Method and system for determining delivery capacity of new energy alternating current delivery system

Abstract

The invention discloses a new energy AC delivery system delivery capacity determination method and system, and the method comprises the steps: maintaining the total output of a thermal power generating unit / the total output of a new energy unit unchanged in combination with time domain simulation, and increasing the output of the new energy unit / the total output of the thermal power generating unit, so as to change the operation mode of the system, obtaining safety and stability limit points of the system after alternating current N-1 faults in different operation modes; determining a security and stability boundary based on the security and stability limit point, and determining a security and stability constraint interval based on the marking condition of the security and stability limit point and the security and stability boundary; and determining a linear function curve representing the sending capacity of the system, determining the sending capacity of the system based on the condition of the intersection point of the linear function curve and the safety and stability boundary, and determining the constraint type of the intersection point based on the safety and stability constraint interval. The method can accurately determine the sending capacity of the new energy AC delivery system, can be applied to a large-scale new energy grid-connected system, and ensures the safety and stability of new energy AC delivery.

Description

Technical Field

[0001] The present invention relates to the technical field of large power grid stability analysis and control application, and more specifically, to a method and system for determining the transmission capacity of a new energy AC transmission system. Background Art

[0002] With the rapid development of renewable energy power generation, the demand for power transmission is increasing. Large-scale renewable energy transmission over long distances through UHV AC / DC projects has become an important form of power grid construction in my country. Limited by the grid conditions of energy bases, such systems usually have weak grids and insufficient short-circuit capacity, and the transient safety and stability of the system face severe challenges.

[0003] In the AC transmission system of renewable energy, the thermal power startup mode has a significant impact on the transient stability level of the sending-end system. In the thermal power startup mode, the AC channel operates at high power. At this time, channel failure will cause a large flow transfer and energy shock, making the power angle swing of the sending-end unit larger, and prone to transient power angle instability. During the power angle swing, the risk of overvoltage at the renewable energy machine end is becoming increasingly prominent, which can easily cause large-scale disconnection of renewable energy from the grid, threatening the safe and stable operation of the power grid.

[0004] At present, the determination of system transmission capacity mainly considers the power angle stability constraint, and has not yet taken into account the overvoltage safety constraint of the renewable energy generator during the power angle swing process. Therefore, it is urgent to propose a method for determining the system transmission capacity that takes into account both the power angle stability constraint and the overvoltage safety constraint, so as to effectively support the safe and efficient consumption of renewable energy. Summary of the invention

[0005] The present invention proposes a method and system for determining the delivery capacity of a new energy AC delivery system to solve the problem of how to efficiently determine the delivery capacity of the new energy AC delivery system.

[0006] In order to solve the above problem, according to one aspect of the present invention, a method for determining the transmission capacity of a new energy AC transmission system is provided, the method comprising:

[0007] Combined with time domain simulation, the total output of thermal power units / new energy units is maintained unchanged, and the output of new energy units / thermal power units is increased to change the operation mode of the system, and the safety and stability limit points of the system after AC N-1 fault under different operation modes are obtained;

[0008] Determining a safe and stable boundary based on the safe and stable limit point, and determining a safe and stable constraint interval based on the marking of the safe and stable limit point and the safe and stable boundary;

[0009] A linear function curve representing the delivery capacity of the system is determined, the delivery capacity of the system is determined based on the intersection of the linear function curve and the safety and stability boundary, and the type of constraint imposed on the intersection is determined based on the safety and stability constraint interval.

[0010] Preferably, the method further comprises:

[0011] Under different operation modes, the reactive compensation amount in the renewable energy collection station is adjusted to maintain the steady-state renewable energy terminal voltage at 1.00pu before the fault.

[0012] Preferably, the step of obtaining the safety and stability limit point of the system after AC N-1 failure under different operation modes includes:

[0013] Under any operating mode, if the thermal power unit has a power angle instability problem, it is marked as a power angle stability constraint to obtain the power angle stability limit point; if a temporary power frequency overvoltage problem occurs at the new energy machine end, it is marked as an overvoltage safety constraint to obtain the overvoltage safety limit point.

[0014] Preferably, the step of determining the safety and stability constraint interval based on the marking conditions of the safety and stability limit points and the safety and stability boundaries comprises:

[0015] Determining a power angle stability constraint interval based on a line connecting at least a preset number of discrete power angle stability limit points;

[0016] Determining an overvoltage safety constraint interval based on a connection line of at least a preset number of discrete overvoltage safety limit points;

[0017] The interval corresponding to the line connecting the discrete safety and stability limit points outside the power angle stability constraint interval and the overvoltage safety constraint interval is taken as the chaos constraint interval.

[0018] Preferably, the linear function curve is:

[0019] P 火电 =-P 新能源 +P total ,

[0020] Among them, P 火电 is the total thermal power output; P 新能源 Total output for new energy; P total is the system delivery capacity; the slope of the linear function curve is -1, and the intersection with the y-axis is the intercept, i.e. P total .

[0021] Preferably, the delivery capacity of the system is determined based on the intersection of the linear function curve and the safety and stability boundary, and the type of constraint imposed on the intersection is determined based on the safety and stability constraint interval:

[0022] If the linear function curve has only one intersection with the safety and stability boundary, the unit output corresponding to the intersection is the maximum capacity of the system; at this time, if the intersection is located in the power angle stability constraint interval, the system delivery capacity is subject to the power angle stability constraint; if it is located in the overvoltage safety constraint interval, the system delivery capacity is subject to the overvoltage safety constraint; if it is located in the chaos constraint interval, it may be subject to both the power angle stability constraint and the overvoltage safety constraint;

[0023] If the linear function curve has two intersections with the safety and stability boundary, the delivery capacity range for determining the delivery capacity of the system is [b0, b1], the minimum value of the system delivery capacity is b0, and the maximum value is b1; at this time, any point in the closed area formed by the linear function curve and the safety and stability boundary satisfies the system safety and stability constraints; where b0 is the intercept when the linear function curve has two intersections with the safety and stability boundary; b1 is the intercept when the linear function curve has only one intersection with the safety and stability boundary;

[0024] If the linear function curve does not intersect the safety and stability boundary, there is no steady-state operating point corresponding to the system delivery capacity b2; where b2 is the intercept of the linear function curve.

[0025] According to another aspect of the present invention, a system for determining the delivery capacity of a new energy AC delivery system is provided, the system comprising:

[0026] The safety and stability limit calculation unit is used to combine time domain simulation to maintain the total output of thermal power units / new energy units unchanged, increase the output of new energy units / total output of thermal power units, so as to change the operation mode of the system and obtain the safety and stability limit points of the system after AC N-1 fault under different operation modes;

[0027] A safety and stability constraint interval identification unit, used to determine a safety and stability boundary based on the safety and stability limit point, and determine a safety and stability constraint interval based on the marking of the safety and stability limit point and the safety and stability boundary;

[0028] The delivery capacity determination unit is used to determine a linear function curve representing the delivery capacity of the system, determine the delivery capacity of the system based on the intersection of the linear function curve and the safety and stability boundary, and determine the constraint type of the intersection based on the safety and stability constraint interval.

[0029] Preferably, the system further comprises:

[0030] The adjustment unit is used to adjust the reactive compensation amount in the renewable energy collection station under different operation modes to maintain the steady-state renewable energy terminal voltage at 1.00pu before the fault.

[0031] Preferably, the safety and stability limit calculation unit obtains the safety and stability limit point of the system after AC N-1 failure under different operation modes, including:

[0032] Under any operating mode, if the thermal power unit has a power angle instability problem, it is marked as a power angle stability constraint to obtain the power angle stability limit point; if a temporary power frequency overvoltage problem occurs at the new energy machine end, it is marked as an overvoltage safety constraint to obtain the overvoltage safety limit point.

[0033] Preferably, the safety and stability constraint interval identification unit determines the safety and stability constraint interval based on the marking of the safety and stability limit point and the safety and stability boundary, including:

[0034] Determining a power angle stability constraint interval based on a line connecting at least a preset number of discrete power angle stability limit points;

[0035] Determining an overvoltage safety constraint interval based on a connection line of at least a preset number of discrete overvoltage safety limit points;

[0036] The interval corresponding to the line connecting the discrete safety and stability limit points outside the power angle stability constraint interval and the overvoltage safety constraint interval is taken as the chaos constraint interval.

[0037] Preferably, the linear function curve is:

[0038] P 火电 =-P 新能源 +P total ,

[0039] Among them, P 火电 is the total thermal power output; P 新能源 Total output for new energy; P total is the system delivery capacity; the slope of the linear function curve is -1, and the intersection with the y-axis is the intercept, i.e. P total .

[0040] Preferably, the delivery capacity determination unit determines the delivery capacity of the system based on the intersection of the linear function curve and the safety and stability boundary, and determines the type of constraint on the intersection based on the safety and stability constraint interval:

[0041] If the linear function curve has only one intersection with the safety and stability boundary, the unit output corresponding to the intersection is the maximum capacity of the system; at this time, if the intersection is located in the power angle stability constraint interval, the system delivery capacity is subject to the power angle stability constraint; if it is located in the overvoltage safety constraint interval, the system delivery capacity is subject to the overvoltage safety constraint; if it is located in the chaos constraint interval, it may be subject to both the power angle stability constraint and the overvoltage safety constraint;

[0042] If the linear function curve has two intersections with the safety and stability boundary, the delivery capacity range for determining the delivery capacity of the system is [b0, b1], the minimum value of the system delivery capacity is b0, and the maximum value is b1; at this time, any point in the closed area formed by the linear function curve and the safety and stability boundary satisfies the system safety and stability constraints; where b0 is the intercept when the linear function curve has two intersections with the safety and stability boundary; b1 is the intercept when the linear function curve has only one intersection with the safety and stability boundary;

[0043] If the linear function curve does not intersect the safety and stability boundary, there is no steady-state operating point corresponding to the system delivery capacity b2; where b2 is the intercept of the linear function curve.

[0044] Based on another aspect of the present invention, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any step of a method for determining the delivery capacity of a new energy AC delivery system.

[0045] According to another aspect of the present invention, the present invention provides an electronic device, including:

[0046] The computer-readable storage medium described above; and

[0047] One or more processors are used to execute the program in the computer-readable storage medium.

[0048] The present invention provides a method and system for determining the delivery capacity of a new energy AC transmission system, including: combining time domain simulation, maintaining the total output level of thermal power units / new energy units unchanged, increasing the output of new energy units / total output of thermal power units, so as to change the operation mode of the system, and obtaining the safety and stability limit point of the system after AC N-1 failure under different operation modes; determining the safety and stability boundary based on the safety and stability limit point, and determining the safety and stability constraint interval based on the marking of the safety and stability limit point and the safety and stability boundary; determining a linear function curve representing the delivery capacity of the system, determining the delivery capacity of the system based on the intersection of the linear function curve and the safety and stability boundary, and determining the constraint type of the intersection based on the safety and stability constraint interval. The present invention can efficiently and accurately determine the delivery capacity of a new energy AC transmission system, and can be applied to large-scale new energy grid-connected systems to ensure the safety and stability of new energy AC transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0050] Figure 1 It is a flow chart of a method 100 for determining the transmission capacity of a new energy AC transmission system according to an embodiment of the present invention;

[0051] Figure 2 A schematic diagram of a new energy AC transmission system according to an embodiment of the present invention;

[0052] Figure 3 A schematic diagram of a system safety and stability limit according to an embodiment of the present invention;

[0053] Figure 4 A schematic diagram of a system safety and stability constraint range according to an embodiment of the present invention;

[0054] Figure 5 A schematic diagram of the delivery capacity of the system according to an embodiment of the present invention;

[0055] Figure 6 A schematic diagram of a photovoltaic thermal power bundling system according to an embodiment of the present invention;

[0056] Figure 7 A schematic diagram of the safety and stability limit of a photovoltaic thermal power bundling system according to an embodiment of the present invention;

[0057] Figure 8 A schematic diagram of a safety and stability constraint range of a photovoltaic thermal power bundling system according to an embodiment of the present invention;

[0058] Fig. 9 A schematic diagram of the delivery capacity of a photovoltaic thermal power bundling system according to an embodiment of the present invention;

[0059] Fig.10 Schematic diagram of the structure of a system 1000 for determining the transmission capacity of a new energy AC transmission system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0060] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0061] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0062] Figure 1FIG. 1 is a flow chart of a method 100 for determining the transmission capacity of a new energy AC transmission system according to an embodiment of the present invention. Figure 1 As shown, the method for determining the delivery capacity of the new energy AC transmission system provided by the embodiment of the present invention can efficiently and accurately determine the delivery capacity of the new energy AC transmission system, and can be applied to large-scale new energy grid-connected systems to ensure the safety and stability of new energy AC transmission. The method 100 for determining the delivery capacity of the new energy AC transmission system provided by the embodiment of the present invention starts from step 101. In step 101, combined with time domain simulation, the total output level of the thermal power unit / the total output level of the new energy unit is maintained unchanged, and the output of the new energy unit / the total output of the thermal power unit is increased to change the operation mode of the system, and the safety and stability limit point of the system after the AC N-1 failure under different operation modes is obtained.

[0063] Preferably, the method further comprises:

[0064] Under different operation modes, the reactive compensation amount in the renewable energy collection station is adjusted to maintain the steady-state renewable energy terminal voltage at 1.00pu before the fault.

[0065] Preferably, the step of obtaining the safety and stability limit point of the system after AC N-1 failure under different operation modes includes:

[0066] Under any operating mode, if the thermal power unit has a power angle instability problem, it is marked as a power angle stability constraint to obtain the power angle stability limit point; if a temporary power frequency overvoltage problem occurs at the new energy machine end, it is marked as an overvoltage safety constraint to obtain the overvoltage safety limit point.

[0067] In the present invention, the new energy AC transmission system is shown as follows Figure 2 As shown in the figure, the renewable energy and thermal power units are bundled and sent out through multiple AC lines. S 、E R are the internal potential amplitudes of equivalent thermal power units at the sending and receiving ends, δ is the power angle of equivalent thermal power units at the sending end, U r · , U c · , U s · They are the voltages of the new energy machine end, the collection station, and the grid connection point, respectively. ss , Z cr , Z ns , Z L The internal potential E S Impedance from the connection point to the grid, impedance from the new energy generator to the collection station, impedance from the collection station to the connection point, impedance from the connection point to the receiving end of the power grid single circuit line, Z c is the equivalent reactance of reactive power compensation in the collection station, I d@ is the active current injected by the new energy. One of the AC channels is selected, and a three-phase permanent short-circuit fault is set at its exit. After 0.10s, the faulty line is removed (hereinafter referred to as AC N-1 fault) to examine the safety and stability limit of the system under the above fault.

[0068] In the invention, time domain simulation is used to find the safety and stability limit point of the system, that is, to maintain a certain total output level of the thermal power unit unchanged, and gradually increase the total output of the new energy unit with a certain step length (valued within a certain interval), thereby forming different corresponding operation modes. It should also be pointed out that in the above different operation modes, the reactive compensation amount in the new energy collection station needs to be appropriately adjusted to maintain the steady-state new energy terminal voltage before the fault at 1.00pu.

[0069] Investigate the safety and stability of the system after the AC N-1 fault under the above different operating modes, that is, the power angle instability of the thermal power unit or the overvoltage problem of the new energy machine end. If a safety and stability problem occurs, it is necessary to record the operating mode corresponding to the previous step, that is, the total output of new energy and thermal power, and mark the power angle stability constraint or overvoltage safety constraint corresponding to the limit point. The specific description is: if the thermal power unit has a power angle instability problem, it is marked as a power angle stability constraint; if a temporary power frequency overvoltage problem occurs at the new energy machine end (the voltage at the machine end of the new energy in the transient process exceeds 1.30pu), it is marked as an overvoltage safety constraint.

[0070] Based on the total output levels of different thermal power units, a series of discrete safety and stability limit points can be obtained according to the above method, such as Figure 3 Similarly, if the total output level of the new energy units is maintained unchanged and the output of the thermal power units is gradually increased at a certain step length, the safety and stability limit that coincides with the above discrete points can be obtained.

[0071] In step 102, a safety and stability boundary is determined based on the safety and stability limit point, and a safety and stability constraint interval is determined based on the marking of the safety and stability limit point and the safety and stability boundary.

[0072] Preferably, the step of determining the safety and stability constraint interval based on the marking conditions of the safety and stability limit points and the safety and stability boundaries comprises:

[0073] Determining a power angle stability constraint interval based on a line connecting at least a preset number of discrete power angle stability limit points;

[0074] Determining an overvoltage safety constraint interval based on a connection line of at least a preset number of discrete overvoltage safety limit points;

[0075] The interval corresponding to the line connecting the discrete safety and stability limit points outside the power angle stability constraint interval and the overvoltage safety constraint interval is taken as the chaos constraint interval.

[0076] In the present invention, the discrete safety and stability limit points obtained in step 101 are connected to obtain the safety and stability boundary, and then the safety and stability constraint interval is identified according to the marking of each limit point. Figure 4 The specific definitions are as follows:

[0077] (1) Power angle stability constraint range

[0078] The line connecting multiple (greater than 3) discrete power angle stability limit points is used as the power angle stability constraint interval, such as Figure 4 When the steady-state operation point before the fault is above the boundary, the thermal power / renewable energy output is increased, and the system power angle instability problem occurs after the AC N-1 fault; when it is below the boundary, the system power angle is stable after the fault and there is no overvoltage problem in the transient process of the renewable energy machine end.

[0079] (2) Overvoltage safety constraint range

[0080] The line connecting multiple (greater than 3) discrete overvoltage safety limit points corresponds to the overvoltage safety constraint interval, such as Figure 4 When the steady-state operation point before the fault is above the boundary, the thermal power / new energy output is increased, and the transient process of the new energy generator after the AC N-1 fault occurs overvoltage; when it is below the boundary, the system power angle is stable after the fault and the transient process of the new energy generator does not occur overvoltage.

[0081] (3) Chaos constraint interval

[0082] In addition to the power angle stability constraint interval and the overvoltage safety constraint interval, the connection line of the discrete safety and stability limit points corresponds to the chaos constraint interval. The safety and stability constraints corresponding to each limit point in this interval are not exactly the same, that is, there are no more than 3 limit points that are continuously subject to the same constraints, such as Figure 4 When the steady-state operation point before the fault is above the boundary, the thermal power / renewable energy output is increased, and after the AC N-1 fault, both the power angle instability problem and the overvoltage problem of the renewable energy generator end may occur; when it is below the boundary, the system power angle is stable after the fault and the transient process of the renewable energy generator end does not have an overvoltage problem.

[0083] In step 103, a linear function curve representing the delivery capacity of the system is determined, the delivery capacity of the system is determined based on the intersection of the linear function curve and the safety and stability boundary, and the type of constraint imposed on the intersection is determined based on the safety and stability constraint interval.

[0084] Preferably, the linear function curve is:

[0085] P 火电 =-P 新能源 +P total ,

[0086] Among them, P 火电 is the total thermal power output; P 新能源 Total output for new energy; P total is the system delivery capacity; the slope of the linear function curve is -1, and the intersection with the y-axis is the intercept, i.e. P total .

[0087] Preferably, the delivery capacity of the system is determined based on the intersection of the linear function curve and the safety and stability boundary, and the type of constraint imposed on the intersection is determined based on the safety and stability constraint interval:

[0088] If the linear function curve has only one intersection with the safety and stability boundary, the unit output corresponding to the intersection is the maximum capacity of the system; at this time, if the intersection is located in the power angle stability constraint interval, the system delivery capacity is subject to the power angle stability constraint; if it is located in the overvoltage safety constraint interval, the system delivery capacity is subject to the overvoltage safety constraint; if it is located in the chaos constraint interval, it may be subject to both the power angle stability constraint and the overvoltage safety constraint;

[0089] If the linear function curve has two intersections with the safety and stability boundary, the delivery capacity range for determining the delivery capacity of the system is [b0, b1], the minimum value of the system delivery capacity is b0, and the maximum value is b1; at this time, any point in the closed area formed by the linear function curve and the safety and stability boundary satisfies the system safety and stability constraints; where b0 is the intercept when the linear function curve has two intersections with the safety and stability boundary; b1 is the intercept when the linear function curve has only one intersection with the safety and stability boundary;

[0090] If the linear function curve does not intersect the safety and stability boundary, there is no steady-state operating point corresponding to the system delivery capacity b2; where b2 is the intercept of the linear function curve.

[0091] The system delivery capacity refers to the power limit that the AC channel can transmit without violating the stability constraints of node voltage over-limit and transient power angle instability. Without considering network losses, the system delivery capacity expression is shown in formula (1):

[0092] P toatl =P 新能源 +P 火电 (1)

[0093] Where P 新能源 Total output of new energy, P 火电 is the total thermal power output, P total Send capacity to the system.

[0094] By transposing the terms in equation (1), we can obtain equation (2):

[0095] P 火电 =-P 新能源 +P total (2)

[0096] At this time, the relationship between the total output of thermal power, the total output of new energy and the system transmission capacity can be regarded as the independent variable P 新能源 , the dependent variable is P 火电 The linear function relationship has a slope of -1, and the intersection with the y-axis is the intercept, that is, P total .

[0097] Therefore, the problem of determining the system delivery capacity will be transformed into the problem of whether there is an intersection between the linear function curve shown in formula (2) and the safety and stability boundary, as follows:

[0098] 1) If there is only one solution, the linear function curve has only one intersection with the safety and stability boundary, and this intersection corresponds to the maximum capacity delivered by the system, such as Figure 5 If the intersection point is located in the power angle stability constraint interval, the system delivery capacity is subject to the power angle stability constraint; if it is located in the overvoltage safety constraint interval, it is subject to the overvoltage safety constraint; if it is located in the chaos constraint interval, it may be subject to both the power angle stability constraint and the overvoltage safety constraint.

[0099] 2) If there are two solutions, the linear function curve intersects with the safe and stable boundary and forms a closed area, such as Figure 5 As shown in the shaded area in the middle. Any point in this area satisfies the system safety and stability constraints, and the system delivery capacity is between the interval [b0, b1], that is, the minimum value of the system delivery capacity is b0 and the maximum value is b1.

[0100] 3) If there is no solution, the linear function curve does not intersect with the safe and stable boundary, that is, a closed area cannot be formed. At this time, there is no steady-state operation point corresponding to the system delivery capacity b2, such as Figure 5 As shown by the upper dotted line.

[0101] The following specifically illustrates the embodiments of the present invention.

[0102] In the present invention, a photovoltaic thermal power bundling system is taken as an example for explanation. Figure 6 As shown in the figure, BusA, BusB, BusC, and BusD are the high-voltage busbars of the thermal power plant, the grid connection point busbar, the high-voltage busbar of the photovoltaic station, and the high-voltage busbar of the receiving system respectively; the line BusA-BusD is the power transmission channel, and Zc is the equivalent impedance of the reactive power compensation of the collection station. Specifically, the process of determining the transmission capacity includes:

[0103] Step 1: Calculation of safety and stability limits

[0104] 1) Use time domain simulation to find the safety and stability limit of the system, maintain the total output level of thermal power units at 1950MW, gradually increase the output of new energy units, and then form different corresponding operation modes. Under the above different operation modes, the reactive compensation amount in the new energy collection station is appropriately adjusted to maintain the steady-state new energy terminal voltage before the fault at 1.00pu.

[0105] The safety and stability of the system after the AC N-1 fault under the above different operating modes are investigated. If the thermal power unit has a power angle instability problem, it is marked as a power angle stability constraint; if a temporary power frequency overvoltage problem occurs at the new energy machine end, it is marked as an overvoltage safety constraint. Based on the total output level of different thermal power units, a series of discrete safety and stability limit points are obtained in the above method, such as Figure 7 shown.

[0106] Step 2: Identification of safety and stability constraint intervals

[0107] Connect the discrete safety and stability limit points obtained in step 1 to obtain the safety and stability boundary, and identify the safety and stability constraint interval according to the marking of each limit point, such as Figure 8 shown.

[0108] 1) The line connecting multiple (greater than 3) discrete power angle stability limit points corresponds to the power angle stability constraint interval, such as Figure 8 As shown in the marked interval on the left.

[0109] 2) The line connecting multiple (greater than 3) discrete overvoltage safety limit points corresponds to the overvoltage safety constraint interval, such as Figure 8 As shown in the marked interval on the right.

[0110] 3) In addition to the power angle stability constraint interval and the overvoltage safety constraint interval, the connection line of the discrete safety and stability limit points corresponds to the chaos constraint interval. The safety and stability constraints corresponding to each limit point in this interval are not exactly the same, that is, there are no more than 3 limit points that are continuously subject to the same constraints, such as Figure 8 As shown in the middle marked interval.

[0111] Step 3: Determine the system delivery capacity

[0112] The problem of determining the system delivery capacity will be transformed into the problem of whether there is an intersection between the linear function curve shown in formula (2) and the safety and stability boundary, such as Fig. 9 shown.

[0113] 1) When the intercept b1 of the linear function curve is 3020, there is only one intersection point between the linear function curve and the system safety and stability boundary, and this intersection point corresponds to the maximum delivery capacity of the system, such as Fig. 9The intersection is located in the chaos constraint interval, indicating that the system transmission capacity corresponding to the intersection is subject to both power angle stability constraints and overvoltage safety constraints.

[0114] 2) When the intercept b0 of the linear function curve is 2900, the linear function curve intersects with the safe and stable boundary, that is, there are two intersection points, and a closed area is formed at this time, such as Fig. 9 As shown in the shaded area in the middle, any point in this area meets the system safety and stability constraints, and the system delivery capacity is between the interval [2900,3020], that is, the minimum value of the system delivery capacity is 2900 and the maximum value is 3020.

[0115] 3) When the intercept b2 of the linear function curve is 3100, the linear function curve does not intersect with the safe and stable boundary, that is, there is no intersection, and a closed area cannot be formed. Fig. 9 As shown by the top dotted line in . At this time, the system does not have a steady-state operating point corresponding to the delivery capacity b2.

[0116] Fig.10 FIG. 1 is a schematic diagram of a system 1000 for determining the transmission capacity of a new energy AC transmission system according to an embodiment of the present invention. Fig.10 As shown, the transmission capacity determination system 1000 of the new energy AC transmission system provided by the embodiment of the present invention includes: a safety and stability limit calculation unit 1001, a safety and stability constraint interval identification unit 1002 and a transmission capacity determination unit 1003.

[0117] Preferably, the safety and stability limit calculation unit 1001 is used to combine time domain simulation to maintain the total output level of the thermal power unit / the total output level of the new energy unit unchanged, increase the output of the new energy unit / the total output of the thermal power unit, so as to change the operation mode of the system, and obtain the safety and stability limit point of the system after the AC N-1 fault under different operation modes.

[0118] Preferably, the system further comprises:

[0119] The adjustment unit is used to adjust the reactive compensation amount in the renewable energy collection station under different operation modes to maintain the steady-state renewable energy terminal voltage at 1.00pu before the fault.

[0120] Preferably, the safety and stability limit calculation unit 1001 obtains the safety and stability limit point of the system after the AC N-1 fault under different operation modes, including:

[0121] Under any operating mode, if the thermal power unit has a power angle instability problem, it is marked as a power angle stability constraint to obtain the power angle stability limit point; if a temporary power frequency overvoltage problem occurs at the new energy machine end, it is marked as an overvoltage safety constraint to obtain the overvoltage safety limit point.

[0122] Preferably, the safety and stability constraint interval identification unit 1002 is used to determine the safety and stability boundary based on the safety and stability limit point, and determine the safety and stability constraint interval based on the marking of the safety and stability limit point and the safety and stability boundary.

[0123] Preferably, the safety and stability constraint interval identification unit 1002 determines the safety and stability constraint interval based on the marking of the safety and stability limit point and the safety and stability boundary, including:

[0124] Determining a power angle stability constraint interval based on a line connecting at least a preset number of discrete power angle stability limit points;

[0125] Determining an overvoltage safety constraint interval based on a connection line of at least a preset number of discrete overvoltage safety limit points;

[0126] The interval corresponding to the line connecting the discrete safety and stability limit points outside the power angle stability constraint interval and the overvoltage safety constraint interval is taken as the chaos constraint interval.

[0127] Preferably, the delivery capacity determination unit 1003 is used to determine a linear function curve representing the delivery capacity of the system, determine the delivery capacity of the system based on the intersection of the linear function curve and the safety and stability boundary, and determine the constraint type of the intersection based on the safety and stability constraint interval.

[0128] Preferably, the linear function curve is:

[0129] P 火电 =-P 新能源 +P total ,

[0130] Among them, P 火电 is the total thermal power output; P 新能源 Total output for new energy; P total is the system delivery capacity; the slope of the linear function curve is -1, and the intersection with the y-axis is the intercept, that is, P total .

[0131] Preferably, the delivery capacity determination unit 1003 determines the delivery capacity of the system based on the intersection of the linear function curve and the safety and stability boundary, and determines the type of constraint of the intersection based on the safety and stability constraint interval:

[0132] If the linear function curve has only one intersection with the safety and stability boundary, the unit output corresponding to the intersection is the maximum capacity of the system; at this time, if the intersection is located in the power angle stability constraint interval, the system delivery capacity is subject to the power angle stability constraint; if it is located in the overvoltage safety constraint interval, the system delivery capacity is subject to the overvoltage safety constraint; if it is located in the chaos constraint interval, it may be subject to both the power angle stability constraint and the overvoltage safety constraint;

[0133] If the linear function curve has two intersections with the safety and stability boundary, the delivery capacity range for determining the delivery capacity of the system is [b0, b1], the minimum value of the system delivery capacity is b0, and the maximum value is b1; at this time, any point in the closed area formed by the linear function curve and the safety and stability boundary satisfies the system safety and stability constraints; where b0 is the intercept when the linear function curve has two intersections with the safety and stability boundary; b1 is the intercept when the linear function curve has only one intersection with the safety and stability boundary;

[0134] If the linear function curve does not intersect the safety and stability boundary, there is no steady-state operating point corresponding to the system delivery capacity b2; where b2 is the intercept of the linear function curve.

[0135] The transmission capacity determination system 1000 of the new energy AC transmission system of the embodiment of the present invention corresponds to the transmission capacity determination method 100 of the new energy AC transmission system of another embodiment of the present invention, which will not be described in detail here.

[0136] Based on another aspect of the present invention, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any step of a method for determining a transmission capacity of a new energy AC transmission system.

[0137] According to another aspect of the present invention, the present invention provides an electronic device, including:

[0138] The computer-readable storage medium described above; and

[0139] One or more processors are used to execute the program in the computer-readable storage medium.

[0140] The invention has been described above with reference to a few embodiments. However, it is readily apparent to a person skilled in the art that other embodiments than the ones disclosed above are equally within the scope of the invention, as defined by the appended patent claims.

[0141] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise therein. All references to "a / said / the [means, components, etc.]" are to be openly interpreted as at least one instance of said means, components, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not necessarily have to be performed in the exact order disclosed, unless explicitly stated otherwise.

[0142] 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.

[0143] 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.

[0144] 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 1 A function specified in one or more boxes.

[0145] 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. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0146] 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 it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for determining the delivery capacity of a new energy AC delivery system, characterized in that: The method comprises: Combined with time domain simulation, the total output of thermal power units / new energy units is maintained unchanged, and the output of new energy units / thermal power units is increased to change the operation mode of the system, and the safety and stability limit points of the system after AC N-1 fault under different operation modes are obtained; Determining a safe and stable boundary based on the safe and stable limit point, and determining a safe and stable constraint interval based on the marking of the safe and stable limit point and the safe and stable boundary; A linear function curve representing the delivery capacity of the system is determined, the delivery capacity of the system is determined based on the intersection of the linear function curve and the safety and stability boundary, and the type of constraint imposed on the intersection is determined based on the safety and stability constraint interval.

2. The method according to claim 1, characterized in that The method further comprises: Under different operation modes, the reactive compensation amount in the renewable energy collection station is adjusted to maintain the steady-state renewable energy terminal voltage at 1.00pu before the fault.

3. The method according to claim 1, characterized in that The step of obtaining the safety and stability limit point of the system after AC N-1 failure under different operation modes includes: Under any operating mode, if the thermal power unit has a power angle instability problem, it is marked as a power angle stability constraint to obtain the power angle stability limit point; if a temporary power frequency overvoltage problem occurs at the new energy machine end, it is marked as an overvoltage safety constraint to obtain the overvoltage safety limit point.

4. The method according to claim 1, characterized in that: The step of determining the safety and stability constraint interval based on the marking of the safety and stability limit point and the safety and stability boundary includes: Determining a power angle stability constraint interval based on a line connecting at least a preset number of discrete power angle stability limit points; Determining an overvoltage safety constraint interval based on a connection line of at least a preset number of discrete overvoltage safety limit points; The interval corresponding to the line connecting the discrete safety and stability limit points outside the power angle stability constraint interval and the overvoltage safety constraint interval is taken as the chaos constraint interval.

5. The method according to claim 1, characterized in that The linear function curve is: P 火电 =-P 新能源 +P total , Among them, P 火电 is the total thermal power output; P 新能源 Total output for new energy; P total is the system delivery capacity; the slope of the linear function curve is -1, and the intersection with the y-axis is the intercept, i.e. P total .

6. The method according to claim 1, characterized in that The delivery capacity of the system is determined based on the intersection of the linear function curve and the safety and stability boundary, and the type of constraint imposed on the intersection is determined based on the safety and stability constraint interval: If the linear function curve has only one intersection with the safety and stability boundary, the unit output corresponding to the intersection is the maximum capacity of the system; at this time, if the intersection is located in the power angle stability constraint interval, the system delivery capacity is subject to the power angle stability constraint; if it is located in the overvoltage safety constraint interval, the system delivery capacity is subject to the overvoltage safety constraint; if it is located in the chaos constraint interval, it may be subject to both the power angle stability constraint and the overvoltage safety constraint; If the linear function curve has two intersections with the safety and stability boundary, the delivery capacity range for determining the delivery capacity of the system is [b0, b1], the minimum value of the system delivery capacity is b0, and the maximum value is b1; at this time, any point in the closed area formed by the linear function curve and the safety and stability boundary satisfies the system safety and stability constraints; where b0 is the intercept when the linear function curve has two intersections with the safety and stability boundary; b1 is the intercept when the linear function curve has only one intersection with the safety and stability boundary; If the linear function curve does not intersect the safety and stability boundary, there is no steady-state operating point corresponding to the system delivery capacity b2; where b2 is the intercept of the linear function curve.

7. A system for determining the delivery capacity of a new energy AC delivery system, characterized in that: The system comprises: The safety and stability limit calculation unit is used to combine time domain simulation to maintain the total output of thermal power units / new energy units unchanged, increase the output of new energy units / total output of thermal power units, so as to change the operation mode of the system and obtain the safety and stability limit points of the system after AC N-1 fault under different operation modes; A safety and stability constraint interval identification unit, used to determine a safety and stability boundary based on the safety and stability limit point, and determine a safety and stability constraint interval based on the marking of the safety and stability limit point and the safety and stability boundary; The delivery capacity determination unit is used to determine a linear function curve representing the delivery capacity of the system, determine the delivery capacity of the system based on the intersection of the linear function curve and the safety and stability boundary, and determine the constraint type of the intersection based on the safety and stability constraint interval.

8. The system according to claim 7, characterized in that The system further comprises: The adjustment unit is used to adjust the reactive compensation amount in the renewable energy collection station under different operation modes to maintain the steady-state renewable energy terminal voltage at 1.00pu before the fault.

9. The system according to claim 7, characterized in that The safety and stability limit calculation unit obtains the safety and stability limit point of the system after AC N-1 failure under different operation modes, including: Under any operating mode, if the thermal power unit has a power angle instability problem, it is marked as a power angle stability constraint to obtain the power angle stability limit point; if a temporary power frequency overvoltage problem occurs at the new energy machine end, it is marked as an overvoltage safety constraint to obtain the overvoltage safety limit point.

10. The system according to claim 7, characterized in that The safety and stability constraint interval identification unit determines the safety and stability constraint interval based on the marking of the safety and stability limit point and the safety and stability boundary, including: Determining a power angle stability constraint interval based on a line connecting at least a preset number of discrete power angle stability limit points; Determining an overvoltage safety constraint interval based on a connection line of at least a preset number of discrete overvoltage safety limit points; The interval corresponding to the line connecting the discrete safety and stability limit points outside the power angle stability constraint interval and the overvoltage safety constraint interval is taken as the chaos constraint interval.

11. The system according to claim 7, characterized in that The linear function curve is: P 火电 =-P 新能源 +P total , Among them, P 火电 is the total thermal power output; P 新能源 Total output for new energy; P total is the system delivery capacity; the slope of the linear function curve is -1, and the intersection with the y-axis is the intercept, i.e. P total .

12. The system according to claim 7, characterized in that The delivery capacity determination unit determines the delivery capacity of the system based on the intersection of the linear function curve and the safety and stability boundary, and determines the type of constraint of the intersection based on the safety and stability constraint interval: If the linear function curve has only one intersection with the safety and stability boundary, the unit output corresponding to the intersection is the maximum capacity of the system; at this time, if the intersection is located in the power angle stability constraint interval, the system delivery capacity is subject to the power angle stability constraint; if it is located in the overvoltage safety constraint interval, the system delivery capacity is subject to the overvoltage safety constraint; if it is located in the chaos constraint interval, it may be subject to both the power angle stability constraint and the overvoltage safety constraint; If the linear function curve has two intersections with the safety and stability boundary, the delivery capacity range for determining the delivery capacity of the system is [b0, b1], the minimum value of the system delivery capacity is b0, and the maximum value is b1; at this time, any point in the closed area formed by the linear function curve and the safety and stability boundary satisfies the system safety and stability constraints; where b0 is the intercept when the linear function curve has two intersections with the safety and stability boundary; b1 is the intercept when the linear function curve has only one intersection with the safety and stability boundary; If the linear function curve does not intersect the safety and stability boundary, there is no steady-state operating point corresponding to the system delivery capacity b2; where b2 is the intercept of the linear function curve.

13. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

14. An electronic device, characterized in that: include: The computer readable storage medium as claimed in claim 13; as well as One or more processors are used to execute the program in the computer-readable storage medium.

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