A network-constructing type power supply multi-machine transient stability control method based on inertia center frequency feedback

Abstract

The application discloses a kind of network type power supply multi-machine transient stability control methods based on inertia center frequency feedback, for the scene that short-circuit fault occurs in the regional power system containing synchronous generator and network type power supply equipment, first, the angular frequency of the internal potential phase angle of all synchronous generators or network type power supply in the system is calculated to obtain the inertia center frequency, and then, the power instruction value of the network type power supply equipment is adaptively adjusted according to the difference between the terminal voltage of the network type power supply equipment and the angular frequency and the inertia center frequency of the control system itself.

Description

Technical Field

[0001] This invention relates to the field of new energy power generation technology and grid connection control, specifically to a multi-machine transient stability control method for grid-connected power sources based on inertial center frequency feedback. This method is designed for AC system short-circuit fault scenarios and can achieve coordinated stability control of all grid-connected power source equipment in the system. Background Technology

[0002] The integration of large-scale new energy power generation equipment will weaken the grid strength, posing a severe challenge to the safe and stable operation of the new power system. Grid-based control, as a novel new energy grid-connected control technology, has become a feasible alternative to traditional main power sources due to its advantages in constructing AC voltage and possessing damping and inertial response capabilities, and has broad application prospects. To improve the dynamic synchronization performance of new energy grid-connected systems under grid disturbance conditions, enhance the fault ride-through capability of grid-based power generation units, and achieve stable grid-connected operation, it is necessary to study transient stability control strategies for grid-based power sources in multi-machine systems.

[0003] Currently, scholars both domestically and internationally have conducted relevant research on transient stability control strategies for network-type equipment, as exemplified by the following published literature:

[0004] [1] Wang Jilei, Zhang Xing, Zhu Qiaohua, et al. Transient stability analysis and control strategy of virtual synchronous generator [J]. Journal of Electrical Machines and Control, 2022, 26(12):28-37.

[0005] [2]GE PJ,TU CM,XIAO F,et al.Design-Oriented Analysis and TransientStability Enhancement Control for a Virtual Synchronous Generator[J].IEEETransactions on Industrial Electronics, 2022,70(3):2675-2684.

[0006] Reference [1] proposes a dynamic compensation method based on voltage amplitude deviation from the perspective of dynamic adjustment of power reference value. By adding a nonlinear compensation term for virtual power angle and voltage amplitude, the active power reference value of virtual synchronous generator is adaptively corrected, effectively suppressing the accumulation of power deviation during fault transient process. Reference [2] proposes a parameter adaptive adjustment strategy, which significantly improves the transient stability margin of the system under symmetrical fault by dynamically adjusting the virtual inertia and damping coefficient of grid-connected equipment during fault. However, existing research only focuses on single-machine grid-connected systems or multi-machine systems under a single control strategy, without considering the influence of multiple grid-connected power supply equipment and synchronous generators in the regional power grid. Further research is needed on the transient stability control method of multi-machine grid-connected power supply. Summary of the Invention

[0007] To address the aforementioned shortcomings of existing technologies, the present invention aims to propose a transient stability control strategy for grid-connected equipment in multi-machine scenarios involving synchronous generators and grid-connected power supplies. Based on the difference between the control system's own angular frequency and inertial center frequency, the power command value of the grid-connected power supply equipment is adaptively adjusted to improve the transient synchronization stability performance of the multi-machine system.

[0008] The technical solution of this invention is implemented as follows:

[0009] A method for transient stability control of a multi-machine grid-type power supply based on inertial center frequency feedback is proposed, comprising the following steps:

[0010] A1) When a short-circuit fault occurs in the system, the grid-connected power sources in the system will be switched to a fault control strategy. For all synchronous generators and grid-connected power sources in the regional power grid, their internal potential angular frequencies will be acquired in real time, and the inertial center angular frequency will be calculated using the following formula:

[0011]

[0012] In the formula: ω c ω is the angular frequency of the inertial center. x T is the angular frequency of the phase angle of the internal potential of the synchronous generator or grid-type power source with power source number x in the system. j_x It is the inertial time constant of the synchronous generator or grid-type power source with the power source number x in the system.

[0013] A2) The real-time inertial center frequency of each grid-type power source in the system is obtained, and the power command value of the grid-type power source is given by the following formula:

[0014]

[0015] Where: K C U is the power gain coefficient of the inertial center feedback quantity. N and U xThese are the rated terminal voltage and real-time terminal voltage of the grid-type power supply with power supply serial number x in the system, respectively. ref_x and P ref0_x These are the power command values ​​of the grid-type power supply with power supply number x in the system during the fault and the power command value at the initial moment before the fault, respectively.

[0016] Wherein, the power gain coefficient K C The value range is 0.5 to 20.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] This invention discloses a multi-machine transient stability control method for grid-connected power supplies based on inertial center frequency feedback. This method, through information exchange between multiple machines, enables the grid-connected power supply equipment in the system to effectively improve the synchronization stability of all units, including traditional synchronous machines, while ensuring its own stability. This invention can provide technical support for the grid-connected control of grid-connected power supply equipment and improve the overall safe and stable operation performance of new power systems. Attached Figure Description

[0019] Figure 1 This is a block diagram of the grid-type power supply control strategy based on inertial center frequency feedback according to the present invention.

[0020] Figure 2 The transient response simulation waveforms of the grid-type generating units and synchronous generators in the system are shown when a three-phase symmetrical fault occurs in the AC line of the system and the grid-type generating units adopt the traditional control strategy.

[0021] Figure 3 The transient response simulation waveforms of the grid-type generating units and synchronous generators in the system are shown when a three-phase symmetrical fault occurs in the AC line of the system and the grid-type generating units adopt the control strategy proposed in this method. Detailed Implementation

[0022] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0023] This invention proposes a multi-machine transient stability control method for grid-connected power sources based on inertial center frequency feedback, which is used to improve the transient synchronization stability of regional power grids containing grid-connected power source equipment. Figure 1 This is a block diagram of the grid-type power supply control strategy based on inertial center frequency feedback according to the present invention. Figure 2 The transient response simulation waveforms of the grid-type generating units and synchronous generators in the system are shown when a three-phase symmetrical fault occurs in the AC line of the system and the grid-type generating units adopt the traditional control strategy. Figure 3This figure shows the simulated transient response waveforms of the grid-connected generating units and synchronous generators in the system when a three-phase symmetrical fault occurs on the AC line and the grid-connected generating units adopt the control strategy proposed in this method. This method can improve the transient synchronization stability of all equipment in a regional power system containing synchronous generators and grid-connected power supply equipment experiencing a symmetrical short-circuit fault. This method adjusts the power command values ​​of the grid-connected power supply equipment based on the difference between inertial center frequencies, which can effectively improve the transient synchronization stability of the system.

[0024] The specific implementation steps of this invention are as follows:

[0025] A transient stability control method for multi-machine grid-type power sources based on inertial center frequency feedback is proposed, aiming to improve the transient synchronization stability of regional power grids.

[0026] A1) When a short-circuit fault is detected in the system, the grid-connected power sources in the system are switched to a fault control strategy. For all synchronous generators and grid-connected power sources in the regional power grid, the angular frequency of their internal potential phase angle is acquired in real time, and the inertial center angular frequency is calculated using the following formula:

[0027]

[0028] In the formula: ω c ω is the angular frequency of the inertial center. x T is the angular frequency of the phase angle of the internal potential of the synchronous generator or grid-type power source with power source number x in the system. j_x It is the inertial time constant of the synchronous generator or grid-type power source with the power source number x in the system.

[0029] A2) Based on the acquired inertial center frequency, each grid-type power source in the system gives the power command value of the grid-type power source according to the following formula:

[0030]

[0031] Where: K C U is the power gain coefficient of the inertial center feedback quantity. N and U x These are the rated terminal voltage and real-time terminal voltage of the grid-type power supply with power supply serial number x in the system, respectively. ref_x and P ref0_x These are the power command values ​​of the grid-type power supply with power supply number x in the system during the fault and the power command value at the initial moment before the fault, respectively.

[0032] Wherein, the gain coefficient K C The value range is 0.5 to 20.

[0033] Description of the effects of this invention:

[0034] Figure 2 The transient response waveforms of the grid-connected generating units and synchronous generators in a multi-unit power system are presented when a three-phase symmetrical fault occurs on an AC line and the grid-connected generating units adopt a traditional control strategy. Figure 2 It can be seen that due to the prolonged duration of the fault, the units in the system experienced relative loss of synchronization. Figure 3 This describes the transient response waveforms of the grid-connected generating units and synchronous generators in the system when a three-phase symmetrical fault occurs on the AC line and the grid-connected generating units adopt the control strategy proposed in this method. From... Figure 3 It can be seen that when the control strategy proposed in this invention is adopted, the units in the system can achieve synchronous stability. Therefore, the method proposed in this invention can significantly improve the transient synchronous stability of the system.

[0035] Finally, it should be noted that the above examples of the present invention are merely illustrative and not intended to limit the implementation of the invention. Although the applicant has described the present invention in detail with reference to preferred embodiments, those skilled in the art can make other variations and modifications based on the above description. It is impossible to exhaustively list all possible implementations here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A network configuration type power supply multi-machine transient stability control method based on inertia center frequency feedback, characterized in that, Follow these steps: A1) When a short-circuit fault occurs in the system, the grid-connected power sources in the system are switched to a fault control strategy; for all synchronous generators and grid-connected power sources in the regional power grid, the angular frequency of their respective internal potential phase angles is obtained in real time, and the inertial center angular frequency is calculated using the following formula: where ω c is the angular frequency of the center of inertia, ω x is the angular frequency of the internal voltage phase angle of the synchronous generator or grid-forming power source with serial number x in the system, T j_x is the inertia time constant of the synchronous generator or grid-forming power source with serial number x in the system; A2) Based on the acquired inertial center frequency, each grid-type power source in the system gives the power command value of the grid-type power source according to the following formula: Where: K C U is the power gain coefficient of the inertial center feedback quantity. N and U x These are the rated terminal voltage and real-time terminal voltage of the grid-type power supply with power supply serial number x in the system, respectively. ref_x and P ref0_x These are the power command values ​​of the grid-type power supply with power supply number x in the system during the fault and the power command value at the initial moment before the fault, respectively.

2. The network configuration type power supply multi-machine transient stability control method based on inertia center frequency feedback according to claim 1, characterized in that: The power gain coefficient K C is in the range 0.5-20.

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