Reactive power control method and system for new energy station after direct current blocking fault

Abstract

The invention provides a reactive power control method and system for a new energy station after a direct current blocking fault. The reactive power control method comprises the steps of obtaining reactive power output data of the new energy station after the direct current blocking fault; obtaining a reactive power reference value of the new energy station by using a pre-constructed reactive power control model according to the reactive power output data; performing reactive power control on the new energy station according to the reactive power reference value; wherein the reactive power control model is constructed by taking maximization of reactive power reserve of the new energy station as a target and taking a transient voltage fluctuation degree constraint, a transient off-network risk degree constraint and an adjustable reactive power output limit constraint as constraint conditions; according to the method, the reactive power backup of the new energy station is maximized, and the constraint conditions are combined, so that the reactive power support capability of the new energy station after the direct-current locking fault can be fully excavated, dynamic reactive power support resources with considerable capacity are formed, the voltage collapse phenomenon caused by overlarge voltage fluctuation can be prevented, and the voltage stability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power system control, and in particular to a reactive power control method and system for a new energy station after a DC blocking fault. Background Art

[0002] At present, in some load center areas, UHV DC is put into operation intensively, replacing a large number of conventional thermal power units at the receiving end, and the voltage support capacity of the receiving end power grid has declined, and the voltage stability problem has become increasingly prominent. The primary energy and load are distributed inversely. The construction of long-distance, large-capacity UHV AC and DC transmission projects is an effective means to meet the needs of clean energy delivery and load center power supply. In the UHV DC receiving end power grid, DC replaces conventional units on a large scale. The two have opposite reactive voltage regulation characteristics when the system voltage is reduced. The concentrated DC feed-in causes the system voltage regulation capacity to decline; secondly, a large amount of reactive power needs to be absorbed during faults such as DC commutation failure. Large-scale DC feed-in leads to increasingly prominent problems in the system's dynamic voltage stability.

[0003] At the same time, the scale of installed capacity of new energy sources in the DC area near the receiving power grid is increasing. Compared with conventional units, their single-machine reactive power regulation capability is weaker, and their reactive output capacity is affected by the grid voltage, resulting in a decrease in the reactive support capacity of new energy stations after a DC lockout failure. Summary of the invention

[0004] In order to solve the problem of reduced reactive power support capacity of a new energy station after a DC blocking fault occurs in the prior art, the present invention proposes a reactive power control method for a new energy station after a DC blocking fault, comprising:

[0005] Obtain reactive power output data of new energy stations after DC blocking failure;

[0006] According to the reactive power output data, a reactive power reference value of the new energy station is obtained by using a pre-built reactive power control model;

[0007] According to the reactive power reference value, reactive power control is performed on the new energy station;

[0008] Among them, the reactive power control model aims to maximize the reactive power reserve of the new energy station, and is constructed with transient voltage fluctuation degree constraint, transient grid-off risk constraint and adjustable reactive power output limit constraint as constraint conditions.

[0009] Optionally, the reactive power control model includes the following construction process:

[0010] Obtaining a reactive power output curve of the new energy station;

[0011] Determine the reactive power reserve of the new energy station according to the reactive power output curve, and construct an objective function with the goal of maximizing the reactive power reserve of the new energy station;

[0012] Based on the objective function and pre-built constraints, a reactive power control model is obtained;

[0013] The constraints include: transient voltage fluctuation degree constraint, transient grid-off risk constraint and adjustable reactive power output limit constraint.

[0014] Optionally, determining the reactive power reserve of the new energy station according to the reactive power output curve includes:

[0015] According to the reactive power output curve, the maximum reactive power output of the new energy station is obtained;

[0016] The reactive reserve of the new energy station is obtained by calculating the difference between the maximum reactive output value of the new energy station and the reactive output value of the new energy station at each moment.

[0017] Optionally, the expression corresponding to the objective function is as follows:

[0018]

[0019] Among them, Q OF represents the reactive power reserve of the new energy station; m represents the total number of new energy stations; j = 1…m; Q jmax represents the maximum reactive power output of the new energy station j; Q j Represents the reactive power output of the new energy station j at the current moment.

[0020] Optionally, the transient voltage fluctuation degree constraint includes the following construction process:

[0021] Obtain voltage curves of key nodes in the power grid after a DC blocking fault;

[0022] Calculating the transient voltage fluctuation degree of the key node according to the voltage curve of the key node;

[0023] According to the transient voltage fluctuation degree of the key node, determine whether the key node has voltage weakness, and if so, use a preset fluctuation coefficient calculation formula to obtain the transient voltage fluctuation degree influence coefficient of the key node;

[0024] According to the transient voltage fluctuation degree influence coefficient, the transient voltage fluctuation degree constraint of the key node is constructed.

[0025] Optionally, judging whether the key node has voltage weakness according to the transient voltage fluctuation degree of the key node includes:

[0026] When the transient voltage fluctuation degree of the key node is less than a preset transient voltage fluctuation threshold, it is determined that the key node has voltage weakness.

[0027] Optionally, the calculation formula corresponding to the transient voltage fluctuation degree is as follows:

[0028]

[0029] Among them, δ u,i Indicates the fluctuation degree of transient voltage u at key node i; t s Indicates the starting time point of the integral calculation; t cr represents the total duration of the integral calculation; u(t) represents the transient voltage of the key node at time t; u cr Indicates the set voltage threshold; u N Indicates rated voltage; t a Indicates the start time of DC blocking; t b Indicates the end time of the transient process.

[0030] Optionally, the fluctuation coefficient is calculated as follows:

[0031]

[0032] Among them, ψ u,ij Q represents the influence coefficient of the reactive power change of the new energy station j on the fluctuation degree of the transient voltage u of the key node i with weak voltage; j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of the new energy station j; δ u,i Indicates the fluctuation degree of transient voltage u at key node i.

[0033] Optionally, the expression corresponding to the transient voltage fluctuation degree constraint is as follows:

[0034]

[0035] Among them, δ u,i represents the fluctuation degree of transient voltage u at key node i; m represents the total number of new energy stations; j = 1…m; ψ u,ij ΔQ represents the influence coefficient of the reactive power change of the new energy station j on the fluctuation degree of the transient voltage u of the key node i with weak voltage; j Represents the reactive power change of the new energy station j; ρ u Indicates the preset fluctuation threshold of transient voltage u.

[0036] Optionally, the transient off-grid risk constraint and the adjustable reactive power output limit constraint include the following construction process:

[0037] Obtaining a voltage curve of the grid connection point of the new energy station after a DC blocking fault;

[0038] Calculating the transient off-grid risk of the new energy station according to the voltage curve of the grid connection point;

[0039] According to the transient off-grid risk degree of the new energy station, determine whether the new energy station has off-grid risk, and if so, obtain the transient off-grid risk impact coefficient of the new energy station using a preset off-grid risk calculation formula;

[0040] According to the transient off-grid risk impact coefficient of the new energy station, a transient off-grid risk degree constraint and an adjustable reactive power output limit constraint of the new energy station are constructed.

[0041] Optionally, the calculation formula corresponding to the transient off-grid risk of the new energy station is as follows:

[0042]

[0043] Among them, γ upcc,k represents the transient off-grid risk of the new energy station k; t s Indicates the starting time point of the integral calculation; t cn represents the total time for calculating the risk of grid disconnection; u(t) represents the transient voltage of the node at time t; u cn Indicates the operating voltage threshold of the new energy station; u N Indicates rated voltage; t a Indicates the start time of DC blocking; t b Indicates the end time of the transient process.

[0044] Optionally, the off-network risk calculation formula is as follows:

[0045]

[0046] Among them, ε upcc,kj Q represents the impact coefficient of reactive power change of new energy station j on transient grid-off risk of new energy station k with grid-off risk; j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of the new energy station j; γ upcc,k Represents the transient off-grid risk of new energy station k.

[0047] Optionally, the transient off-grid risk constraint is expressed as follows:

[0048]

[0049] Among them, γ upcc,krepresents the transient off-grid risk of renewable energy station k; m represents the total number of renewable energy stations; j = 1…m; ε upcc,kj ΔQ represents the impact coefficient of reactive power change of new energy station j on the transient grid-off risk of new energy station k with grid-off risk; j Represents the reactive power change of new energy station j.

[0050] Optionally, the expression corresponding to the adjustable reactive output limit constraint is as follows:

[0051]

[0052] Among them, Q j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of new energy station j; P j represents the current active power of the new energy station j; S j Represents the apparent power of new energy station j.

[0053] Based on the same inventive concept, the present invention also provides a reactive power control system for a new energy station after a DC blocking fault, comprising:

[0054] The data acquisition module is used to obtain the reactive power output data of the new energy station after the DC blocking fault;

[0055] A model output module, used to obtain a reactive power reference value of the new energy station according to the reactive output data using a pre-built reactive power control model;

[0056] A reactive power control module, used for performing reactive power control on the new energy station according to the reactive power reference value;

[0057] Among them, the reactive power control model in the model output module is aimed at maximizing the reactive power reserve of the new energy station, and is constructed with transient voltage fluctuation degree constraint, transient off-grid risk constraint and adjustable reactive power output limit constraint as constraint conditions.

[0058] Optionally, the model output module includes:

[0059] An output information acquisition submodule, used to obtain the reactive power output curve of the new energy station;

[0060] An objective function construction submodule, for determining the reactive reserve of the new energy station according to the reactive output curve, and constructing an objective function with the goal of maximizing the reactive reserve of the new energy station;

[0061] A control model building submodule, used to obtain a reactive power control model based on the objective function and pre-built constraints;

[0062] The constraints include: transient voltage fluctuation degree constraint, transient grid-off risk constraint and adjustable reactive power output limit constraint.

[0063] Optionally, the objective function construction submodule includes:

[0064] A maximum value extraction unit, used to obtain the maximum reactive power output of the new energy station according to the reactive power output curve;

[0065] The reactive reserve calculation unit is used to calculate the difference between the maximum reactive output value of the new energy station and the reactive output value of the new energy station at each moment, so as to obtain the reactive reserve value of the new energy station.

[0066] Optionally, the expression corresponding to the objective function in the objective function construction submodule is as follows:

[0067]

[0068] Among them, Q OF represents the reactive power reserve of the new energy station; m represents the total number of new energy stations; j = 1…m; Q jmax represents the maximum reactive power output of the new energy station j; Q j Represents the reactive power output of the new energy station j at the current moment.

[0069] Optionally, the control model building submodule includes:

[0070] A node curve acquisition unit, used to acquire voltage curves of key nodes in the power grid after a DC blocking fault;

[0071] A node fluctuation calculation unit, used to calculate the transient voltage fluctuation degree of the key node according to the voltage curve of the key node;

[0072] A node influence fluctuation unit is used to determine whether the key node has voltage weakness according to the transient voltage fluctuation degree of the key node, and if so, obtain the transient voltage fluctuation degree influence coefficient of the key node using a preset fluctuation coefficient calculation formula;

[0073] The fluctuation constraint construction unit is used to construct the transient voltage fluctuation degree constraint of the key node according to the transient voltage fluctuation degree influence coefficient.

[0074] Optionally, the node influence fluctuation unit is specifically used for:

[0075] When the transient voltage fluctuation degree of the key node is less than a preset transient voltage fluctuation threshold, it is determined that the key node has voltage weakness.

[0076] Optionally, the calculation formula corresponding to the transient voltage fluctuation degree in the node fluctuation calculation unit is as follows:

[0077]

[0078] Among them, δ u,i Indicates the fluctuation degree of transient voltage u at key node i; t s Indicates the starting time point of the integral calculation; t cr represents the total duration of the integral calculation; u(t) represents the transient voltage of the key node at time t; u cr Indicates the set voltage threshold; u N Indicates rated voltage; t a Indicates the start time of DC blocking; t b Indicates the end time of the transient process.

[0079] Optionally, the calculation formula of the fluctuation coefficient in the node impact fluctuation unit is as follows:

[0080]

[0081] Among them, ψ u,ij Q represents the influence coefficient of the reactive power change of the new energy station j on the fluctuation degree of the transient voltage u of the key node i with weak voltage; j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of the new energy station j; δ u,i Indicates the fluctuation degree of transient voltage u at key node i.

[0082] Optionally, the expression corresponding to the transient voltage fluctuation degree constraint in the node fluctuation calculation unit is as follows:

[0083]

[0084] Among them, δ u,i represents the fluctuation degree of transient voltage u at key node i; m represents the total number of new energy stations; j = 1…m; ψ u,ij ΔQ represents the influence coefficient of the reactive power change of the new energy station j on the fluctuation degree of the transient voltage u of the key node i with weak voltage; j Represents the reactive power change of the new energy station j; ρ u Indicates the preset fluctuation threshold of transient voltage u.

[0085] Optionally, the control model building submodule further includes:

[0086] A station curve acquisition unit, used to acquire a voltage curve of the grid connection point of the new energy station after a DC blocking fault;

[0087] A risk calculation unit, configured to calculate the transient off-grid risk of the new energy station according to the voltage curve of the grid connection point;

[0088] A grid-off risk calculation unit, used to determine whether the new energy station has a grid-off risk according to the transient grid-off risk degree of the new energy station, and if so, obtain the transient grid-off risk impact coefficient of the new energy station using a preset grid-off risk calculation formula;

[0089] The station constraint construction unit is used to construct the transient off-grid risk degree constraint and the adjustable reactive power output limit constraint of the new energy station according to the transient off-grid risk impact coefficient of the new energy station.

[0090] Optionally, the calculation formula corresponding to the transient off-grid risk of the new energy station in the risk calculation unit is as follows:

[0091]

[0092] Among them, γ upcc,k represents the transient off-grid risk of the new energy station k; t s Indicates the starting time point of the integral calculation; t cn represents the total time for calculating the risk of grid disconnection; u(t) represents the transient voltage of the node at time t; u cn Indicates the operating voltage threshold of the new energy station; u N Indicates rated voltage; t a Indicates the start time of DC blocking; t b Indicates the end time of the transient process.

[0093] Optionally, the off-line risk calculation formula in the off-line risk calculation unit is as follows:

[0094]

[0095] Among them, ε upcc,kj Q represents the impact coefficient of reactive power change of new energy station j on transient grid-off risk of new energy station k with grid-off risk; j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of the new energy station j; γ upcc,k Represents the transient off-grid risk of new energy station k.

[0096] Optionally, the expression of the transient off-grid risk constraint in the station constraint construction unit is as follows:

[0097]

[0098] Among them, γ upcc,krepresents the transient off-grid risk of renewable energy station k; m represents the total number of renewable energy stations; j = 1…m; ε upcc,kj ΔQ represents the impact coefficient of reactive power change of new energy station j on the transient grid-off risk of new energy station k with grid-off risk; j Represents the reactive power change of new energy station j.

[0099] Optionally, the expression corresponding to the adjustable reactive output limit constraint in the station constraint construction unit is as follows:

[0100]

[0101] Among them, Q j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of new energy station j; P j represents the current active power of the new energy station j; S j Represents the apparent power of new energy station j.

[0102] In another aspect, the present invention further provides an electronic device, comprising: at least one processor and a memory; the memory and the processor are connected via a bus;

[0103] The memory is used to store one or more programs;

[0104] When the one or more programs are executed by the at least one processor, the reactive power control method of a new energy station after a DC blocking fault as described above is implemented.

[0105] On the other hand, the present invention further provides a computer-readable storage medium having an execution program stored thereon, and when the execution program is executed, the reactive power control method of a new energy station after a DC locking fault as described above is implemented.

[0106] Compared with the prior art, the present invention has the following beneficial effects:

[0107] The present invention provides a reactive power control method and system for a new energy station after a DC locking fault, comprising: obtaining reactive output data of the new energy station after a DC locking fault; obtaining a reactive power reference value of the new energy station according to the reactive output data by using a pre-constructed reactive control model; performing reactive power control on the new energy station according to the reactive power reference value; wherein the reactive control model is constructed with the goal of maximizing the reactive reserve of the new energy station and with the constraints of transient voltage fluctuation degree, transient off-grid risk degree and adjustable reactive output limit; the present application performs reactive power control on the new energy station after a DC locking fault by using the reactive power reference value obtained by the reactive control model constructed with the constraint conditions with the goal of maximizing reactive reserve, which can fully tap the reactive support capacity of the new energy station after the DC locking fault, form a dynamic reactive support resource with considerable capacity, and is conducive to improving the reactive support capacity of the new energy station after a DC locking fault, and can prevent the voltage collapse phenomenon caused by excessive voltage fluctuation, and enhance the voltage stability of the new energy station. BRIEF DESCRIPTION OF THE DRAWINGS

[0108] Figure 1 It is a flow chart of a reactive power control method of a new energy station after a DC blocking fault provided by the present invention;

[0109] Figure 2 It is a schematic diagram of the execution flow of a reactive power control method of a new energy station after a DC blocking fault in a specific embodiment of the present invention;

[0110] Figure 3 It is a modified Nordic32 simulation example system in a specific embodiment of the present invention;

[0111] Figure 4 It is a voltage curve of the main power grid nodes in the vicinity after DC blocking before control is applied in a specific embodiment of the present invention;

[0112] Figure 5 It is the voltage curve of the grid connection point of the main renewable energy station in the vicinity after the DC blocking before the control is applied in the specific embodiment of the present invention;

[0113] Figure 6 is a voltage curve of a main power grid node in the vicinity after DC blocking after control is applied in a specific embodiment of the present invention;

[0114] Figure 7 It is the voltage curve of the grid connection point of the main new energy station in the vicinity after DC blocking after control is applied in the specific embodiment of the present invention;

[0115] Figure 8 It is a schematic diagram of the structure of a reactive power control system of a new energy station after a DC blocking fault provided by the present invention;

[0116] Fig. 9 The present invention provides a schematic structural diagram of an electronic device. DETAILED DESCRIPTION

[0117] The present invention proposes a reactive power control method for a new energy station after a DC blocking fault. The specific implementation manner of the present invention is further described in detail below with reference to the accompanying drawings.

[0118] Embodiment 1:

[0119] The present invention provides a reactive power control method for a new energy station after a DC blocking fault, the flow chart of which is as follows: Figure 1 As shown, including:

[0120] Step 1: Obtain reactive power output data of the new energy station after the DC blocking fault;

[0121] Step 2: Based on the reactive power output data, the reactive power reference value of the new energy station is obtained by using the pre-built reactive power control model;

[0122] Step 3: Perform reactive power control on the new energy station according to the reactive power reference value;

[0123] Among them, the reactive power control model aims to maximize the reactive power reserve of new energy stations, and is constructed with transient voltage fluctuation constraints, transient grid-off risk constraints and adjustable reactive power output limit constraints as constraints.

[0124] Generally, when the scale of installed capacity of new energy in the DC area near the receiving power grid increases, its single-machine reactive power regulation capability is weaker than that of conventional units, and its reactive power output capacity is affected by the grid voltage. At this time, if the reactive support capacity of new energy is not integrated and tapped, the stability of the grid voltage will decrease. In order to deal with the voltage control problem occurring near the receiving-end power grid after the high-voltage direct current transmission system is locked, the present invention first obtains the reactive power output data of the new energy station after the DC lockout fault, and based on the reactive power output data, fully explores the reactive power support capability of the new energy station near the receiving end, performs reactive power control on the new energy station after the DC lockout fault, and supports the voltage of the power grid after the DC fault. By way of example, the reactive power output data may include the following information: time series, reactive power value, fault information and power grid status information; wherein the time series may include a timestamp and a time interval, the timestamp is used to record the time point of reactive power output, usually in seconds, minutes or hours, and the time interval is used to describe the frequency of change of reactive power output; the reactive power value may include: reactive power output and reactive power demand; the fault information may include: fault time, fault type and fault duration; the power grid status information may include: voltage level, current level and power grid frequency.

[0125] In one implementation, the reactive power control model may include the following construction process:

[0126] Obtain reactive power output curve of new energy stations;

[0127] According to the reactive power output curve, the reactive power reserve of the new energy station is determined, and the objective function is constructed with the goal of maximizing the reactive power reserve of the new energy station;

[0128] Based on the objective function and pre-built constraints, a reactive power control model is obtained;

[0129] For example, the constraint conditions may include: a transient voltage fluctuation degree constraint, a transient grid-trip risk constraint, and an adjustable reactive power output limit constraint.

[0130] In this implementation, the process of determining the reactive power reserve of the new energy station according to the reactive power output curve may include:

[0131] According to the reactive power output curve, the maximum reactive power output of the new energy station is obtained;

[0132] The reactive reserve of the new energy station is obtained by calculating the difference between the maximum reactive output of the new energy station and the reactive output of the new energy station at each moment.

[0133] For example, the expression corresponding to the above objective function can be as follows:

[0134]

[0135] Among them, Q OF represents the reactive power reserve of the new energy station; m represents the total number of new energy stations; j = 1…m; Q jmax represents the maximum reactive power output of the new energy station j; Q j Represents the reactive power output of the new energy station j at the current moment.

[0136] In this implementation, the present invention can provide sufficient reactive support when the system experiences voltage fluctuations by maximizing the reactive reserve of the new energy station, thereby enhancing voltage stability, preventing the occurrence of voltage collapse events, and improving the reliability of the power system; by optimizing the reactive output curve and reactive reserve, the degree of voltage fluctuation can be reduced during the transient process of the system, and the transient voltage fluctuation degree constraint ensures that the voltage will not fluctuate excessively when the system is disturbed, thereby protecting sensitive equipment from damage; the transient off-grid risk constraint ensures that when the system fails, the new energy station can maintain connection with the power grid, avoid unnecessary off-grid events, and improve the continuous power supply capacity of the system; the adjustable reactive output limit constraint can ensure that the new energy station will not exceed its own reactive adjustment capacity while providing reactive support, which is conducive to the rational use of reactive resources and avoids equipment damage or shortening of service life due to excessive use. The above technical scheme can improve the performance of the power system in many aspects, including voltage stability, transient response capability, continuous power supply capability and equipment utilization rate, by optimizing the reactive power management of the new energy station, which is not only conducive to the safe and stable operation of the power system, but also provides technical support for large-scale access to renewable energy.

[0137] In one implementation, the above transient voltage fluctuation degree constraint includes the following construction process:

[0138] Obtain voltage curves of key nodes in the power grid after a DC blocking fault;

[0139] According to the voltage curve of the key node, calculate the transient voltage fluctuation degree of the key node;

[0140] According to the transient voltage fluctuation degree of the key node, determine whether the key node has voltage weakness. If so, use the preset fluctuation coefficient calculation formula to obtain the transient voltage fluctuation degree influence coefficient of the key node;

[0141] According to the transient voltage fluctuation degree influence coefficient, the transient voltage fluctuation degree constraint of key nodes is constructed.

[0142] In this implementation, the process of judging whether a key node has a voltage weakness according to the transient voltage fluctuation degree of the key node may include:

[0143] When the transient voltage fluctuation degree of the key node is less than a preset transient voltage fluctuation threshold (for example, the transient voltage fluctuation threshold can be set to 0.67), it is determined that the key node has voltage weakness;

[0144] When the transient voltage fluctuation degree of the key node is not less than the above-mentioned transient voltage fluctuation threshold, it is determined that the key node does not have voltage weakness;

[0145] In this implementation, the voltage curves of key nodes in the power grid after a DC lockout fault can be obtained in the following way: a new energy station model including wind turbines, photovoltaic arrays, inverters and other components is constructed using power system simulation software (such as MATLAB or Simulink, etc.), appropriate simulation parameters are set according to the simulation accuracy requirements and time range, a DC lockout fault is simulated, and key nodes in the power grid are selected, such as substation buses, important load nodes, etc., the voltage values ​​of these nodes during the simulation process are recorded, usually expressed in per-unit values, and the voltage curves of these nodes after the DC lockout fault are plotted. By constructing a transient voltage fluctuation degree constraint, the present invention can more accurately control the voltage fluctuation of key nodes, prevent the voltage from excessively fluctuating in the transient process after the fault, and help maintain the stability of the voltage and reduce the risk of voltage collapse; by calculating the transient voltage fluctuation degree of the key nodes, and judging whether the node has voltage weakness according to the preset transient voltage fluctuation threshold, the weak links in the system can be more accurately identified, which is conducive to taking targeted measures to strengthen the voltage stability of these nodes; by analyzing the transient voltage fluctuation degree of the key nodes and constructing the constraint conditions accordingly, the reactive power allocation strategy can be optimized to ensure that there is sufficient reactive power support during the fault to maintain the voltage level. Therefore, for new energy stations, optimizing the transient voltage fluctuation degree can improve its grid connection capability and stability, which is conducive to the access of more new energy power generation and promotes the development and utilization of clean energy. The above technical scheme of the present invention constructs the transient voltage fluctuation degree constraint through a series of steps, which can improve the performance of the power system in many aspects, including voltage stability, system reliability, response speed and economy, which is of great significance for ensuring the safe and stable operation of the power system, and also promotes the large-scale grid connection and development of new energy.

[0146] For example, the calculation formula corresponding to the above transient voltage fluctuation degree can be as follows:

[0147]

[0148] Among them, δ u,i Indicates the fluctuation degree of transient voltage u at key node i; t s Indicates the starting time point of the integral calculation; t cr represents the total duration of the integral calculation; u(t) represents the transient voltage of the key node at time t; u cr Indicates the set voltage threshold; u N Indicates rated voltage; t a Indicates the start time of DC blocking; t b Indicates the end time of the transient process.

[0149] For example, the above volatility coefficient calculation formula can be as follows:

[0150]

[0151] Among them, ψ u,ij It represents the influence coefficient of reactive power change of new energy station j on the fluctuation degree of transient voltage u of key node i with weak voltage; Q j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of the new energy station j; δ u,i Indicates the fluctuation degree of transient voltage u at key node i.

[0152] For example, the expression corresponding to the above transient voltage fluctuation degree constraint can be as follows:

[0153]

[0154] Among them, δ u,i represents the fluctuation degree of transient voltage u at key node i; m represents the total number of new energy stations; j = 1…m; ψ u,ij ΔQ represents the influence coefficient of reactive power change of new energy station j on the fluctuation degree of transient voltage u of key node i with weak voltage; j Represents the reactive power change of the new energy station j; ρ u Indicates the preset fluctuation threshold of transient voltage u.

[0155] In one implementation, the above-mentioned transient off-grid risk constraint and adjustable reactive power output limit constraint may include the following construction process:

[0156] Obtain the voltage curve of the grid connection point of the new energy station after the DC blocking fault;

[0157] Calculate the transient off-grid risk of the new energy station based on the voltage curve of the grid connection point;

[0158] According to the transient off-grid risk degree of the new energy station, determine whether the new energy station has the risk of off-grid. If yes, use the preset off-grid risk calculation formula to obtain the transient off-grid risk impact coefficient of the new energy station;

[0159] According to the transient off-grid risk impact coefficient of the new energy station, the transient off-grid risk constraint and adjustable reactive power output limit constraint of the new energy station are constructed;

[0160] In this implementation, if the calculated value of the transient off-grid risk of the new energy station is less than 0, the new energy station is deemed to have off-grid risk;

[0161] In this implementation, by calculating the transient off-grid risk and setting corresponding constraints, it is possible to effectively prevent the new energy station from being off-grid after a DC locking fault, which is conducive to maintaining the stable operation of the system and reducing the system disturbance caused by off-grid; by real-time monitoring of the voltage curve of the grid connection point and calculating the transient off-grid risk according to the voltage curve, the potential off-grid risk can be discovered in time. Once the off-grid risk is found, preventive measures can be taken, such as adjusting the reactive power output, thereby reducing the occurrence of actual off-grid events. Therefore, the present invention can ensure that the new energy station will not exceed its adjustment capacity while providing reactive support by constructing an adjustable reactive output limit constraint, which is conducive to the reasonable allocation of reactive resources, avoiding equipment overload or damage due to improper reactive power regulation, and enhancing fault recovery capability. The above technical scheme of the present invention can improve the performance of the power system in many aspects, including system stability, response speed, fault recovery capability and economy, by constructing transient off-grid risk constraints and adjustable reactive output limit constraints, which is of great significance for ensuring the safe and stable operation of the power system, and also promotes the large-scale grid connection and development of new energy.

[0162] For example, the calculation formula corresponding to the transient off-grid risk of the above-mentioned new energy station can be as follows:

[0163]

[0164] Among them, γ upcc,k represents the transient off-grid risk of the new energy station k; t s Indicates the starting time point of the integral calculation; t cn represents the total time for calculating the risk of grid disconnection; u(t) represents the transient voltage of the node at time t; u cn Indicates the operating voltage threshold of the new energy station; u N Indicates rated voltage; t a Indicates the start time of DC blocking; t b Indicates the end time of the transient process.

[0165] For example, the above-mentioned off-network risk calculation formula can be as follows:

[0166]

[0167] Among them, ε upcc,kj Q represents the impact coefficient of reactive power change of new energy station j on transient grid-off risk of new energy station k with grid-off risk; j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of the new energy station j; γ upcc,k Represents the transient off-grid risk of new energy station k.

[0168] For example, the above transient off-grid risk constraint can be expressed as follows:

[0169]

[0170] Among them, γ upcc,k represents the transient off-grid risk of renewable energy station k; m represents the total number of renewable energy stations; j = 1…m; ε upcc,kj ΔQ represents the impact coefficient of reactive power change of new energy station j on the transient grid-off risk of new energy station k with grid-off risk; j Represents the reactive power change of new energy station j.

[0171] For example, the expression corresponding to the above adjustable reactive power output limit constraint can be as follows:

[0172]

[0173] Among them, Q j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of new energy station j; P j represents the current active power of the new energy station j; S j Represents the apparent power of new energy station j.

[0174] The present invention aims at the problem of reduced reactive supporting capacity of new energy stations after a DC locking fault in the prior art, and proposes a reactive control method for new energy stations after a DC locking fault. Reactive control is performed on the new energy stations after the DC locking fault through a reactive power reference value obtained by a reactive control model constructed with the goal of maximizing reactive reserve. This is beneficial to improving the mining of reactive supporting capacity of multiple new energy stations with transient voltage characteristics of the power grid after the DC locking fault, making full use of the reactive output capacity of the new energy stations themselves, and reducing the investment in reactive compensation devices of the power grid. In addition, when performing reactive support for multiple new energy stations after a DC locking fault, the present invention not only takes into account the transient voltage control and stability of the entire network after the DC fault, but also reduces the risk of the new energy power station itself being disconnected from the grid, and preserves as much of the total reactive margin of the new energy stations as possible, which is beneficial to enhancing the reactive supporting capacity of the system after another fault occurs.

[0175] Embodiment 2:

[0176] A reactive power control method for a new energy station after a DC blocking fault provided by the present invention is described with a specific embodiment. The specific flow chart is as follows: Figure 2 As shown, the steps include:

[0177] S101: Update the running status of the simulation example system;

[0178] S102: Simulate and obtain voltage curve data of main power grid nodes and new energy station connection points in the vicinity after a DC blocking fault;

[0179] S103: Calculate the node transient voltage fluctuation degree and the transient grid-off risk of the new energy station according to the voltage curve data;

[0180] S104: Calculate the transient voltage fluctuation degree impact coefficient of the voltage weak node and the transient grid-off risk impact coefficient of the new energy station with grid-off risk;

[0181] S105: Constructing constraint conditions and objective functions to solve the optimization result of reactive power output of new energy stations;

[0182] S106: Update the reactive power reference value of the new energy station according to the optimization result.

[0183] The simulation experiment of this embodiment is based on the original Nordic32 simulation example system, and the simulation example system is modified as follows: the busbars 4044-4032 are replaced with DC lines, the rated DC transmission power is set to 1000MW, and the generators g6 and g7 near the busbar 4044 of the receiving end converter station are replaced with the new energy stations at the three buses 1042, 1043, and 1045, and the following is obtained: Figure 3 The modified Nordic32 simulation example system shown in the figure includes some key elements, such as wind farms (represented by Wind1, Wind2 and Wind3), generators (generator numbers are represented by g1-g20, which are different power generation units in the system), external equivalents (used to represent equivalent models outside the system), north (used to represent a geographical area of ​​the system, including multiple nodes, generators and wind farms), center (used to represent the core part of the system, which may include important substations or other key equipment), south (used to represent another geographical area in the system, also including multiple nodes, generators and wind farms), and the rest represent bus numbers.

[0184] Specifically, the above step S101 may include:

[0185] Set up the active power of DC transmission in the example system, the active / reactive output of the generator and new energy station, the active / reactive power consumed by the load, and the operating status of other related equipment.

[0186] The above step S102 may include:

[0187] When t=1s, a DC blocking fault is set, and the AC filter of the converter station is removed after a delay of 200ms. The voltage response curve of the node after the DC blocking fault is as follows: Figure 4As shown in the figure (the horizontal axis Time represents time in seconds, the vertical axis Voltage is represented by the unit value pu, and Bus represents the bus in the figure), the voltage response curve of the new energy station grid connection point is as follows Figure 5 shown.

[0188] based on Figure 4 The node voltage response curve data in the above step S103 can be expressed as follows:

[0189]

[0190] Among them, δ u,i Indicates the fluctuation degree of transient voltage u at key node i; t s Indicates the starting time point of the integral calculation; t cr It represents the total duration of the integral calculation, which can be taken as 1s during calculation; u(t) represents the transient voltage of the key node at time t; u cr Indicates the set voltage threshold, which can be taken as 0.75 during calculation; u N Indicates the rated voltage, which is taken as 1.0 during calculation; t a Indicates the start time of DC blocking; t b Indicates the end time of the transient process.

[0191] based on Figure 4 The voltage response curve data of the grid connection point of the new energy station in the above step S103 can be expressed as follows:

[0192]

[0193] Among them, γ upcc,k represents the transient off-grid risk of the new energy station k; t s Indicates the starting time point of the integral calculation; t cn represents the total time for calculating the risk of grid disconnection; u(t) represents the transient voltage of the node at time t; u cn Indicates the operating voltage threshold of the new energy station; u N Indicates rated voltage; t a Indicates the start time of DC blocking; t b Indicates the end time of the transient process.

[0194] The above step S104 may specifically include:

[0195] Transient voltage fluctuation threshold ρ u Set to 0.67, if δ u,i <0.67, then the node is a voltage weak node, and its transient voltage fluctuation degree influence coefficient is calculated as follows:

[0196]

[0197] Among them, ψ u,ij It represents the influence coefficient of reactive power change of new energy station j on the fluctuation degree of transient voltage u of key node i with weak voltage; Q j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of the new energy station j; δ u,i Indicates the fluctuation degree of transient voltage u at key node i.

[0198] If γ upcc,k <0, the new energy station has the risk of grid disconnection, and the transient grid disconnection risk impact coefficient is calculated as follows:

[0199]

[0200] Among them, ε upcc,kj Q represents the impact coefficient of reactive power change of new energy station j on transient grid-off risk of new energy station k with grid-off risk; j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of the new energy station j; γ upcc,k represents the transient off-grid risk of the new energy station k;

[0201] The above step S105 may specifically include:

[0202] The transient voltage fluctuation degree constraint of the voltage weak node is as follows:

[0203]

[0204] Among them, δ u,i represents the fluctuation degree of transient voltage u at key node i; m represents the total number of new energy stations; j = 1…m; ψ u,ij ΔQ represents the influence coefficient of reactive power change of new energy station j on the fluctuation degree of transient voltage u of key node i with weak voltage; j Represents the reactive power change of the new energy station j; Represents the increment of transient voltage fluctuation degree at voltage weak node i after reactive power compensation of all new energy stations.

[0205] The transient off-grid risk constraint of a new energy station with off-grid risk is as follows:

[0206]

[0207] Among them, γ upcc,k represents the transient off-grid risk of renewable energy station k; m represents the total number of renewable energy stations; j = 1…m; εupcc,kj ΔQ represents the impact coefficient of reactive power change of new energy station j on the transient grid-off risk of new energy station k with grid-off risk; j represents the reactive power change of the new energy station j, Represents the transient off-grid risk increment of the new energy station k with off-grid risk after reactive power compensation for all new energy stations.

[0208] The adjustable reactive power output limit constraint of the new energy station is as follows:

[0209]

[0210] Among them, Q j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of new energy station j; P j represents the current active power of the new energy station j; S j Represents the apparent power of new energy station j.

[0211] The expression corresponding to the objective function is as follows:

[0212]

[0213] Among them, Q OF represents the reactive power reserve of the renewable energy station, i.e., the optimization target; m represents the total number of renewable energy stations; j = 1…m; Q jmax represents the maximum reactive power output of the new energy station j; Q j Represents the reactive power output of the new energy station j at the current moment.

[0214] Combined with the constraints, an optimization algorithm (such as linear programming method, genetic algorithm, particle swarm algorithm, gradient descent algorithm, etc.) is used to optimize and solve the objective function to obtain the reactive power reference value of each new energy station;

[0215] The obtained reactive power reference value of the new energy station is sent to each new energy station for storage. When a DC blocking fault occurs, a new reactive power reference value is used for control.

[0216] After adopting this strategy, the voltage response curve of the node after the DC blocking fault is as follows: Figure 6 As shown, the voltage response curve of the grid connection point of the new energy station is as follows Figure 7 Compared with no control, the transient stability of node voltage is effectively improved after adopting this control method, and the two new energy stations that enter low voltage ride-through no longer enter the low voltage ride-through state.

[0217] Therefore, the above specific embodiments can illustrate that the method of the present invention can optimize the reactive output of new energy stations after DC interlocking faults by actively controlling and orderly aggregating a large number of new energy reactive support potentials, fully tap the reactive support capabilities of these new energy stations, and form dynamic reactive support resources with considerable capacity, which is conducive to improving the performance of the power system in many aspects, including voltage stability, system response speed, fault recovery capability and economy. This is of great significance for ensuring the safe and stable operation of the power system, and also promotes the large-scale grid connection and development of new energy. Through real-time data acquisition and rapid calculation, the solution can adjust reactive power in time, effectively respond to emergencies such as DC interlocking faults, and improve the overall stability and reliability of the power system.

[0218] Embodiment 3:

[0219] Based on the same inventive concept, the present invention also provides a reactive power control system for a new energy station after a DC blocking fault, the structural composition diagram is as follows: Figure 8 As shown, including:

[0220] The data acquisition module is used to obtain the reactive power output data of the new energy station after the DC blocking fault;

[0221] The model output module is used to obtain the reactive power reference value of the new energy station based on the reactive power output data and using the pre-built reactive power control model;

[0222] Reactive power control module, used to perform reactive power control on new energy stations according to reactive power reference value;

[0223] Among them, the reactive power control model in the model output module aims to maximize the reactive power reserve of the new energy station, and is constructed with the constraints of transient voltage fluctuation degree, transient grid-off risk and adjustable reactive power output limit.

[0224] In one implementation, the above-mentioned model output module may include:

[0225] The output information acquisition submodule is used to obtain the reactive power output curve of the new energy station;

[0226] The objective function construction submodule is used to determine the reactive power reserve of the new energy station according to the reactive power output curve, and to construct the objective function with the goal of maximizing the reactive power reserve of the new energy station;

[0227] A control model building submodule is used to obtain a reactive power control model based on an objective function and pre-built constraints;

[0228] For example, the constraints in the control model construction submodule may include: transient voltage fluctuation degree constraint, transient grid-off risk constraint and adjustable reactive power output limit constraint.

[0229] In this implementation, the above-mentioned objective function construction submodule may include:

[0230] A maximum value extraction unit is used to obtain the maximum reactive power output of the new energy station according to the reactive power output curve;

[0231] The reactive reserve calculation unit is used to calculate the difference between the maximum reactive output value of the new energy station and the reactive output value of the new energy station at each moment, so as to obtain the reactive reserve value of the new energy station.

[0232] In this implementation, the expression corresponding to the objective function in the above objective function construction submodule can be as follows:

[0233]

[0234] Among them, Q OF represents the reactive power reserve of the new energy station; m represents the total number of new energy stations; j = 1…m; Q jmax represents the maximum reactive power output of the new energy station j; Q j Represents the reactive power output of the new energy station j at the current moment.

[0235] In this implementation, the control model building submodule may include:

[0236] A node curve acquisition unit, used to acquire voltage curves of key nodes in the power grid after a DC blocking fault;

[0237] A node fluctuation calculation unit is used to calculate the transient voltage fluctuation degree of the key node according to the voltage curve of the key node;

[0238] The node influence fluctuation unit is used to determine whether the key node has voltage weakness according to the transient voltage fluctuation degree of the key node. If so, the transient voltage fluctuation degree influence coefficient of the key node is obtained by using a preset fluctuation coefficient calculation formula;

[0239] The fluctuation constraint construction unit is used to construct the transient voltage fluctuation degree constraint of the key node according to the transient voltage fluctuation degree influence coefficient.

[0240] In this implementation, the node influence fluctuation unit can be used to:

[0241] When the transient voltage fluctuation degree of the key node is less than a preset transient voltage fluctuation threshold, it is determined that the key node has voltage weakness.

[0242] For example, the calculation formula corresponding to the transient voltage fluctuation degree in the above-mentioned node fluctuation calculation unit may be as follows:

[0243]

[0244] Among them, δ u,i Indicates the fluctuation degree of transient voltage u at key node i; t s Indicates the starting time point of the integral calculation; t cr represents the total duration of the integral calculation; u(t) represents the transient voltage of the key node at time t; u cr Indicates the set voltage threshold; u N Indicates rated voltage; t a Indicates the start time of DC blocking; t b Indicates the end time of the transient process.

[0245] For example, the calculation formula for the fluctuation coefficient in the above node influence fluctuation unit can be as follows:

[0246]

[0247] Among them, ψ u,ij It represents the influence coefficient of reactive power change of new energy station j on the fluctuation degree of transient voltage u of key node i with weak voltage; Q j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of the new energy station j; δ u,i Indicates the fluctuation degree of transient voltage u at key node i.

[0248] For example, the expression corresponding to the transient voltage fluctuation degree constraint in the above-mentioned node fluctuation calculation unit may be as follows:

[0249]

[0250] Among them, δ u,i represents the fluctuation degree of transient voltage u at key node i; m represents the total number of new energy stations; j = 1…m; ψ u,ij ΔQ represents the influence coefficient of reactive power change of new energy station j on the fluctuation degree of transient voltage u of key node i with weak voltage; j Represents the reactive power change of the new energy station j; ρ u Indicates the preset fluctuation threshold of transient voltage u.

[0251] In one implementation, the control model building submodule may further include:

[0252] A station curve acquisition unit is used to obtain a voltage curve of a grid connection point of a new energy station after a DC blocking fault;

[0253] A risk calculation unit is used to calculate the transient off-grid risk of the new energy station according to the voltage curve of the grid connection point;

[0254] The off-grid risk calculation unit is used to determine whether the new energy station has an off-grid risk according to the transient off-grid risk degree of the new energy station. If yes, the transient off-grid risk impact coefficient of the new energy station is obtained by using a preset off-grid risk calculation formula;

[0255] The station constraint construction unit is used to construct the transient off-grid risk constraint and adjustable reactive power output limit constraint of the new energy station according to the transient off-grid risk impact coefficient of the new energy station.

[0256] For example, the calculation formula corresponding to the transient off-grid risk of the new energy station in the above-mentioned risk calculation unit can be as follows:

[0257]

[0258] Among them, γ upcc,k represents the transient off-grid risk of the new energy station k; t s Indicates the starting time point of the integral calculation; t cn represents the total time for calculating the risk of grid disconnection; u(t) represents the transient voltage of the node at time t; u cn Indicates the operating voltage threshold of the new energy station; u N Indicates rated voltage; t a Indicates the start time of DC blocking; t b Indicates the end time of the transient process.

[0259] For example, the off-network risk calculation formula in the above-mentioned off-network risk calculation unit may be as follows:

[0260]

[0261] Among them, ε upcc,kj Q represents the impact coefficient of reactive power change of new energy station j on transient grid-off risk of new energy station k with grid-off risk; j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of the new energy station j; γ upcc,k Represents the transient off-grid risk of new energy station k.

[0262] For example, the expression of the transient off-grid risk constraint in the above-mentioned station constraint construction unit can be as follows:

[0263]

[0264] Among them, γ upcc,krepresents the transient off-grid risk of renewable energy station k; m represents the total number of renewable energy stations; j = 1…m; ε upcc,kj ΔQ represents the impact coefficient of reactive power change of new energy station j on the transient grid-off risk of new energy station k with grid-off risk; j Represents the reactive power change of new energy station j.

[0265] For example, the expression corresponding to the adjustable reactive output limit constraint in the above-mentioned station constraint construction unit may be as follows:

[0266]

[0267] Among them, Q j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of new energy station j; P j represents the current active power of the new energy station j; S j Represents the apparent power of new energy station j.

[0268] Embodiment 4:

[0269] like Fig. 9 As shown, the present invention also provides an electronic device, which may be a computer device, a single-chip device, an intelligent mobile device, etc. The electronic device in this embodiment may include a processor, a memory, a transceiver component, etc. The memory, the processor, and the transceiver component are connected via a bus; the memory may be used to store an execution program, and an exemplary execution program may include instructions; the processor is used to execute the instructions stored in the memory. The memory may also be used to store data, which may be called and / or modified when the instructions are executed.

[0270] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in a storage medium to implement corresponding method flows or corresponding functions, so as to implement the steps of a reactive power control method for a new energy station after a DC locking fault in the above-mentioned embodiment.

[0271] Embodiment 5:

[0272] Based on the same inventive concept, the present invention also provides a readable storage medium, specifically an electronic device readable storage medium (Memory), which is a memory device in an electronic device for storing programs and data. It is understandable that the storage medium here may include both a built-in storage medium in an electronic device and an extended storage medium supported by the electronic device. The storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by a processor are also stored in the storage space, and these instructions may be one or more execution programs (including program codes). It should be noted that the storage medium here may be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor loads and executes one or more instructions stored in the storage medium, which can implement the steps of a reactive power control method of a new energy station after a DC locking fault in the above embodiment.

[0273] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0274] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0275] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1A function specified in one or more boxes.

[0276] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0277] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the application, but these changes, modifications or equivalent substitutions are all within the protection scope of the claims to be approved.

Claims

1. A reactive power control method for a new energy station after a DC blocking fault, characterized in that: include: Obtain reactive power output data of new energy stations after DC blocking failure; According to the reactive power output data, a reactive power reference value of the new energy station is obtained by using a pre-built reactive power control model; According to the reactive power reference value, reactive power control is performed on the new energy station; Among them, the reactive power control model aims to maximize the reactive power reserve of the new energy station, and is constructed with transient voltage fluctuation degree constraint, transient grid-off risk constraint and adjustable reactive power output limit constraint as constraint conditions.

2. The method according to claim 1, characterized in that The reactive power control model includes the following construction process: Obtaining a reactive power output curve of the new energy station; Determine the reactive power reserve of the new energy station according to the reactive power output curve, and construct an objective function with the goal of maximizing the reactive power reserve of the new energy station; Based on the objective function and pre-built constraints, a reactive power control model is obtained; The constraints include: transient voltage fluctuation degree constraint, transient grid-off risk constraint and adjustable reactive power output limit constraint.

3. The method according to claim 2, characterized in that Determining the reactive power reserve of the new energy station according to the reactive power output curve includes: According to the reactive power output curve, the maximum reactive power output of the new energy station is obtained; The reactive reserve of the new energy station is obtained by calculating the difference between the maximum reactive output value of the new energy station and the reactive output value of the new energy station at each moment.

4. The method according to claim 2, characterized in that The expression corresponding to the objective function is as follows: Among them, Q OF represents the reactive power reserve of the new energy station; m represents the total number of new energy stations; j = 1…m; Q jmax represents the maximum reactive power output of the new energy station j; Q j Represents the reactive power output of the new energy station j at the current moment.

5. The method according to claim 2, characterized in that The transient voltage fluctuation degree constraint includes the following construction process: Obtain voltage curves of key nodes in the power grid after a DC blocking fault; Calculating the transient voltage fluctuation degree of the key node according to the voltage curve of the key node; According to the transient voltage fluctuation degree of the key node, determine whether the key node has voltage weakness, and if so, use a preset fluctuation coefficient calculation formula to obtain the transient voltage fluctuation degree influence coefficient of the key node; According to the transient voltage fluctuation degree influence coefficient, the transient voltage fluctuation degree constraint of the key node is constructed.

6. The method according to claim 5, characterized in that The determining, based on the transient voltage fluctuation degree of the key node, whether the key node has voltage weakness includes: When the transient voltage fluctuation degree of the key node is less than a preset transient voltage fluctuation threshold, it is determined that the key node has voltage weakness.

7. The method according to claim 5 or 6, characterized in that The calculation formula corresponding to the transient voltage fluctuation degree is as follows: Among them, δ u,i Indicates the fluctuation degree of transient voltage u at key node i; t s Indicates the starting time point of the integral calculation; t cr represents the total duration of the integral calculation; u(t) represents the transient voltage of the key node at time t; u cr Indicates the set voltage threshold; u N Indicates rated voltage; t a Indicates the start time of DC blocking; t b Indicates the end time of the transient process.

8. The method according to claim 5, characterized in that The fluctuation coefficient calculation formula is as follows: Among them, ψ u,ij Q represents the influence coefficient of the reactive power change of the new energy station j on the fluctuation degree of the transient voltage u of the key node i with weak voltage; j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of the new energy station j; δ u,i Indicates the fluctuation degree of transient voltage u at key node i.

9. The method according to any one of claims 1 to 5, characterized in that: The expression corresponding to the transient voltage fluctuation degree constraint is as follows: Among them, δ u,i represents the fluctuation degree of transient voltage u at key node i; m represents the total number of new energy stations; j = 1…m; ψ u,ij ΔQ represents the influence coefficient of the reactive power change of the new energy station j on the fluctuation degree of the transient voltage u of the key node i with weak voltage; j Represents the reactive power change of the new energy station j; ρ u Indicates the preset fluctuation threshold of transient voltage u.

10. The method according to claim 2, characterized in that The transient off-grid risk constraint and the adjustable reactive power output limit constraint include the following construction process: Obtaining a voltage curve of the grid connection point of the new energy station after a DC blocking fault; Calculating the transient off-grid risk of the new energy station according to the voltage curve of the grid connection point; According to the transient off-grid risk degree of the new energy station, determine whether the new energy station has off-grid risk, and if so, obtain the transient off-grid risk impact coefficient of the new energy station using a preset off-grid risk calculation formula; According to the transient off-grid risk impact coefficient of the new energy station, a transient off-grid risk degree constraint and an adjustable reactive power output limit constraint of the new energy station are constructed.

11. The method according to claim 10, characterized in that The calculation formula corresponding to the transient off-grid risk of the new energy station is as follows: Among them, γ upcc,k represents the transient off-grid risk of the new energy station k; t s Indicates the starting time point of the integral calculation; t cn represents the total time for calculating the risk of grid disconnection; u(t) represents the transient voltage of the node at time t; u cn Indicates the operating voltage threshold of the new energy station; u N Indicates rated voltage; t a Indicates the start time of DC blocking; t b Indicates the end time of the transient process.

12. The method according to claim 10, characterized in that The off-line risk calculation formula is as follows: Among them, ε upcc,kj Q represents the impact coefficient of reactive power change of new energy station j on transient grid-off risk of new energy station k with grid-off risk; j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of the new energy station j; γ upcc,k Represents the transient off-grid risk of new energy station k.

13. The method according to claim 10, characterized in that The expression of the transient off-grid risk constraint is as follows: Among them, γ upcc,k represents the transient off-grid risk of renewable energy station k; m represents the total number of renewable energy stations; j = 1…m; ε upcc,kj ΔQ represents the impact coefficient of reactive power change of new energy station j on the transient grid-off risk of new energy station k with grid-off risk; j Represents the reactive power change of new energy station j.

14. The method according to claim 10, characterized in that The expression corresponding to the adjustable reactive output limit constraint is as follows: Among them, Q j represents the current reactive power of the new energy station j; ΔQ j Represents the reactive power change of new energy station j; P j represents the current active power of the new energy station j; S j Represents the apparent power of new energy station j.

15. A reactive power control system for a new energy station after a DC blocking fault, characterized in that: include: The data acquisition module is used to obtain the reactive power output data of the new energy station after the DC blocking fault; A model output module, used to obtain a reactive power reference value of the new energy station according to the reactive output data using a pre-built reactive power control model; A reactive power control module, used for performing reactive power control on the new energy station according to the reactive power reference value; Among them, the reactive power control model aims to maximize the reactive power reserve of the new energy station, and is constructed with transient voltage fluctuation degree constraint, transient grid-off risk constraint and adjustable reactive power output limit constraint as constraint conditions.

16. The system of claim 15, wherein: The reactive power control model in the model output module includes the following construction process: Obtaining a reactive power output curve of the new energy station; Determine the reactive power reserve of the new energy station according to the reactive power output curve, and construct an objective function with the goal of maximizing the reactive power reserve of the new energy station; Based on the objective function and pre-built constraints, a reactive power control model is obtained; The constraints include: transient voltage fluctuation degree constraint, transient grid-off risk constraint and adjustable reactive power output limit constraint.

17. An electronic device, characterized in that: include: at least one processor and memory; The memory and the processor are connected via a bus; The memory is used to store one or more programs; When the one or more programs are executed by the at least one processor, a reactive power control method for a new energy station after a DC blocking fault as described in any one of claims 1 to 14 is implemented.

18. A computing device readable storage medium, characterized in that: An execution program is stored thereon, and when the execution program is executed, a reactive power control method for a new energy station after a DC locking fault as described in any one of claims 1 to 14 is implemented.

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