximum reactive power output and reactive power sensitivity of all photovoltaic systems in the active distribution network without changing the active power.

4. The method for coordinated emergency voltage control in a power transmission and distribution network as described in claim 3, characterized in that, The reactive power sensitivity is the ratio of the reactive power change at the connection point between the power transmission network and the active distribution network to the photovoltaic reactive power output change.

5. A coordinated emergency voltage control system for power transmission and distribution networks, characterized in that, include: The reactive power demand calculation module is configured to: acquire wide-area measurement data, calculate generator reactive power margin, and when the generator reactive power margin is lower than a set value, incorporate the active distribution network into the transmission network level control and calculate the reactive power demand of the transmission network on each active distribution network; monitor the current reactive power margin of the generator in real time based on dynamic simulation and determine whether the active distribution network is included in the rolling time-domain optimized control quantity; the calculation of the reactive power demand of the transmission network on each active distribution network aims to minimize voltage deviation and minimize control cost. The reactive power output support calculation module is configured to: determine whether the reactive power margin of the active distribution network meets the reactive power demand; if it does, calculate the reactive power output support of the active distribution network with the goal of minimizing the total photovoltaic output of the distribution network and minimizing the difference between the reactive power output support of the active distribution network and the reactive power demand of the transmission network. Otherwise, the reactive power output of the active distribution network is the reactive power margin of the active distribution network. The constraints for calculating the reactive power support of the active distribution network include: the voltage of the active distribution network is between the upper and lower limits; the active power of each photovoltaic unit is greater than zero; and the maximum allowable operating power of the photovoltaic unit is 1.1 times the rated power. The coordination control module is configured to: apply reactive power support from the active distribution network to the transmission network, determine whether the load bus voltage meets the preset requirements, and if so, stop emergency voltage control; otherwise, return to calculate the generator reactive power margin until the load bus voltage meets the preset requirements.

6. A coordinated emergency voltage control system for power transmission and distribution networks as described in claim 5, characterized in that, It also includes a control startup module, which is configured to initiate transmission network level control when the minimum AC bus voltage is below a threshold via wide-area measurement.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps in the method for coordinated emergency voltage control of a power transmission and distribution network as described in any one of claims 1-4.

8. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps in the power transmission and distribution network coordinated emergency voltage control method as described in any one of claims 1-4.

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