MVDC power generation system control device based on feedforward desaturated DC transformer

Abstract

The present invention provides an MVDC power generation system control device based on a feedforward desaturated DC transformer, uses a feedforward desaturation method to build a DC transformer measurement system, uses two feedforward compensation loops including a DC transformer, measures the DC bus current through a DC transformer system, and converts the current measurement value into a voltage signal through the transformer principle and inputs it into a feedforward compensation controller of an auxiliary power generation system, thereby realizing the control of the DC bus current / voltage of the MVDC system, reducing the impact of pulse loads on the stability of the MVDC system of a fully electric large ship, and ensuring the ability of the large ship power system to quickly restore steady state. The present invention improves the dynamic performance of the DC transformer without affecting the steady-state performance of the DC transformer, such as the measurement accuracy, stability, time drift and temperature drift, so that the system maintains the high steady-state performance of the DC transformer when measuring the fluctuating bus current / voltage under the pulse load of the MVDC system.

Description

Technical Field

[0001] The invention belongs to the field of ship electrical technology, and in particular relates to a MVDC power generation system control device based on a feedforward desaturated DC transformer. Background Art

[0002] The medium voltage direct current (MVDC) integrated power system (MVDC system for short) of large ships has the advantages of high power density, high operating efficiency, and high operational flexibility. At present, my country's ship MVDC technology is in the engineering application stage, but there is still a problem of insufficient stability guarantee capability of the power system due to pulse loads. Due to the huge power in a very short time, the pulse load will basically put the system in a short-term repetitive non-periodic transient limit operation state, resulting in a large change in the DC bus voltage, which brings a huge impact to the power system. In the MVDC system of a large all-electric ship, the energy density, power density and impact of the pulse load on the power system are extremely huge, and there is a contradiction between the dynamic regulation characteristics of the DC bus voltage of the main power generation system of the all-electric ship MVDC and its stability. Therefore, controlling the DC bus voltage under extreme working conditions is a necessary means to ensure that the power system of large ships can quickly restore stability.

[0003] Feedforward compensation regulation is a powerful control method to achieve system stability, and the premise for implementing feedforward compensation is to perform high-precision real-time dynamic measurement of bus voltage / current that varies over a wide range. Therefore, a dynamic large voltage / current measurement sensor with high precision, large range, and excellent dynamic response performance is also crucial. As the current sensor with the highest existing measurement accuracy, extremely low temperature drift, high stability and high sensitivity, the DC transformer fully meets the needs of precise control of bus voltage. However, when facing large currents that change rapidly and dynamically, the DC transformer is prone to core saturation, which may cause sensor failure. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a MVDC power generation system control device based on a feedforward desaturated DC transformer, which is used to control the DC bus current / voltage of the MVDC system.

[0005] The technical solution adopted by the present invention to solve the above technical problems is: an MVDC power generation system control device based on a feedforward desaturated DC transformer, including a permanent magnet synchronous generator and a PWM-VSR rectifier, a DC bus, a DC transformer measurement system, a feedforward compensation controller, a PI controller, a decoupling controller and a SVPWM circuit; the output of the DC transformer measurement system is measured by The gain of the feedforward compensation controller is added to the stator current setpoint of the permanent magnet synchronous generator The DC transformer measurement system includes a DC transformer, a feedforward compensation current sensor, an excitation transformer, a demodulation filter system, a PI controller, and a signal conditioning amplifier circuit; the excitation transformer periodically outputs an excitation voltage U ex to the DC transformer, outputting square wave signals to the demodulation and filtering system; the DC bus outputs the DC bus current I L To the DC transformer and feedforward compensation current sensor, the DC transformer outputs a balance judgment signal u L To the demodulation and filtering system, the demodulation and filtering system extracts the characteristic voltage signal containing the measured DC bus current information and outputs it to the PI controller; the feedforward compensation current sensor output signal u f to the signal conditioning amplifier circuit, which outputs the signal to the DC transformer and serves as the total output voltage of the DC transformer measurement system.

[0006] According to the above scheme, the DC transformer includes a pair of differential cores and corresponding windings, secondary windings, and sampling resistors, which are used to accurately measure the bus current passing through the differential cores and convert it into a voltage signal through the sampling resistors.

[0007] According to the above scheme, the feedforward compensation current sensor includes a sensor element and a signal processing circuit; the sensor element uses a coreless current sensor based on magnetic field measurement to prevent the problem of DC transformer core saturation when facing dynamic current; the feedforward compensation current sensor is used to provide a reverse magnetic flux to the DC transformer core in real time according to the size of the measured current, so as to offset part of the magnetic flux of the DC transformer and prevent core saturation.

[0008] According to the above scheme, the demodulation and filtering system includes a frequency selection circuit, a filtering circuit, a square wave synchronization circuit and a phase-sensitive demodulation circuit; the demodulation and filtering system is used to extract the characteristic voltage signal containing the measured DC bus current information from the differential voltage signal output by the DC transformer and then input it into the PI controller.

[0009] According to the above scheme, the signal conditioning and amplifying circuit is used to filter and power amplify the output signals of the DC transformer and the feedforward compensation current sensor; the signal conditioning and amplifying circuit includes a power amplifier, and the power amplifier adopts a class AB linear amplifier.

[0010] According to the above scheme, let i q with i d are the stator current of the permanent magnet synchronous generator, and are the given values ​​of stator current, and are the control functions of the PI controller, and are the output functions of the decoupling controller respectively; the PI controller, decoupling controller, SVPWM circuit, permanent magnet synchronous generator and PWM-VSR rectifier connected in sequence constitute an auxiliary power generation system voltage-current inner loop controller adopting a PWM-VSR dual closed-loop current decoupling control structure, which is used to adjust the linear output voltage of the auxiliary power generation system when it is in a stable working state.

[0011] The beneficial effects of the present invention are:

[0012] 1. The MVDC power generation system control device based on the feedforward desaturated DC transformer of the present invention adopts a feedforward desaturation method to build a DC transformer measurement system, adopts two feedforward compensation loops including DC transformers, measures the DC bus current through the DC transformer system, and converts the current measurement value into a voltage signal through the transformer principle and inputs it into the feedforward compensation controller of the auxiliary power generation system, thereby realizing the control of the DC bus current / voltage of the MVDC system, reducing the influence of pulse load on the stability of the MVDC system of a fully electric large ship, and ensuring the ability of the large ship power system to quickly restore the steady state.

[0013] 2. The present invention improves the dynamic performance of the DC transformer without affecting the steady-state performance of the DC transformer, such as measurement accuracy, stability, time drift and temperature drift, thereby avoiding the saturation of the mutual inductance core of the transformer during the dynamic process, or quickly and automatically recovering the transformer measurement capability after the core is saturated, so that the system maintains the high steady-state performance of the DC transformer when measuring the fluctuating bus current / voltage under the pulse load of the MVDC system, and solves the problem of sensor failure caused by core saturation when the DC transformer faces a large current with rapid dynamic changes.

[0014] 3. The present invention converts the bus current measurement value obtained by the DC transformer measurement system into a voltage signal through the transformer principle and inputs it into the feedforward compensation controller of the auxiliary power generation system; the feedforward compensation controller uses the real-time voltage signal to generate an output, offsetting the impact of the pulse load current change on the DC bus voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the composition of a DC transformer measurement system according to an embodiment of the present invention.

[0016] Figure 2 It is a schematic diagram of the feedforward compensation control principle of the MVDC auxiliary power generation system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0018] See also Figure 1The DC transformer measurement system of the embodiment of the present invention includes a DC transformer, a feedforward compensation current sensor, an excitation transformer, and various signal processing circuits of a demodulation filter system, a PI controller, and a signal conditioning amplifier circuit. ex is the excitation voltage, I L is the DC bus current, u L is the balance judgment signal output by the DC transformer, u f is the output signal of the feedforward compensation current sensor, It is the output signal of the signal conditioning and amplifier circuit, representing the total output voltage of the DC transformer measurement system.

[0019] The excitation transformer is used to provide a periodic excitation voltage to the DC transformer and to provide a square wave signal required for phase-sensitive demodulation to the demodulation filter system.

[0020] The DC transformer mainly consists of a pair of differential cores and their corresponding windings, secondary windings and sampling resistors. It is used to accurately measure the bus current passing through the transformer core and convert it into a voltage signal through the sampling resistor.

[0021] The feedforward compensation current sensor mainly includes a sensor element and a signal processing circuit. In order to prevent the saturation problem of dynamic current, the sensor element uses a coreless current sensor based on magnetic field measurement. The feedforward compensation current sensor provides a reverse magnetic flux to the magnetic core in real time according to the magnitude of the measured current, which can offset part of the transformer flux and prevent the core from saturating. As a result, the DC transformer can withstand greater instantaneous current changes, greatly improving the dynamic performance of the transformer.

[0022] The demodulation and filtering system consists of a frequency selection circuit, a filtering circuit, a square wave synchronization circuit, and a phase-sensitive demodulation circuit. It is used to extract the characteristic voltage signal containing the measured bus current information from the differential voltage signal output by the DC transformer and then input it into the PI controller.

[0023] The signal conditioning amplifier circuit filters and amplifies the output of the DC transformer and the feedforward compensation current sensor. Considering that the switching ripple of the transistor will have a significant impact on the measurement accuracy of the DC transformer, the power amplifier in this patent solution uses a class AB linear amplifier.

[0024] like Figure 2 As shown in the figure, the feedforward compensation control loop of the MVDC system is mainly composed of the generator and its rectifier, DC bus, DC transformer measurement system, feedforward compensation controller, PI controller, decoupling controller and SVPWM circuit. L is the DC bus current, is the output voltage of the DC transformer measurement system, i q with i d is the stator current of the permanent magnet synchronous generator, and is the given value of stator current, and are the control actions of the PI controller respectively, and is the output function of the decoupling controller.

[0025] The permanent magnet synchronous generator and its rectifier, PI controller, decoupling controller, and SVPWM circuit constitute an auxiliary power generation system voltage-current inner loop controller using the classic PWM-VSR dual closed-loop current decoupling control structure, which is used to adjust the linear output voltage of the auxiliary power generation system when it is in a stable working state.

[0026] The DC transformer measurement system and the feedforward compensation controller form a nonlinear interference compensation module for the load current. The output of the DC transformer system is superimposed on the generator stator current through the feedforward compensation control gain. The method is used to utilize the measurement output signal of the bus voltage of the DC transformer system to offset the influence of the dynamic change of the pulse load current on the DC bus voltage.

[0027] The above embodiments are only used to illustrate the design ideas and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The protection scope of the present invention is not limited to the above embodiments. Therefore, any equivalent changes or modifications made based on the principles and design ideas disclosed by the present invention are within the protection scope of the present invention.

Claims

1. A control device for an MVDC power generation system based on a feedforward desaturated DC transformer, characterized in that: It includes permanent magnet synchronous generator and PWM-VSR rectifier, DC bus, DC transformer measurement system, feedforward compensation controller, PI controller, decoupling controller and SVPWM circuit; The output of the DC transformer measurement system is measured through The gain of the feedforward compensation controller is added to the stator current setpoint of the permanent magnet synchronous generator It is used to offset the influence of the dynamic change of pulse load current on the DC bus voltage by measuring and outputting the bus voltage signal; The DC transformer measurement system includes a DC transformer, a feedforward compensation current sensor, an excitation transformer, a demodulation filter system, a PI controller, and a signal conditioning amplifier circuit; The excitation transformer periodically outputs the excitation voltage U ex To the DC transformer, output square wave signal to the demodulation and filtering system; The DC bus outputs the DC bus current I L to the DC transformer and feedforward compensation current sensor, DC transformer output balance judgment signal u L To the demodulation filter system, The demodulation and filtering system extracts the characteristic voltage signal containing the measured DC bus current information and outputs it to the PI controller; Feedforward compensation current sensor output signal u f To the signal conditioning amplifier circuit, The signal conditioning and amplification circuits output signals respectively to the DC transformer and as the total output voltage of the DC transformer measurement system; The DC transformer includes a pair of differential cores and corresponding windings, a secondary winding, and a sampling resistor, which are used to accurately measure the bus current passing through the differential cores and convert it into a voltage signal through the sampling resistor; The feedforward compensation current sensor includes a sensor element and a signal processing circuit; the sensor element uses a coreless current sensor based on magnetic field measurement to prevent the DC transformer core saturation problem when facing dynamic current; The feedforward compensation current sensor is used to provide a reverse magnetic flux to the DC transformer core in real time according to the magnitude of the measured current, so as to offset part of the DC transformer's magnetic flux and prevent the core from saturation. The demodulation and filtering system includes a frequency selection circuit, a filtering circuit, a square wave synchronization circuit and a phase-sensitive demodulation circuit; The demodulation and filtering system is used to extract the characteristic voltage signal containing the measured DC bus current information from the differential voltage signal output by the DC transformer and then input it into the PI controller.

2. The MVDC power generation system control device based on feedforward desaturated DC transformer according to claim 1 is characterized in that: The signal conditioning and amplification circuit is used to filter and power amplify the output signals of the DC transformer and the feedforward compensation current sensor; The signal conditioning and amplifying circuit comprises a power amplifier, and the power amplifier adopts a class AB linear amplifier.

3. The MVDC power generation system control device based on feedforward desaturated DC transformer according to claim 1, characterized in that: set up i q with i d are the stator current of the permanent magnet synchronous generator, and are the given values ​​of stator current, and are the control functions of the PI controller, and are the output functions of the decoupling controller respectively; The PI controller, decoupling controller, SVPWM circuit, permanent magnet synchronous generator and PWM-VSR rectifier connected in sequence constitute an auxiliary power generation system voltage-current inner loop controller adopting a PWM-VSR double closed-loop current decoupling control structure, which is used to adjust the linear output voltage of the auxiliary power generation system when it is in a stable working state.

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