阅读说明：本技术 一种不平衡电网中异步化调相机的比例积分谐振控制方法 (Proportional-integral resonance control method for asynchronous phase modulator in unbalanced power grid ) 是由 刘志鹏 蔡南 朱学成 徐明宇 陈晓光 郝文波 荣爽 刘进 刘延龙 张睿 于 2021-10-08 设计创作，主要内容包括：一种不平衡电网中异步化调相机的比例积分谐振控制方法,属于异步化调相机交流励磁控制领域,本发明用以解决现有技术中的异步化调相机控制方法复杂的问题,本发明包括异步化调相机的的有功功率和无功功率分别与有功功率给定值和无功功率给定值作差,经比例积分谐振控制得到异步化调相机的转子励磁电流dq轴分量参考值；转子电流的dq轴分量参考值分别与转子电流的dq轴分量作差后经比例积分谐振控制得到励磁电压的dq轴参考值；本发明可以有效的抑制由电网电压不平衡而使异步化调相机产生的二倍频功率脉动。(The invention relates to a proportional-integral resonance control method of an asynchronous phase modulator in an unbalanced power grid, belonging to the field of alternating current excitation control of the asynchronous phase modulator, and aiming at solving the problem that the control method of the asynchronous phase modulator in the prior art is complex; respectively subtracting the dq axis component reference value of the rotor current from the dq axis component of the rotor current, and then obtaining the dq axis reference value of the excitation voltage through proportional-integral resonance control; the invention can effectively restrain the double frequency power pulsation generated by the asynchronous phase modulator due to the unbalanced voltage of the power grid.)

1. A proportional-integral resonance control method of an asynchronous phase modulator in an unbalanced power grid is characterized by comprising the following steps:

s1, according to the terminal voltage U of the phase modulator_sabcAnd stator current I_sabcCalculating the active power P of the asynchronous phase modulator_sAnd reactive power Q_sActive power P of said asynchronous phase modulator_sAnd reactive power Q_sRespectively corresponding to given value P of active power_refAnd given value of reactive power Q_refObtaining a rotor exciting current dq axis component reference value i of the asynchronous phase modulator through proportional-integral resonance control_rdref、i_rqref；

S2 rotor current I to asynchronous phase modulator_rabcReference value i of dq axis component of_rdref、i_rqrefRespectively with the dq-axis component i of the rotor current_rd、i_rqObtaining a dq axis reference value u of the excitation voltage through proportional integral resonance control after difference_rdref、u_rqref；

S3, dq axis reference value u of excitation voltage_rdref、u_rqrefAnd applying the excitation voltage to the rotor excitation winding after coordinate transformation and SPWM modulation.

2. The PI resonance control method for asynchronous condenser in unbalanced networks as claimed in claim 1 wherein said rotor current I_rabcDq axis component i of_rd、i_rqThe obtaining method comprises the following steps:

according to the terminal voltage U of an asynchronous phase modulator_sabcObtaining the stator electric field rotation position angle theta of the asynchronous phase modulator₁And rotor angular velocity ω_rFor the angular speed ω of the rotor_rIntegrating to obtain the rotor position angle theta_rObtaining the position angle theta₁-θ_r；

The rotor current I_rabcAngle theta with respect to said position₁-θ_rObtaining dq axis component i by park transformation_rd、i_rq。

3. The proportional-integral resonance control method for the asynchronous phase modulator in the unbalanced power grid according to claim 1, wherein the continuous domain transfer function of the proportional-integral resonance link is as follows:

4. the proportional-integral resonance control method for the asynchronous condenser in the unbalanced power network as claimed in claim 1, wherein the reference value of the dq axis of the excitation voltage is obtained by:

Technical Field

The invention relates to an alternating current excitation control method of an asynchronous phase modulator, in particular to a proportional-integral resonance control method of the asynchronous phase modulator in an unbalanced power grid.

Background

The asynchronous phase modulator has no mechanical load on an axis during operation, is mainly used for providing reactive output for a system, has outstanding advantages in reactive output capacity and speed as a reactive compensation device, and the small-sized distributed phase modulator developed by a plurality of mechanisms at home and abroad at present increases synchronous inertia for a new energy system, but provides frequency support for the system, the main principle is the inherent coupling relation between rotating speed and system frequency, the inertia which can be provided is limited, and the inertia release size cannot be actively controlled.

The working occasion of the asynchronous phase modulator is a new energy power grid, inertia support and reactive compensation are provided for the new energy power grid, the fault with the highest frequency in the power system is a single-phase grounding short-circuit fault, negative sequence current can be generated when the power grid has such an unbalanced fault, a frequency doubling component is generated in a frequency converter of the asynchronous phase modulator through coordinate transformation, and the traditional PI control can only control a direct current component after park transformation, so that the frequency doubling power component in a controller can enable the phase modulator to generate double-frequency power pulsation, the phase modulator to generate heat, the quality of electric energy to be poor, and the stability of the system is influenced.

Disclosure of Invention

In order to overcome the technical problem, the invention provides a proportional-integral resonance control method of an asynchronous phase modulator in an unbalanced power grid, which has the effect of overcoming the defect that the excitation control of the existing asynchronous phase modulator cannot inhibit the double-frequency power pulsation in an excitation controller.

The invention provides a proportional-integral resonance control method of an asynchronous phase modulator in an unbalanced power grid, which comprises the following steps:

s1, according to the terminal voltage U of the phase modulator_sabcAnd stator current I_sabcCalculating the active power P of the asynchronous phase modulator_sAnd reactive power Q_sActive power P of said asynchronous phase modulator_sAnd reactive power Q_sRespectively corresponding to given value P of active power_refAnd given value of reactive power Q_refObtaining a rotor exciting current dq axis component reference value i of the asynchronous phase modulator through proportional-integral resonance control_rdref、i_rqref；

S2 rotor current I to asynchronous phase modulator_rabcReference value i of dq axis component of_rdref、i_rqrefRespectively with the dq-axis component i of the rotor current_rd、i_rqObtaining a dq axis reference value u of the excitation voltage through proportional integral resonance control after difference_rdref、u_rqref；

S3, dq axis of excitation voltageReference value u_rdref、u_rqrefThe excitation voltage is applied to the rotor excitation winding after coordinate transformation and SPWM modulation, and double frequency power pulsation is suppressed.

Preferably, the rotor current I_rabcDq axis component i of_rd、i_rqThe obtaining method comprises the following steps:

according to the terminal voltage U of an asynchronous phase modulator_sabcObtaining the stator electric field rotation position angle theta of the asynchronous phase modulator₁And rotor angular velocity ω_rFor the angular speed ω of the rotor_rIntegrating to obtain the rotor position angle theta_rObtaining the position angle theta₁-θ_r；

The rotor current I_rabcAngle theta with respect to said position₁-θ_rObtaining dq axis component i by park transformation_rd、i_rq。

Preferably, the continuous domain transfer function of the proportional-integral resonance element is as follows:

preferably, the excitation voltage dq axis reference value is obtained by the following method:

compared with the prior art, the invention has the following beneficial effects:

the invention adopts a proportional-integral resonance control method to control the asynchronous phase modulator, and can effectively inhibit the double-frequency power pulsation generated by the asynchronous phase modulator due to the unbalance of the voltage of a power grid by changing the resonance frequency in the control process; the control link of the invention does not have the traditional positive and negative sequence separation link, thereby avoiding the consequences of asynchronous phase modifier control delay, dynamic response variation and the like caused by the positive and negative sequence separation and improving the dynamic performance of the system; the invention adds a resonance control process on the basis of a proportional-integral link in the prior art, has simple control process, easy realization and wide application range, and can effectively inhibit double-frequency power pulsation.

Drawings

FIG. 1 is a schematic diagram of the overall principle of proportional-integral resonance control of an asynchronous phase modulator according to an embodiment of the present invention;

FIG. 2 is a simulated waveform diagram comparing proportional-integral resonance control with a conventional control method for an asynchronous phase modulator when a power grid voltage is unbalanced according to an embodiment of the present invention;

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order to make the advantages of the technical solutions of the present invention clearer, the present invention is described in detail below with reference to the accompanying drawings and examples.

The proportional-integral resonance control method for the asynchronous phase modulator in the unbalanced power grid, as shown in fig. 1, includes the following steps:

s1, according to the terminal voltage U of the phase modulator_sabcAnd stator current I_sabcCalculating the active power P of the asynchronous phase modulator_sAnd reactive power Q_sActive power P of said asynchronous phase modulator_sAnd reactive power Q_sRespectively corresponding to given value P of active power_refAnd given value of reactive power Q_refObtaining a rotor exciting current dq axis component reference value i of the asynchronous phase modulator through proportional-integral resonance control_rdref、i_rqref；

S2 rotor of asynchronous phase modifierCurrent I_rabcReference value i of dq axis component of_rdref、i_rqrefRespectively with the dq-axis component i of the rotor current_rd、i_rqObtaining a dq axis reference value u of the excitation voltage through proportional integral resonance control after difference_rdref、u_rqref；

As shown in FIG. 1, the rotor current I in the present embodiment_rabcDq axis component i of_rd、i_rqThe acquisition method comprises the following steps:

according to the terminal voltage U of an asynchronous phase modulator_sabcObtaining the stator electric field rotation position angle theta of the asynchronous phase modulator₁And rotor angular velocity ω_rFor the angular speed ω of the rotor_rIntegrating to obtain the rotor position angle theta_rObtaining the position angle theta₁-θ_r；

The rotor current I_rabcAngle theta with respect to said position₁-θ_rObtaining dq axis component i by park transformation_rd、i_rq。

In the present embodiment, the excitation voltage dq axis reference value is obtained by the following method:

s3, dq axis reference value u of excitation voltage_rdref、u_rqrefThe excitation voltage is applied to the rotor excitation winding after coordinate transformation and SPWM modulation, and double frequency power pulsation is suppressed.

In this embodiment, the continuous domain transfer function of the proportional-integral resonant element described in steps S1-S2 is:

to further verify the invention, in a specific embodiment, an asynchronous phase modulator with 50MW and a rated voltage of 10.5kV is selected for simulation, when the voltage of the power grid is in a balanced state for 2s-2.4s, the voltage of the a-phase drops by 50% at 2.4s, the power grid is in an unbalanced state, at this time, the phase modulator is still in proportional-integral (PI) control, and at 2.8s, the phase modulator is switched to proportional-integral resonance control. The simulation shows that each electrical parameter of the phase modulator effectively inhibits the frequency doubling component after the proportional-integral resonance control is adopted.

As described above, according to the excitation control method, the frequency doubling component generated by the phase modulator due to the unbalanced network voltage can be effectively weakened, the power quality is effectively improved, and the phase modulator is protected.

While embodiments of the invention have been disclosed above, it is not limited to the applications listed in the description and the examples, which are fully applicable in various fields of endeavor to which this invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.