CN-121980722-A - Fault simulation calculation method and system for network-structured fan access system

CN121980722ACN 121980722 ACN121980722 ACN 121980722ACN-121980722-A

Abstract

The invention discloses a fault simulation calculation method and a fault simulation calculation system of a grid-formed fan access system, which relate to the field of power system fault simulation modeling, wherein the grid-formed fan comprises a wind turbine generator body and a grid-formed inverter power supply, active and reactive power simulation calculation models are built based on a grid-formed inverter power supply control strategy, and then an equivalent model of the grid-formed inverter power supply during faults is built; based on the fault equivalent model, a composite sequence net equivalent model under the fault condition of the power distribution network with the grid-structured inverter power supply is established according to the network structure of the power distribution network, a loop equation set formed by a generalized matrix is obtained based on the composite sequence net equivalent model, the loop equation set and the grid-structured power supply fault equivalent model are combined, and the fault quantity is solved by adopting an iterative calculation method according to the constraints of the output power and the current characteristics and the power and voltage relation of the grid-structured power supply. The method solves the problem that the traditional fault analysis and calculation method based on the synchronous machine power supply cannot adapt to the access scene of the network-structured fan.

Inventors

PENG FANG
GAO HOULEI
DING LEI
SONG HAORAN
Yan Jiongcheng

Assignees

山东大学

Dates

Publication Date: 20260505
Application Date: 20260407

Claims (10)

1. The fault simulation calculation method of the network-structured fan access system is characterized in that the network-structured fan comprises a wind turbine body and a network-structured inverter power supply, and comprises the following steps: based on a network-structured inverter control strategy of virtual synchronous machines, analyzing the characteristics of output power of the network-structured inverter in a steady state of power distribution network faults, and establishing an active and reactive power simulation calculation model of the network-structured inverter in the fault state; based on the network-structured inverter power supply fault equivalent model, establishing a composite sequence network equivalent model under the fault condition of the power distribution network containing the network-structured inverter power supply according to the network structure of the power distribution network; Based on the composite sequence net equivalent model, obtaining a loop equation set formed by a generalized matrix according to a circuit theorem; and the loop equation set and the network inverter power supply fault equivalent model are combined, and an iterative calculation method is adopted to solve the fault quantity according to the constraints of the output power, the current characteristics and the power-voltage relation of the network inverter power supply.
2. The method for simulating and calculating the fault of a network fan access system according to claim 1, wherein the network inverter adopts positive and negative sequence separation control, and the negative sequence loop adopts a control mode for inhibiting negative sequence current.
3. The method for simulating and calculating the fault of a network-structured fan access system according to claim 1, wherein the reactive power of the network-structured inverter power supply satisfies the following formula when the power distribution network is in a fault steady state: Wherein, the For the reactive power to be supplied, As a reference value for the reactive power, To reflect the voltage adjustment coefficient of the reactive-voltage sag characteristic, As a reference value for the system voltage, The voltage between the transformer and the filter inductance is boosted for the grid-formed inverter.
4. The method for calculating the fault simulation of the network-structured fan access system according to claim 1, wherein the association relationship between the output positive sequence current and the power of the network-structured inverter power supply is as follows: the output negative sequence current is: Wherein, the Is a positive sequence current, and the current is a positive sequence current, In the case of a negative sequence current, The visual power is transmitted to the grid-connected point for the grid-structured inverter power supply, Voltage phasors between the boost transformer and the filter inductor of the grid-formed inverter power supply; Is a conjugate phasor.
5. The method for simulating and calculating the fault of the network-structured fan access system according to claim 1, wherein the composite sequence network equivalent model under the fault condition of the power distribution network with the network-structured inverter is composed of a positive sequence network with the network-structured inverter and a negative sequence network without the power supply.
6. The method for simulating and calculating the fault of a network fan access system according to claim 1, wherein the loop equation set formed by the generalized matrix is as follows: Wherein, the Is that Is used to correct the loop impedance matrix of the circuit, In order to achieve the number of circuit circuits in the circuit, Is that Is A is the loop current vector of Is associated with the DG branch, Is that Is used for the voltage vector of the power distribution network voltage source, Is that The grid-structured inverter power supply outputs a current vector.
7. The method for simulating and calculating the fault of a network fan access system according to claim 1, wherein the constraint of the power-voltage relationship is expressed as: Wherein, the In order for the active power to be available, To build up the reactance of the step-up transformer of the grid-type inverter, To boost the voltage between the transformer and the filter inductance for a grid-formed inverter, Is the positive sequence voltage of the grid-connected point, Is the phasor And (3) with The difference in phase of (2); The convergence criterion of the iterative calculation method is as follows: Wherein, the As a function of the maximum value, For the ith network-structured DG The difference between the current amplitude and the last iteration amplitude, Is the first Individual net type DG The difference between the current amplitude and the last iteration amplitude, Is the threshold of the convergence criterion.
8. The utility model provides a network formation type fan inserts trouble simulation computing system of system which characterized in that, network formation type fan includes wind turbine generator system body and network formation type inverter power supply, and the system includes: The system comprises a fault equivalent model construction module, a network-structured inverter power supply fault equivalent model generation module and a power distribution network fault simulation module, wherein the fault equivalent model construction module is configured to analyze the characteristics of output power of the network-structured inverter power supply when a power distribution network is in a fault steady state based on a network-structured inverter power supply control strategy of a virtual synchronous machine type, and establish an active and reactive power simulation calculation model when the network-structured inverter power supply is in a fault state; The fault equivalent circuit construction module is configured to establish a composite sequence net equivalent model under the fault condition of the power distribution network containing the grid-structured inverter power supply according to the network structure of the power distribution network based on the grid-structured inverter power supply fault equivalent model; The generalized matrix form equation set construction module is configured to obtain a loop equation set formed by a generalized matrix according to a circuit theorem based on the composite sequence net equivalent model; The fault electric quantity calculation module is configured to combine the loop equation set and the network-structured inverter power supply fault equivalent model, and to solve the fault quantity by adopting an iterative calculation method according to the output power of the network-structured inverter power supply and the constraints of current characteristics, power and voltage relations.
9. A computer readable storage medium having stored thereon a computer program, which when executed by a processor, implements the steps of a method of fault simulation calculation of a grid-connected fan access system according to any of claims 1-7.
10. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor, when executing the program, performs the steps in a method of fault simulation calculation of a network-structured fan access system as claimed in any one of claims 1 to 7.

Description

Fault simulation calculation method and system for network-structured fan access system Technical Field The invention relates to the field of power system fault simulation modeling, in particular to a fault simulation calculation method and system of a grid-built fan access system. Background The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art. The traditional power grid fault analysis is generally based on a symmetrical component method and a superposition theorem, on the premise of power frequency steady-state assumption, by establishing an equivalent model of a power grid and combining fault types, fault point current and voltage distribution is calculated, but the method does not consider the access condition of different types of new energy sources, assumes that a system is in an ideal symmetrical state, and particularly has difficulty in representing the dynamic characteristics of nonlinear response and multisource collaborative interaction of power electronic equipment after the access of the network-structured new energy sources. The new energy is usually calculated in the form of constant current source or voltage source series impedance, and although the fault current contribution of the new energy can be partially reflected, the dynamic control logic of the power electronic equipment is ignored, so that the accuracy of a calculation result is poor. In fact, as a large number of synchronous machine power supplies are replaced by new energy sources, the conventional grid-following new energy sources cannot compensate for the problems of system inertia, strength and short-circuit capacity reduction. Regarding the fans, the grid-structured fans with voltage and frequency supporting capability can actively support the power grid, and become an important component in future power systems, and in the current research, fault simulation modeling and analysis calculation are performed on the system of virtual synchronous machine grid-structured fan power access, so that accurate electric quantity distribution conditions in the network under the power access condition cannot be obtained. In addition, after a large amount of new energy is accessed into the power grid, higher requirements are also put forward on the real-time simulation test of the power grid. Disclosure of Invention In order to overcome the defects of the existing fault simulation calculation technology, the invention provides a fault simulation calculation method and system of a network-structured fan access system, realizes rapid fault simulation after network-structured new energy access, and can be used for supporting a real-time simulation test technology of the new energy access system. To achieve the above object, one or more embodiments of the present invention provide the following technical solutions: in a first aspect, the present invention provides a fault simulation calculation method for a network fan access system, where the network fan includes a wind turbine body and a network inverter, and the method includes the following steps: based on a network-structured inverter control strategy of virtual synchronous machines, analyzing the characteristics of output power of the network-structured inverter in a steady state of power distribution network faults, and establishing an active and reactive power simulation calculation model of the network-structured inverter in the fault state; based on the network-structured inverter power supply fault equivalent model, establishing a composite sequence network equivalent model under the fault condition of the power distribution network containing the network-structured inverter power supply according to the network structure of the power distribution network; Based on the composite sequence net equivalent model, obtaining a loop equation set formed by a generalized matrix according to a circuit theorem; and the loop equation set and the network inverter power supply fault equivalent model are combined, and an iterative calculation method is adopted to solve the fault quantity according to the constraints of the output power, the current characteristics and the power-voltage relation of the network inverter power supply. According to a further technical scheme, the grid-structured inverter power supply adopts positive and negative sequence separation control, and the negative sequence loop adopts a control mode of inhibiting negative sequence current. According to a further technical scheme, when the power distribution network fails and is stable, the reactive power of the grid-formed inverter power supply meets the following formula: Wherein, the For the reactive power to be supplied,As a reference value for the reactive power,To reflect the voltage adjustment coefficient of the reactive-voltage sag characteristic,As a reference value for the system voltage,The voltage between the transformer