Electric power system new energy multi-station critical transmission power calculation method and system and storage medium

Abstract

The invention discloses a new energy multi-station critical transmission power calculation method for a power system. The method comprises the following steps: acquiring data information of a target power system; calculating a new energy multi-station short-circuit ratio and a critical short-circuit ratio of a grid-connected node to which the target new energy station belongs; and according to the obtained new energy multi-station short-circuit ratio and the critical short-circuit ratio, calculating to obtain the new energy multi-station critical transmission power of the power system. The invention also discloses a system for realizing the method for calculating the critical transmission power of the new energy multi-station of the electric power system, and a storage medium comprising the method for calculating the critical transmission power of the new energy multi-station of the electric power system. According to the method, the calculation of the new energy multi-station critical transmission power of the electric power system is realized, the reliability is higher, and the accuracy is better.

Description

Technical Field

[0001] This invention belongs to the field of electrical automation, and specifically relates to a method, system and storage medium for calculating the critical transmission power of multiple new energy power stations in a power system. Background Technology

[0002] With economic and technological development and the improvement of people's living standards, electricity has become an indispensable secondary energy source in people's production and daily life, bringing endless convenience. Therefore, ensuring a stable and reliable supply of electricity has become one of the most important tasks of the power system.

[0003] At present, as the penetration rate of new energy power generation such as wind power and photovoltaic power generation in the power system continues to increase, the inherent volatility and intermittency of new energy power generation and the low inertia and weak support characteristics of grid-connected power electronic equipment pose a severe challenge to the stable operation of the power system.

[0004] In traditional power systems, the power angle stability analysis theory based on synchronous generators is quite mature. However, for multi-station renewable energy systems dominated by power electronic equipment, multiple stations interact with each other through the power grid, and their voltage source phase dynamics exhibit a significant "power angle coupling" effect. Therefore, power angle stability will constrain the power transmission limit of renewable energy stations. However, current derivations of the output power limit of renewable energy stations are mostly based on individual stations and voltage stability constraints, without considering the coupling effect between multiple stations and the power angle stability constraints. Therefore, existing calculations of the output power limit of renewable energy stations often suffer from poor reliability and accuracy. Summary of the Invention

[0005] One of the objectives of this invention is to provide a highly reliable and accurate method for calculating the critical transmission power of multiple power stations for new energy sources in a power system.

[0006] The second objective of this invention is to provide a system for calculating the critical transmission power of multiple power stations for new energy sources in the power system.

[0007] A third objective of this invention is to provide a storage medium on which a computer program is stored; when the computer program is executed by a processor, it implements the method for calculating the critical transmission power of multiple power stations for new energy sources in the power system.

[0008] The method for calculating the critical transmission power of multiple renewable energy power plants in a power system provided by this invention includes the following steps:

[0009] S1. Obtain data information about the target power system;

[0010] S2. Based on the data obtained in step S1, calculate the short-circuit ratio and critical short-circuit ratio of the new energy power stations at the grid-connected node to which the target new energy power station belongs;

[0011] S3. Based on the short-circuit ratio and critical short-circuit ratio of the new energy multi-station obtained in step S2, calculate the critical transmission power of the new energy multi-station in the power system.

[0012] Step S1, which involves acquiring data information about the target power system, specifically includes the following steps:

[0013] Acquire data information from the target power system;

[0014] The data information includes the active power of the grid-connected node to which the target renewable energy power station belongs. reactive power Apparent power Branch impedance of the line Line impedance angle Self-impedance mutual impedance Voltage phasors and short-circuit capacity ;in The branch resistance of the line where the grid connection node of the target new energy power station is located. The branch reactance of the line where the grid connection node of the target new energy power station is located; among which, mutual impedance The mutual impedance is defined as the mutual impedance between the grid-connected node of the target renewable energy power station and the grid-connected node of the j-th renewable energy power station (excluding the target renewable energy power station).

[0015] The data information includes the active power output of the j-th renewable energy power station other than the target renewable energy power station. reactive power Apparent power Voltage phasors of the grid-connected nodes and the branch impedance of the line ;in Let be the branch resistance of the line where the grid-connected node of the j-th renewable energy power station (excluding the target renewable energy power station) is located. The branch reactance is the line of the grid-connected node of the j-th new energy power station (excluding the target new energy power station);

[0016] The data information includes the node voltage amplitude at the convergence point of multiple new energy power stations. Grid-side impedance Grid-side voltage amplitude and grid-side impedance angle ;in, For grid-side resistance, This refers to the grid-side reactance.

[0017] Step S2, calculating the short-circuit ratio of multiple renewable energy power stations, specifically includes the following steps:

[0018] The short-circuit ratio of multiple new energy power stations is calculated using the following formula. :

[0019] In the formula, n represents the total number of new energy power stations other than the target new energy power station; A represents the target new energy power station; The voltage at the grid connection point of the target renewable energy power station; for Conjugate; for Conjugate; This refers to the voltage at the grid connection point of other new energy power stations besides the target new energy power station.

[0020] The calculation of the critical short-circuit ratio in step S2 specifically includes the following steps:

[0021] The active power passing through the line between the new energy multi-site collection point and the AC power grid is calculated using the following formula. :

[0022] In the formula The ratio of the resistance value between the grid connection point and the aggregation point of the new energy multi-site to the square of its corresponding impedance value is expressed as: , The impedance between the grid connection point and the new energy multi-site aggregation point and ; The voltage at the convergence point of multiple new energy power stations; The phase angle difference between the voltage phasors at the convergence point of multiple new energy power plants and the voltage phasors of the AC power grid. The ratio of the reactance value to the square of the corresponding impedance value between the grid connection point and the new energy multi-station aggregation point is expressed as: ;

[0023] Will Find the expression about The partial derivatives are obtained. ;

[0024] make The active power limit of the line between the new energy multi-site collection point and the AC power grid is obtained. and the corresponding phase angle difference limit value , represented as

[0025] Active power limit of the line between the new energy multi-site convergence point and the AC power grid Under the constraints, the active power limit of the target new energy power station Represented as ,in It is the sum of the active power output of all new energy power stations except the target new energy power station;

[0026] The active power of the line between the grid connection node of the target renewable energy power station and the convergence point of multiple renewable energy power stations is calculated using the following formula. :

[0027] In the formula The ratio of the resistance value between the new energy multi-site collection point and the target new energy site to the square of the corresponding impedance value is expressed as: , The impedance between the new energy multi-site aggregation point and the target new energy site and ; The phase angle difference between the voltage phasor of the grid-connected node to which the target renewable energy power station belongs and the voltage phasor of the convergence point of multiple renewable energy power stations; The ratio of the square of the reactance value to the square of the corresponding impedance value between the new energy multi-site aggregation point and the target new energy site is expressed as: ;

[0028] Will Find the expression about The partial derivatives are obtained. ;

[0029] make The active power limit of the line between the grid connection node of the target renewable energy power station and the convergence point of multiple renewable energy power stations is obtained. and the corresponding phase angle difference limit value , represented as

[0030] Finally, the critical short-circuit ratio of the grid-connected node to which the target renewable energy power station belongs is calculated using the following formula, without considering the coupling of multiple power stations. :

[0031] In the formula To disregard the maximum output power of the target renewable energy power station when multiple power stations are coupled, and .

[0032] Step S3, which involves calculating the critical transmission power of the power system's new energy multi-station based on the short-circuit ratio and critical short-circuit ratio obtained in step S2, specifically includes the following steps:

[0033] when and When they are equal, the critical transmission power of multiple power stations for new energy sources in the power system is obtained;

[0034] make The following equation is obtained:

[0035] And thus obtain ;

[0036] For the formula The critical transmission power of the target renewable energy power station is obtained by solving the problem. , represented as

[0037] In the formula For the intermediate substitution variable set, and .

[0038] This invention also provides a system for implementing the method for calculating the critical transmission power of multiple renewable energy power plants in a power system, comprising a data acquisition module, a short-circuit ratio calculation module, and a criticality calculation module; the data acquisition module, short-circuit ratio calculation module, and criticality calculation module are connected in series; the data acquisition module is used to acquire data information of the target power system and upload the data information to the short-circuit ratio calculation module; the short-circuit ratio calculation module is used to calculate the short-circuit ratio and critical short-circuit ratio of the renewable energy power plant to which the grid-connected node belongs, based on the received data information and the acquired data information, and upload the data information to the criticality calculation module; the criticality calculation module is used to calculate the critical transmission power of the multiple renewable energy power plants in the power system based on the received data information and the obtained short-circuit ratio and critical short-circuit ratio of the renewable energy power plants.

[0039] The present invention also provides a storage medium on which a computer program is stored; when the computer program is executed by a processor, it implements the method for calculating the critical transmission power of multiple power stations for new energy in the power system.

[0040] The present invention provides a method, system, and storage medium for calculating the critical transmission power of multiple new energy power stations in a power system. By calculating the short-circuit ratio and critical short-circuit ratio of multiple new energy power stations, and by analyzing the calculated short-circuit ratio and critical short-circuit ratio of the new energy power stations, it not only realizes the calculation of the critical transmission power of multiple new energy power stations in a power system, but also has higher reliability and better accuracy. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the method flow of the present invention.

[0042] Figure 2 This is a schematic diagram of the structure of a multi-wind farm grid-connected system according to an embodiment of the method of the present invention.

[0043] Figure 3 This is a schematic diagram of the simulation curve results of an embodiment of the method of the present invention.

[0044] Figure 4 This is a schematic diagram of the functional modules of the system of the present invention. Detailed Implementation

[0045] like Figure 1 The diagram shown is a flowchart of the method of the present invention: The critical transmission power calculation method for multiple power stations of new energy sources in the power system disclosed in this invention includes the following steps:

[0046] S1. Obtain data information of the target power system; specifically including the following steps:

[0047] Acquire data information from the target power system;

[0048] The data information includes the active power of the grid-connected node to which the target renewable energy power station (i.e., the renewable energy power station to be evaluated) belongs. reactive power Apparent power Branch impedance of the line Line impedance angle Self-impedance mutual impedance Voltage phasors and short-circuit capacity ;in The branch resistance of the line where the grid connection node of the target new energy power station is located. The branch reactance of the line where the grid connection node of the target new energy power station is located; among which, mutual impedance The mutual impedance is defined as the mutual impedance between the grid-connected node of the target renewable energy power station and the grid-connected node of the j-th renewable energy power station (excluding the target renewable energy power station).

[0049] The data information includes the active power output of the j-th renewable energy power station other than the target renewable energy power station. reactive power Apparent power Voltage phasors of the grid-connected nodes and the branch impedance of the line ;in Let be the branch resistance of the line where the grid-connected node of the j-th renewable energy power station (excluding the target renewable energy power station) is located. The branch reactance is the line of the grid-connected node of the j-th new energy power station (excluding the target new energy power station);

[0050] The data information includes the node voltage amplitude at the convergence point of multiple new energy power stations. Grid-side impedance Grid-side voltage amplitude and grid-side impedance angle ;in, For grid-side resistance, For grid-side reactance;

[0051] S2. Based on the data obtained in step S1, calculate the short-circuit ratio and critical short-circuit ratio of the new energy power stations at the grid-connected node to which the target new energy power station belongs;

[0052] In practice, calculating the short-circuit ratio of multiple new energy power stations involves the following steps:

[0053] The short-circuit ratio of multiple new energy power stations is calculated using the following formula. :

[0054] In the formula, n represents the total number of new energy power stations other than the target new energy power station; A represents the target new energy power station; The voltage at the grid connection point of the target renewable energy power station; for Conjugate; for Conjugate; The voltage at the grid connection point of other new energy power stations besides the target new energy power station;

[0055] In practice, calculating the critical short-circuit ratio involves the following steps:

[0056] The active power passing through the line between the new energy multi-site collection point and the AC power grid is calculated using the following formula. :

[0057] In the formula The ratio of the resistance value between the grid connection point and the aggregation point of the new energy multi-site to the square of its corresponding impedance value is expressed as: , The impedance between the grid connection point and the new energy multi-site aggregation point and ; The voltage at the convergence point of multiple new energy power stations; The phase angle difference between the voltage phasors at the convergence point of multiple new energy power plants and the voltage phasors of the AC power grid. The ratio of the reactance value to the square of the corresponding impedance value between the grid connection point and the new energy multi-station aggregation point is expressed as: ;

[0058] Will Given the expression, find the expression about The partial derivatives are obtained. ;

[0059] make The active power limit of the line between the new energy multi-site collection point and the AC power grid is obtained. and the corresponding phase angle difference limit value , represented as

[0060] Active power limit of the line between the new energy multi-site convergence point and the AC power grid Under the constraints, the active power limit of the target new energy power station Represented as ,in It is the sum of the active power output of all new energy power stations except the target new energy power station;

[0061] The active power of the line between the grid connection node of the target renewable energy power station and the convergence point of multiple renewable energy power stations is calculated using the following formula. :

[0062] In the formula The ratio of the resistance value between the new energy multi-site collection point and the target new energy site to the square of the corresponding impedance value is expressed as: , The impedance between the new energy multi-site aggregation point and the target new energy site and ; The phase angle difference between the voltage phasor of the grid-connected node to which the target renewable energy power station belongs and the voltage phasor of the convergence point of multiple renewable energy power stations; The ratio of the square of the reactance value to the square of the corresponding impedance value between the new energy multi-site aggregation point and the target new energy site is expressed as: ;

[0063] Will Given the expression, find the expression about The partial derivatives are obtained. ;

[0064] make The active power limit of the line between the grid connection node of the target renewable energy power station and the convergence point of multiple renewable energy power stations is obtained. and the corresponding phase angle difference limit value , represented as

[0065] Finally, the critical short-circuit ratio of the grid-connected node to which the target renewable energy power station belongs is calculated using the following formula, without considering the coupling of multiple power stations. :

[0066] In the formula To disregard the maximum output power of the target renewable energy power station when multiple power stations are coupled, and ;

[0067] S3. Based on the short-circuit ratio and critical short-circuit ratio of the new energy power plants obtained in step S2, calculate the critical transmission power of the new energy power plants in the power system; specifically including the following steps:

[0068] When the grid connection node of the target new energy power station meets the requirements At that time, the station meets the conditions for stable power angle and can operate stably without considering other factors that affect stability;

[0069] when and When they are equal, the critical transmission power of multiple power stations for new energy sources in the power system is obtained;

[0070] make The following equation is obtained:

[0071] And thus obtain ;

[0072] For the formula The critical transmission power of the target renewable energy power station is obtained by solving the problem. , represented as

[0073] In the formula For the intermediate substitution variable set, and .

[0074] The feasibility of the method of the present invention will be illustrated below with reference to an embodiment:

[0075] The Digsilent / PowerFactory simulation platform was used to simulate the target control system (topology as follows) Figure 2 Modeling and simulation analysis were performed on the model (shown in Table 1). The simulation model includes two wind farms, A and B, connected in parallel to a common busbar, transmission lines, and the power grid. The simulation parameters are shown in Table 1.

[0076] During the simulation, the active power output of station A is increased, and a three-phase short-circuit fault is applied to node A at 1s, and the fault is cleared at 1.1s, until station A loses stability.

[0077] The curves obtained during the simulation are as follows Figure 3 As shown: Among them, Figure 3 (a) is a schematic diagram of the curve during normal operation. ; Figure 3 (b) is a schematic diagram of the curve during normal operation. ; Figure 3 (c) is a schematic diagram of the curve at the critical steady state, at which point... ; Figure 4 (c) is a schematic diagram of the curve when the system loses stability and subsequent simulations are impossible. .

[0078] Simulation curves and calculations show that the obtained critical output power has an error of only 5% compared with the critical output power derived by the method of this invention (simulation value is 0.4 pu, calculated value is 0.42 pu); this indicates that the method of this invention has high reliability and accuracy.

[0079] like Figure 4 The diagram shows the functional modules of the system of the present invention: The system disclosed in this invention for calculating the critical transmission power of multiple renewable energy power plants in a power system includes a data acquisition module, a short-circuit ratio calculation module, and a criticality calculation module; the data acquisition module, the short-circuit ratio calculation module, and the criticality calculation module are connected in series; the data acquisition module is used to acquire data information of the target power system and upload the data information to the short-circuit ratio calculation module; the short-circuit ratio calculation module is used to calculate the short-circuit ratio and critical short-circuit ratio of the renewable energy power plant to which the grid-connected node belongs, based on the received data information and the acquired data information, and upload the data information to the criticality calculation module; the criticality calculation module is used to calculate the critical transmission power of the renewable energy power plant in the power system based on the received data information and the obtained short-circuit ratio and critical short-circuit ratio of the renewable energy power plant.

Claims

1. A method for calculating the critical transmission power of multiple renewable energy power plants in a power system, comprising the following steps: S1. Obtain data information about the target power system; S2. Based on the data obtained in step S1, calculate the short-circuit ratio and critical short-circuit ratio of the new energy power stations at the grid-connected node to which the target new energy power station belongs; S3. Based on the short-circuit ratio and critical short-circuit ratio of the new energy multi-station obtained in step S2, calculate the critical transmission power of the new energy multi-station in the power system.

2. The method for calculating the critical transmission power of multiple power stations for new energy sources in a power system according to claim 1, characterized in that... Step S1, which involves acquiring data information about the target power system, specifically includes the following steps: Acquire data information from the target power system; The data information includes the active power of the grid-connected node to which the target renewable energy power station belongs. reactive power Apparent power Branch impedance of the line Line impedance angle Self-impedance mutual impedance Voltage phasors and short-circuit capacity ;in The branch resistance of the line where the grid connection node of the target new energy power station is located. The branch reactance of the line where the grid connection node of the target new energy power station is located; among which, mutual impedance The mutual impedance is defined as the mutual impedance between the grid-connected node of the target renewable energy power station and the grid-connected node of the j-th renewable energy power station (excluding the target renewable energy power station). The data information includes the active power output of the j-th renewable energy power station other than the target renewable energy power station. reactive power Apparent power Voltage phasors of the grid-connected nodes and the branch impedance of the line ;in Let be the branch resistance of the line where the grid-connected node of the j-th renewable energy power station (excluding the target renewable energy power station) is located. The branch reactance is the line of the grid-connected node of the j-th new energy power station (excluding the target new energy power station); The data information includes the node voltage amplitude at the convergence point of multiple new energy power stations. Grid-side impedance Grid-side voltage amplitude and grid-side impedance angle ;in, For grid-side resistance, This refers to the grid-side reactance.

3. The method for calculating the critical transmission power of multiple power stations for new energy sources in a power system according to claim 2, characterized in that... Step S2, calculating the short-circuit ratio of multiple renewable energy power stations, specifically includes the following steps: The short-circuit ratio of multiple new energy power stations is calculated using the following formula. : In the formula, n represents the total number of new energy power stations other than the target new energy power station; A represents the target new energy power station; The voltage at the grid connection point of the target renewable energy power station; for Conjugate; for Conjugate; This refers to the voltage at the grid connection point of other new energy power stations besides the target new energy power station.

4. The method for calculating the critical transmission power of multiple power stations for new energy sources in a power system according to claim 3, characterized in that... The calculation of the critical short-circuit ratio in step S2 specifically includes the following steps: The active power passing through the line between the new energy multi-site collection point and the AC power grid is calculated using the following formula. : In the formula The ratio of the resistance value between the grid connection point and the aggregation point of the new energy multi-site to the square of its corresponding impedance value is expressed as: , The impedance between the grid connection point and the new energy multi-site aggregation point and ; The voltage at the convergence point of multiple new energy power stations; The phase angle difference between the voltage phasors at the convergence point of multiple new energy power plants and the voltage phasors of the AC power grid. The ratio of the reactance value to the square of the corresponding impedance value between the grid connection point and the new energy multi-station aggregation point is expressed as: ; Will Given the expression, find the expression about The partial derivatives are obtained. ; make The active power limit of the line between the new energy multi-site collection point and the AC power grid is obtained. and the corresponding phase angle difference limit value , represented as Active power limit of the line between the new energy multi-site convergence point and the AC power grid Under the constraints, the active power limit of the target new energy power station Represented as ,in It is the sum of the active power output of all new energy power stations except the target new energy power station; The active power of the line between the grid connection node of the target renewable energy power station and the convergence point of multiple renewable energy power stations is calculated using the following formula. : In the formula The ratio of the resistance value between the new energy multi-site collection point and the target new energy site to the square of the corresponding impedance value is expressed as: , The impedance between the new energy multi-site aggregation point and the target new energy site and ; The phase angle difference between the voltage phasor of the grid-connected node to which the target renewable energy power station belongs and the voltage phasor of the convergence point of multiple renewable energy power stations; The ratio of the square of the reactance value to the square of the corresponding impedance value between the new energy multi-site aggregation point and the target new energy site is expressed as: ; Will Given the expression, find the expression about The partial derivatives are obtained. ; make The active power limit of the line between the grid connection node of the target renewable energy power station and the convergence point of multiple renewable energy power stations is obtained. and the corresponding phase angle difference limit value , represented as Finally, the critical short-circuit ratio of the grid-connected node to which the target renewable energy power station belongs is calculated using the following formula, without considering the coupling of multiple power stations. : In the formula To disregard the maximum output power of the target renewable energy power station when multiple power stations are coupled, and .

5. The method for calculating the critical transmission power of multiple power stations for new energy sources in a power system according to claim 4, characterized in that... Step S3, which involves calculating the critical transmission power of the power system's new energy multi-station based on the short-circuit ratio and critical short-circuit ratio obtained in step S2, specifically includes the following steps: when and When they are equal, the critical transmission power of multiple power stations for new energy sources in the power system is obtained; make The following equation is obtained: And thus obtain ; For the formula The critical transmission power of the target renewable energy power station is obtained by solving the problem. , represented as In the formula For the intermediate substitution variable set, and .

6. A system for implementing the critical transmission power calculation method for multiple power stations of new energy sources in a power system as described in any one of claims 1 to 5, characterized in that... It includes a data acquisition module, a short-circuit ratio calculation module, and a criticality calculation module; the data acquisition module, the short-circuit ratio calculation module, and the criticality calculation module are connected in series; the data acquisition module is used to acquire data information of the target power system and upload the data information to the short-circuit ratio calculation module; the short-circuit ratio calculation module is used to calculate the short-circuit ratio and critical short-circuit ratio of the new energy power station to which the grid-connected node belongs, based on the received data information and the acquired data information, and upload the data information to the criticality calculation module; The critical calculation module is used to calculate the critical transmission power of the power system's new energy multi-stations based on the received data information, the obtained short-circuit ratio of the new energy multi-stations, and the critical short-circuit ratio.

7. A storage medium storing a computer program thereon; when the computer program is executed by a processor, it implements the critical transmission power calculation method for multiple power stations of new energy in a power system as described in any one of claims 1 to 5.

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