Marine digital automatic voltage regulator with voltage stabilization according to speed change

Abstract

The present invention relates to a digital automatic voltage regulator for ship with speed-dependent voltage stabilization, comprising an excitation regulator, a current transmitter and a contactor. The control function is realized by the excitation regulator, the current transmitter realizes the excitation current output, and the contactor device realizes the overvoltage protection and demagnetization functions. The digital automatic voltage regulator for ship with speed-dependent voltage stabilization controls the excitation current output of the AC exciter through a voltage feedback signal to control the output voltage stability of the main generator. Under the variable speed working condition of the ship rectifier generator, the real-time voltage at the generator end is collected and compared with the expected voltage value to generate a corresponding output, and the voltage at the generator end is controlled to be kept at the rated voltage within a certain speed range, thereby realizing the variable speed voltage stabilization function, which is of great significance for the vibration and noise reduction of the unit.

Description

Technical Field

[0001] The invention relates to the field of motor control, in particular to a marine digital automatic voltage regulator that stabilizes voltage as the speed changes. Background Art

[0002] With the development of technology, more and more ships in my country use DC power supply systems. Now ships have medium and low voltage levels, and AC and DC power systems coexist. Generators in large land power grid systems have widely used digital automatic voltage regulators, and many well-known foreign manufacturers have also developed related automatic voltage regulators.

[0003] The automatic voltage regulator is an important part of the generator. Its performance determines the operating characteristics of the generator and even the power system, ensuring the stability and safety of the generator and the power system. The functions of the automatic voltage regulator are mainly as follows: 1. Maintaining the stability of the generator terminal voltage; 2. Reasonable distribution of reactive power; 3. Improving the stability of the power system; 4. Improving the operating conditions of the power system.

[0004] Existing automatic voltage regulator products can control the generator terminal voltage to the rated voltage when the rectifier generator is at the rated speed. This is constant speed voltage stabilization. However, it cannot meet the requirement that the terminal voltage is stable at the rated voltage when the rectifier generator speed changes. It cannot control the voltage to be stable at the rated voltage when the rectifier generator speed decreases, that is, it cannot achieve voltage stabilization as the speed changes. Summary of the invention

[0005] Aiming at the problem that the commonly used rectifier generator automatic voltage regulator cannot achieve voltage stability with the change of speed, a marine digital automatic voltage regulator with voltage stability as the speed changes is proposed. On the basis of the existing digital automatic voltage regulator, in addition to realizing the functions of the conventional automatic voltage regulator, it can also achieve the rectifier generator speed drops to a certain range and still maintain the machine end voltage at the rated voltage.

[0006] The technical solution of the present invention is: a digital automatic voltage regulator for ship with voltage stabilization according to speed change, the alternating current output by the alternating current generator is converted into direct current through a rectifier, and the output of the alternating current exciter is rectified to provide direct current excitation for the alternating current generator, including an excitation regulator, a current and voltage acquisition unit, a conditioning circuit and a contactor K1;

[0007] The current and voltage acquisition unit includes a sampling transformer T2, a DC current sensor CT, a DC voltage sensor PT and a current transmitter U1; the sampling transformer T2 acquires the AC side voltage output by the AC generator, the DC current sensor CT and the DC voltage sensor PT acquire the DC side current and voltage values ​​of the rectifier device, and the current transmitter U1 acquires the DC excitation current output by the excitation regulator;

[0008] The conditioning circuit converts the collected DC current and voltage signals output by the rectifier device into analog DC voltage signals that can be received by the excitation regulator, and at the same time provides ±24V working power for the DC current sensor and voltage sensor used to collect signals; the conditioning circuit outputs the contactor K1 control signal, when the main contact of K1 is closed, the excitation is started, and the generator can generate electricity normally; when the main contact of K1 is disconnected, the excitation is de-excited;

[0009] The excitation regulator includes a control circuit, a sampling circuit, a power supply, a drive circuit and a power main circuit. The sampling circuit collects the excitation voltage and current and the analog DC voltage signal output by the conditioning circuit, converts the analog signal into a digital signal and transmits it to the control circuit for processing. The control circuit performs calculations based on the external control instructions and the numerical value of the sampling circuit, obtains a control signal and transmits it to the drive circuit. The drive circuit drives the power main circuit based on the control signal. Under the drive of the drive circuit, the power main circuit converts the excitation power supply into electric energy to obtain the excitation electric energy required by the exciter.

[0010] Preferably, the sampling circuit in the excitation regulator performs AD conversion on the analog DC voltage signal output by the conditioning circuit into a digital signal to obtain a machine-end voltage feedback signal, and then compares it with a given voltage value, and forms a deviation signal through control calculation. The deviation signal drives the on and off of the IGBT through the driving circuit to adjust the output excitation current, and the DC voltage at the generator end changes accordingly, so that the DC voltage at the generator end always tracks the given voltage.

[0011] Preferably, when the speed of the AC generator is within the range of 80% of the rated speed to the rated speed, the digital automatic voltage regulator sets the voltage set value to the machine-end DC voltage corresponding to the rated voltage of the generator. Within this speed range, the excitation regulator adjusts the excitation current through a control algorithm so that the generator-end DC voltage is stabilized at the rated voltage; when the generator speed is less than 80% of the rated speed, the voltage set value is given according to the V / F curve, the generator quickly builds up voltage, and at the same time prevents overshoot and overvoltage during voltage buildup.

[0012] The beneficial effects of the present invention are as follows: the digital automatic voltage regulator for ship-based voltage stabilization with speed changes of the present invention, under the variable speed working condition of the ship's rectifier generator, collects the real-time voltage at the generator end, compares it with the expected voltage value, generates a corresponding output, controls the generator end voltage to maintain the rated voltage within a certain speed range, realizes the variable speed voltage stabilization function, and is of great significance for the vibration and noise reduction of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The principle diagram of the digital automatic voltage regulator for ships of the present invention that stabilizes voltage as the speed changes;

[0014] Figure 2 It is a block diagram of the excitation regulator in the digital automatic voltage regulator of the present invention;

[0015] Figure 3 The present invention is a flowchart of the speed change voltage stabilization program in the digital automatic voltage regulator. DETAILED DESCRIPTION

[0016] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0017] The digital automatic voltage regulator for ship-borne voltage stabilization with speed change of the present invention comprises an excitation regulator, a current transmitter and a contactor, etc. The control function is realized by the excitation regulator, the current transmitter realizes the excitation current output, and the contactor and other devices realize the overvoltage protection and demagnetization functions. The digital automatic voltage regulator for ship-borne voltage stabilization with speed change controls the excitation current output of the AC exciter through a voltage feedback signal to control the output voltage stability of the main generator. The excitation mode of the generator can be selected as self-excitation or external excitation. If the excitation power supply of the self-excitation mode has low power, an external excitation power supply can be sought. The specification is a three-phase 380VAC power supply, and the power is adjusted according to different rectifier generators.

[0018] During the variable speed process of the rectifier generator, the marine digital automatic voltage regulator that stabilizes the voltage as the speed changes adjusts the voltage set value according to the different speeds, controls the excitation current, and realizes the variable speed voltage stabilization function within a certain speed range. When loaded, the speed drops within 80% of the rated speed to keep the voltage constant. At 80% of the rated speed, the maximum load that can be carried is 50% of the rated load.

[0019] The digital automatic voltage regulator for marine speed-dependent voltage regulation adopts the terminal voltage excitation mode. The AC exciter coaxial with the main generator provides DC excitation power to the main generator through a rotating rectifier. The digital automatic voltage regulator for marine speed-dependent voltage regulation achieves the purpose of controlling the excitation of the main generator by controlling the excitation current of the AC exciter. The digital automatic voltage regulator for marine speed-dependent voltage regulation can be arranged in the auxiliary outlet box of the generator base, and the voltage and current sensors for terminal voltage excitation can be arranged in the cooling air duct of the generator top cover.

[0020] The principle diagram of the digital automatic voltage regulator for marine use that stabilizes voltage as the speed changes is as follows: Figure 1As shown, GS is a twelve-phase AC generator, which can also be a six-phase AC generator; Z is a rectifier, which converts the AC power output by the GS generator into DC power; GF is an AC exciter, whose output provides excitation for the main generator GS after rectification. The excitation mode of this implementation scheme is external excitation, and the excitation power supply is an external three-phase 380VAC AC power supply. The excitation mode can also be selected as terminal voltage self-excitation or permanent magnet machine excitation mode. Figure 1 In the figure, the double-dotted frame is a digital automatic voltage regulator for marine use that stabilizes voltage as the speed changes. The excitation regulator is its control core, which realizes functions such as sampling, comparison, control, and output. It collects the DC voltage and current signals at the machine end, compares them with the given values, and outputs a deviation signal. The excitation regulator calculates and processes the deviation signal and outputs a control signal to the drive circuit. The drive power main circuit converts the excitation power supply into the excitation power supply required by the exciter.

[0021] Figure 1 In the circuit, the main function of the conditioning circuit is signal conversion, which converts the DC current and voltage signals output by the rectifier device into analog voltage signals that can be received by the excitation regulator. The conditioning circuit also provides ±24V working power for the DC current sensor and voltage sensor used to collect signals. U1 is a current transmitter, which converts the DC excitation current output by the excitation regulator into a 4-20mA signal and sends it to external equipment for display or fault judgment. K1 is a contactor that can realize the demagnetization and excitation functions. When the main contact of K1 is closed, it is excitation, and the generator can generate electricity normally; when the main contact of K1 is disconnected, it is demagnetization.

[0022] Figure 1 In the figure, the three-phase AC transformer T1 is an excitation transformer, which provides excitation energy for the generator. Its primary side is an external three-phase 380VAC AC power supply. After voltage reduction, the secondary side is output to the excitation regulator, and after chopped, it is supplied to the excitation winding. The three-phase AC transformer T2 is a sampling transformer, which collects the AC side voltage output by GS to measure frequency or fault judgment. CT is a DC current sensor, which collects the DC current signal at the machine end. PT is a DC voltage sensor, which collects the DC voltage signal at the machine end.

[0023] like Figure 2 The block diagram of the excitation regulator shown in the figure shows that the excitation regulator is composed of a control circuit, a sampling circuit, a power supply, a drive circuit and a power main circuit. The sampling circuit collects the excitation voltage and current and the voltage signal output by the conditioning circuit, converts the analog signal into a digital signal and transmits it to the control circuit for processing. The control circuit performs calculations based on the external control instructions and the value of the sampling circuit, obtains a control signal and transmits it to the drive circuit. The drive circuit drives the power main circuit based on the control signal. Under the drive of the drive circuit, the power main circuit converts the excitation power supply into electric energy to obtain the excitation electric energy required by the exciter.

[0024] During the variable speed of the rectifier generator, the marine digital automatic voltage regulator that stabilizes the voltage with the speed changes uses a digital signal processor DSP to implement the control algorithm, adjusts the voltage setting value according to different speeds, controls the excitation current, and realizes the variable speed voltage stabilization function within a certain speed range. The excitation regulator senses the generator speed by collecting the voltage on the secondary side of the sampling transformer T2; the rated output DC current of PT is ±50mA, reflecting the extreme DC voltage; the rated output DC current of CT is ±800mA, reflecting the DC current of the generator end; the conditioning circuit converts the DC current output by PT and CT into an analog DC voltage signal (the absolute value of the voltage signal is <15VDC) that can be received by the excitation regulator; the sampling circuit in the excitation regulator converts the analog DC voltage signal output by the conditioning circuit into a digital signal to obtain the machine end voltage feedback signal, and then compares it with the given voltage value, and forms a deviation signal through control calculation. The deviation signal drives the IGBT to turn on and off through the drive circuit to adjust the output excitation current, and the DC voltage at the generator end changes accordingly, so that the DC voltage at the generator end always tracks the given voltage. When the generator speed is within the range of 80% to the rated speed, the digital automatic voltage regulator sets the voltage setting value to the DC voltage at the generator end corresponding to the rated voltage of the generator. Within this speed range, regardless of whether the speed increases or decreases, the excitation regulator adjusts the excitation current through the control algorithm to stabilize the DC voltage at the generator end at the rated voltage. When the generator speed is less than 80% of the rated speed, the voltage setting value is given according to the V / F curve, which can ensure that the generator can quickly build up voltage and prevent overshoot and overvoltage during voltage building. The speed-changing voltage stabilization program flow chart of the marine digital automatic voltage regulator that stabilizes voltage as the speed changes is shown in the figure below. Figure 3 shown.

[0025] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A digital automatic voltage regulator for ships with speed-dependent voltage regulation, wherein the AC power outputted by the AC generator is converted into DC power by a rectifier, and the output of the AC exciter is rectified to provide DC excitation for the AC generator, characterized in that: It includes an excitation regulator, a current and voltage acquisition unit, a conditioning circuit and a contactor K1; The current and voltage acquisition unit includes a sampling transformer T2, a DC current sensor CT, a DC voltage sensor PT and a current transmitter U1; The sampling transformer T2 collects the AC side voltage output by the AC generator, the DC current sensor CT and the DC voltage sensor PT collect the DC side current and voltage values ​​of the rectifier, and the current transmitter U1 collects the DC excitation current output by the excitation regulator; The conditioning circuit converts the collected DC current and voltage signals output by the rectifier device into analog DC voltage signals that can be received by the excitation regulator, and at the same time provides ±24V working power for the DC current sensor and voltage sensor used to collect signals; the conditioning circuit outputs the contactor K1 control signal, when the main contact of K1 is closed, the excitation is started, and the generator can generate electricity normally; when the main contact of K1 is disconnected, the excitation is de-excited; The excitation regulator includes a control circuit, a sampling circuit, a power supply, a drive circuit and a power main circuit. The sampling circuit collects the excitation voltage and current and the analog DC voltage signal output by the conditioning circuit, converts the analog signal into a digital signal and transmits it to the control circuit for processing. The control circuit performs calculations based on the external control instructions and the numerical value of the sampling circuit, obtains a control signal and transmits it to the drive circuit. The drive circuit drives the power main circuit based on the control signal. Under the drive of the drive circuit, the power main circuit converts the excitation power supply into electric energy to obtain the excitation electric energy required by the exciter.

2. The digital automatic voltage regulator for marine use with voltage stabilization according to claim 1 is characterized in that: The sampling circuit in the excitation regulator performs AD conversion on the analog DC voltage signal output by the conditioning circuit to obtain a digital signal to obtain a machine-end voltage feedback signal, and then compares it with a given voltage value, and forms a deviation signal through control calculation. The deviation signal drives the on and off of the IGBT through the driving circuit to adjust the output excitation current, and the generator-end DC voltage changes accordingly, so that the generator-end DC voltage always tracks the given voltage.

3. The digital automatic voltage regulator for ships with speed-dependent voltage stabilization according to claim 2, characterized in that: When the speed of the AC generator is within the range of 80% of the rated speed to the rated speed, the digital automatic voltage regulator sets the voltage set value to the machine-end DC voltage corresponding to the rated voltage of the generator. Within this speed range, the excitation regulator adjusts the excitation current through a control algorithm so that the generator-end DC voltage is stabilized at the rated voltage. When the generator speed is less than 80% of the rated speed, the voltage set value is given according to the V / F curve, the generator quickly builds up voltage, and at the same time prevents overshoot and overvoltage during voltage buildup.

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