Protecting circuits and pitch systems

Abstract

An embodiment of the present application provides a protection circuit and a pitch control system for a wind turbine generator set, wherein an input interface of the protection circuit is connected to a power supply of a pitch control controller, and an output interface is connected to the pitch control controller, and the protection circuit comprises: a surge protection circuit, a main protection circuit, a switch circuit and a current sensor connected between the input interface and the output interface; the main protection circuit is used to clamp the control terminal voltage of the switch circuit when a surge is detected in the input voltage of the switch circuit, so that the output voltage of the switch circuit is limited within a specified voltage range; and when a transient overcurrent of the output current of the switch circuit is detected by the current sensor, the output current of the switch circuit is limited, or the switch circuit is controlled to be in a closed state; and when a continuous overvoltage of the input voltage of the switch circuit and / or a continuous overcurrent of the input current of the switch circuit are detected within a set time period, the switch circuit is controlled to be in a closed state.

Description

Technical Field

[0001] The present application relates to the technical field of wind power generation, and in particular to a protection circuit and a pitch control system. Background Art

[0002] The control core of the wind turbine pitch control system is the PLC (Programmable Logic Controller). Any problem with the PLC will have catastrophic consequences for the pitch control system and even the entire wind turbine. If there is a problem with the weak current system that supplies power to the PLC, the PLC will not be able to work properly.

[0003] The PLC is generally powered by a +24V power supply. When working, the reliability requirements of this power supply are relatively high, far exceeding the power supply requirements in the general industrial control field. An important factor affecting reliability is its anti-interference and anti-lightning surge capabilities.

[0004] Wind turbines are usually built in sparsely populated areas with harsh environments. They are particularly affected by lightning weather and are easily disturbed by surges during operation. Problems often occur in weak current power supply systems due to direct lightning, induced lightning, switching surges, etc.

[0005] The inventors of the present application studied the prior art and found that in order to improve the reliability of the power supply, the prior art usually installs a lightning surge protection module at the PLC power input end. Although the lightning surge protection module can solve some problems, there is a problem of high residual voltage of the output power supply, which will cause a large number of damages to key components such as the PLC during the thunderstorm season. In addition, the lightning surge protection module has a short lifespan and needs to be inspected and replaced regularly. Summary of the invention

[0006] In view of this, the present application provides a protection circuit and a pitch control system to solve the overvoltage, overcurrent and surge problems of the PLC power supply circuit and improve the reliability of the PLC power supply circuit.

[0007] In order to achieve the above objectives, this application provides the following technical solutions:

[0008] The embodiment of the present application provides a protection circuit for a wind turbine generator set, wherein the input interface of the protection circuit is connected to the power supply of the pitch controller, and the output interface is connected to the pitch controller, and the protection circuit comprises: an anti-surge protection circuit connected between the input interface and the output interface, a main protection circuit, a switch circuit, and a current sensor;

[0009] The input end of the surge protection circuit is connected to the input interface;

[0010] The control end of the switch circuit is connected to the main protection circuit, the input end is connected to the output end of the surge protection circuit and the main protection circuit, and the output end is connected to one end of the current sensor and the main protection circuit;

[0011] The other end of the current sensor is connected to the output interface and the main protection circuit;

[0012] The main protection circuit is used to clamp the control terminal voltage of the switching circuit when a surge is detected in the input voltage of the switching circuit, so that the output voltage of the switching circuit is limited to a specified voltage range; and when a transient overcurrent is detected in the output current of the switching circuit by the current sensor, the output current of the switching circuit is limited, or the switching circuit is controlled to be in a closed state; and when a continuous overvoltage and / or continuous overcurrent of the input voltage of the switching circuit is detected within a set time period, the switching circuit is controlled to be in a closed state.

[0013] Optionally, the main protection circuit includes an integrated circuit and a configuration circuit, and the configuration circuit is arranged outside the integrated circuit;

[0014] The configuration circuit includes a current limiting circuit and a switch threshold setting circuit;

[0015] One end of the current limiting circuit is connected to the input end of the switch circuit, and the other end is connected to the integrated circuit, and is used to cooperate with the integrated circuit to limit the current generated when the switch circuit is detected;

[0016] The switch threshold setting circuit has a first end connected to the control end of the switch circuit, a second end connected to the integrated circuit, and a third end connected to the ground end, and is used to cooperate with the integrated circuit to set the threshold of the switch circuit;

[0017] An integrated circuit is used to control the switch circuit to be in a closed state through a switch threshold setting circuit when it is detected that the input voltage of the switch circuit is continuously overvoltage and / or the input current of the switch circuit is continuously overcurrent within a set time period; and is used to clamp the control terminal voltage of the switch circuit through the switch threshold setting circuit when a surge occurs in the input voltage of the switch circuit, so that the output voltage of the switch circuit is limited to a specified voltage range.

[0018] Optionally, the configuration circuit further includes a fault setting circuit and a device protection circuit;

[0019] One end of the fault setting circuit is connected to the integrated circuit, and the other end is connected to the ground terminal, and is used to set the off time of the switch circuit and the cooling cycle of the integrated circuit when a fault occurs;

[0020] The first end of the device protection circuit is connected to the input end of the switching circuit, the second end is connected to the integrated circuit, and the third end is connected to the ground end. It is used to cooperate with the integrated circuit to protect the switching circuit and the current sensor when the integrated circuit detects that the input voltage of the switching circuit is continuously overvoltage and / or the input current of the switching circuit is continuously overcurrent within a set time period.

[0021] Optionally, the integrated circuit is configured with an automatic retry function.

[0022] Optionally, the current limiting circuit includes a first resistor; the switch threshold setting circuit includes a second resistor, a third resistor and a first capacitor; the fault setting circuit includes a second capacitor; the device protection circuit includes a fourth resistor, a third capacitor and a first unidirectional transient diode;

[0023] One end of the first resistor is connected to the integrated circuit, and the other end is connected to the input end of the switch circuit;

[0024] One end of the second resistor is connected to the control end of the switch circuit, and the other end is connected to the integrated circuit;

[0025] The third resistor and the first capacitor are connected in series between the other end of the second resistor and the ground terminal;

[0026] One end of the second capacitor is connected to the integrated circuit, and the other end is connected to the ground terminal;

[0027] One end of the fourth resistor is connected to the input end of the switch circuit, and the other end is connected to the integrated circuit, one end of the third capacitor and one end of the first unidirectional transient diode;

[0028] The other end of the third capacitor is connected to the ground, and the other end of the first unidirectional transient diode is connected to the ground.

[0029] Optionally, the configuration circuit further includes a second unidirectional transient diode, one end of the second unidirectional transient diode is connected to the other end of the second resistor, the other end of the second unidirectional transient diode is connected to the other end of the current sensor, and the other end of the current sensor is connected to the integrated circuit.

[0030] Optionally, the switch circuit is an N-type metal oxide semiconductor field effect transistor, and a gate of the metal oxide semiconductor field effect transistor is connected to a gate signal output terminal in the integrated circuit.

[0031] Optionally, the protection circuit further includes an energy storage circuit, which is connected between the current sensor and the output interface and is used to provide electrical energy to the pitch controller when the switch circuit is in a closed state.

[0032] Optionally, the energy storage circuit includes a plurality of supercapacitors connected in series in sequence, and for the two supercapacitors located at the two ends, one end of one of the supercapacitors is connected between the current sensor and the output interface, one end of the other supercapacitor is connected to the ground terminal, and each supercapacitor is provided with a resistor in parallel;

[0033] Or, the energy storage circuit includes a battery;

[0034] Alternatively, the energy storage circuit includes an emergency power supply.

[0035] Optionally, the surge protection circuit includes a first-level protection circuit, a delayed overcurrent protection circuit and a second-level protection circuit connected in series in sequence;

[0036] The first level protection circuit is used to absorb the energy generated by the surge to reduce the voltage value input to the time-delay overcurrent protection circuit;

[0037] A time-delay overcurrent protection circuit is used to prolong the transmission time of surge energy to the circuit connected after the time-delay overcurrent protection circuit when a surge comes;

[0038] The second level protection circuit is used to absorb the energy generated by the common mode surge and differential mode surge input through the delayed overcurrent protection circuit.

[0039] Optionally, the first-level protection circuit includes a gas discharge diode, a first end of the gas discharge diode is connected to the input interface, a second end is connected to the ground end, and a third end is connected to the protective ground end; or,

[0040] The first level protection circuit includes a varistor, one end of the varistor is connected to the input interface, and the other end is connected to the ground terminal.

[0041] Optionally, the delayed overcurrent protection circuit includes a fifth resistor, a sixth resistor, a first self-recovery fuse and a second self-recovery fuse;

[0042] The fifth resistor and the first self-recovery fuse are connected in series between the first end of the gas discharge diode and the second level protection circuit in sequence;

[0043] The sixth resistor and the second self-recovery fuse are connected in series between the second end of the gas discharge diode and the grounding end in sequence;

[0044] Or, the time-delay overcurrent protection circuit includes a first inductor, a second inductor, a first self-recovery fuse and a second self-recovery fuse;

[0045] The first inductor and the first self-recovery fuse are connected in series between the first end of the gas discharge diode and the second-level protection circuit in sequence;

[0046] The second inductor and the second self-recovery fuse are connected in series in sequence between the second end of the gas discharge diode and the ground end.

[0047] Optionally, the second-level protection circuit includes a first bidirectional transient diode, a second bidirectional transient diode and a third bidirectional transient diode;

[0048] A first bidirectional transient diode and a second bidirectional transient diode are connected in series, one end of the first bidirectional transient diode is connected to the first self-recovery fuse, one end of the second bidirectional transient diode is connected to the ground end, and a node between the first bidirectional transient diode and the second bidirectional transient diode is connected to the protection ground end;

[0049] The first bidirectional transient diode and the second bidirectional transient diode are connected in series and then connected in parallel with the third bidirectional transient diode.

[0050] Optionally, the input interface includes a first lead, a second lead, a third lead and a fourth lead;

[0051] The first lead is connected to the first-level protection circuit, and the first lead outputs the voltage value required by the pitch controller;

[0052] The second lead and the third lead are both connected to the shielding layer of the cable;

[0053] The fourth lead is connected to the ground terminal;

[0054] The output interface includes a fifth lead, a sixth lead, a seventh lead and an eighth lead;

[0055] The fifth lead and the sixth lead are both connected to the current sensor;

[0056] The seventh lead wire and the eighth lead wire are both connected to the ground terminal.

[0057] An embodiment of the present application also provides a pitch control system, including a pitch control controller, a power supply of the pitch control controller, and the above-mentioned protection circuit.

[0058] The beneficial effects brought by the technical solution provided in the embodiments of the present application include:

[0059] Therefore, the protection circuit provided in the embodiment of the present application can solve the overvoltage, overcurrent and surge problems of the power supply circuit of the pitch controller, and improve the reliability of the power supply circuit; and the protection circuit can ensure that the residual voltage is low enough, which plays a good protective role for the weak current system that is susceptible to interference, and greatly improves the reliability of the wind turbine generator set.

[0060] Additional aspects and advantages of the present application will be partially given in the following description, which will become apparent from the following description, or will be understood through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in describing the embodiments of the present application are briefly introduced below.

[0062] Figure 1 is a structural block diagram of a protection circuit provided in an embodiment of the present application;

[0063] Figure 2 is a structural block diagram of another protection circuit provided in an embodiment of the present application;

[0064] Figure 3 is a structural block diagram of another protection circuit provided in an embodiment of the present application;

[0065] Figure 4 It is a circuit structure diagram of a protection circuit provided in an embodiment of the present application.

[0066] The following describes the meanings of the various reference numerals in the embodiments of the present application:

[0067] 10-power supply of pitch controller; 11-input interface; 12-output interface; 13-pitch controller; 14-surge protection circuit; 15-main protection circuit; 16-switching circuit; 17-current sensor; 18-energy storage circuit;

[0068] 151-integrated circuit; 152-configuration circuit; 1521-current limiting circuit; 1522-switch threshold setting circuit; 1523-fault setting circuit; 1524-device protection circuit; 141-first level protection circuit; 142-delay overcurrent protection circuit; 143-second level protection circuit. DETAILED DESCRIPTION

[0069] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be interpreted as limiting the present application.

[0070] Those skilled in the art will appreciate that, unless expressly stated, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present application refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof. It should be understood that when we refer to an element as being "connected" to another element, it may be directly connected to the other element, or there may be intermediate elements. In addition, the "connection" used here may include wireless connections. The term "and / or" used here includes all or any unit and all combinations of one or more associated listed items.

[0071] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0072] First, several terms involved in this application are introduced and explained.

[0073] TVS: Transient Voltage Suppressor is a high-efficiency protection device in the form of a diode, which has an extremely fast response time (sub-nanosecond level) and a very high surge absorption capacity. When its two ends are subjected to a momentary high-energy impact, TVS can change the impedance value between the two ends from high impedance to low impedance at a very high speed to absorb a momentary large current and clamp the voltage at its two ends to a predetermined value, thereby protecting the subsequent circuit components from the impact of transient high-voltage spike pulses.

[0074] GDT: Gas Discharge Tube, is a discharge gap sealed in a ceramic cavity, which is filled with inert gas to stabilize the discharge voltage of the discharge tube. Its main features are large through-current energy, which can reach tens to hundreds of kiloamperes (KA), extremely high insulation resistance, no leakage, no aging failure, non-polarity bidirectional protection, and extremely small static capacitance. It is particularly suitable for the rough protection of high-speed network communication equipment. It can be widely used in the first-level lightning surge protection of various power and signal lines.

[0075] Supercapacitors, also known as electrochemical capacitors, double-layer capacitors, gold capacitors, and farad capacitors, are electrochemical components developed in the 1970s and 1980s that store energy through polarized electrolytes. Unlike traditional chemical power sources, they are a type of power source that is between traditional capacitors and batteries and has special properties. They mainly rely on double-layer and redox pseudocapacitive charges to store electrical energy. However, no chemical reaction occurs during the energy storage process, and this energy storage process is reversible. Because of this, supercapacitors can be charged and discharged repeatedly for hundreds of thousands of times.

[0076] Resettable fuse: an overcurrent electronic protection component, made of high molecular organic polymer under high pressure, high temperature, vulcanization reaction conditions, mixed with conductive particle materials, and processed by special technology. Traditional fuse overcurrent protection can only protect once, and needs to be replaced if it burns out, while resettable fuse has the dual functions of overcurrent and overheat protection and automatic recovery.

[0077] Residual voltage: Residual voltage is the peak voltage at the designated end of the protector when the discharge current flows through it. It can also be called the voltage between the terminals when the lightning discharge current passes through the lightning protection device.

[0078] Overvoltage: All electrical equipment has a rated voltage, but in practice, it cannot be completely guaranteed to work under the rated voltage. It is a range near the rated voltage, generally required to be ±15%. In order to protect electrical equipment and process quality, if it is higher than +15% of the rated voltage, it is "overvoltage".

[0079] Overcurrent: Overcurrent refers to current that exceeds the rated current of electrical equipment. Any loop current that is greater than the rated current-carrying capacity of the loop conductor is overcurrent, including overload current and short-circuit current. Among them: the overcurrent before the loop insulation is damaged is called overload current, and the overcurrent after the insulation is damaged is called short-circuit current.

[0080] A protection circuit provided in an embodiment of the present application is intended to solve the technical problems existing in the prior art.

[0081] The technical solution of the present application and how the technical solution of the present application solves the technical problems existing in the prior art are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0082] The present application embodiment provides a protection circuit, such as Figure 1 As shown, Figure 1 It is a structural block diagram of the protection circuit provided in an embodiment of the present application. The protection circuit is used for a wind turbine generator set. The input interface 11 of the protection circuit is connected to the power supply 10 of the pitch controller, and the output interface 12 is connected to the pitch controller 13. The protection circuit includes: an anti-surge protection circuit 14, a main protection circuit 15, a switch circuit 16 and a current sensor 17 connected between the input interface 11 and the output interface 12; the input end of the anti-surge protection circuit 14 is connected to the input interface 11; the control end of the switch circuit 16 is connected to the main protection circuit 15, the input end is connected to the output end of the anti-surge protection circuit 14 and the main protection circuit 15, and the output end is connected to one end of the current sensor 17 and the main protection circuit 15; the other end of the current sensor 17 is connected to the output interface 12 and the main protection circuit 15.

[0083] The main protection circuit 15 is used to clamp the control terminal voltage of the switch circuit 16 when a surge is detected in the input voltage of the switch circuit 16, so that the output voltage of the switch circuit 16 is limited to a specified voltage range; and when the output current of the switch circuit 16 is detected to be instantaneous overcurrent through the current sensor 17, the output current of the switch circuit 16 is limited, or the switch circuit 16 is controlled to be in a closed state; and when it is detected that the input voltage of the switch circuit 16 is continuously overvoltage and / or the input current of the switch circuit 16 is continuously overcurrent within a set time period, the switch circuit 16 is controlled to be in a closed state.

[0084] The input interface of the protection circuit provided in the embodiment of the present application is connected to the power supply of the pitch controller, and the output interface is connected to the pitch controller. The protection circuit includes: an anti-surge protection circuit, a main protection circuit, a switch circuit and a current sensor connected between the input interface and the output interface. When the main protection circuit detects a surge in the input voltage of the switch circuit, the control terminal voltage of the switch circuit is clamped so that the output voltage of the switch circuit is limited within a specified voltage range; and when the output current of the switch circuit is detected to be instantaneous overcurrent by the current sensor, the output current of the switch circuit is limited, or the switch circuit is controlled to be in a closed state; and when it is detected that the input voltage of the switch circuit is continuously overvoltage and / or the input current of the switch circuit is continuously overcurrent within a set time period, the switch circuit is controlled to be in a closed state. Therefore, the protection circuit provided in the embodiment of the present application can solve the overvoltage, overcurrent and surge problems of the PLC power supply circuit, and improve the reliability of the PLC power supply circuit; and the protection circuit can ensure that the residual voltage is low enough, which plays a good protective role for weak current systems such as PLC that are susceptible to interference, and greatly improves the reliability of the wind turbine generator set.

[0085] Alternatively, if Figure 2 As shown, the main protection circuit 15 in the embodiment of the present application includes an integrated circuit 151 and a configuration circuit 152, and the configuration circuit 152 is arranged outside the integrated circuit 151; the configuration circuit 152 includes a current limiting circuit 1521 and a switch threshold setting circuit 1522.

[0086] Specifically, one end of the current limiting circuit 1521 is connected to the input end of the switching circuit 16, and the other end is connected to the integrated circuit 151, and is used to cooperate with the integrated circuit 151 to limit the current generated when the switching circuit 16 is detected; the first end of the switch threshold setting circuit 1522 is connected to the control end of the switching circuit 16, the second end is connected to the integrated circuit 151, and the third end is connected to the ground end (not shown in the figure), and is used to cooperate with the integrated circuit 151 to set the threshold of the switching circuit 16.

[0087] Specifically, the integrated circuit 151 is used to control the switch circuit 16 to be in a closed state through the switch threshold setting circuit 1522 when it detects that the input voltage of the switch circuit 16 is continuously overvoltage and / or the input current of the switch circuit 16 is continuously overcurrent within a set time period; and is used to clamp the control terminal voltage of the switch circuit 16 through the switch threshold setting circuit 1522 when it detects that a surge occurs in the input voltage of the switch circuit 16, so that the output voltage of the switch circuit 16 is limited to a specified voltage range.

[0088] Alternatively, if Figure 2 As shown, the configuration circuit in the embodiment of the present application also includes a fault setting circuit 1523 and a device protection circuit 1524.

[0089] Specifically, one end of the fault setting circuit 1523 is connected to the integrated circuit 151, and the other end is connected to the ground end (not shown in the figure), and is used to set the shutdown time of the switch circuit 16 and the cooling cycle of the integrated circuit 151 when a fault occurs; the first end of the device protection circuit 1524 is connected to the input end of the switch circuit 16, the second end is connected to the integrated circuit 151, and the third end is connected to the ground end (not shown in the figure), and is used to cooperate with the integrated circuit 151 to protect the switch circuit 16 and the current sensor 17 when the integrated circuit 151 detects that the input voltage of the switch circuit 16 is continuously overvoltage and / or the input current of the switch circuit 16 is continuously overcurrent within a set time period.

[0090] In an optional implementation, the protection circuit provided in the embodiment of the present application further includes a storage circuit 18, such as Figure 3 As shown, the energy storage circuit 18 is connected between the current sensor 17 and the output interface 12, and is used to provide power to the pitch controller 13 when the switch circuit 16 is in the off state; the setting of the energy storage circuit in the embodiment of the present application can enable the pitch controller to power off and save data after a power problem occurs.

[0091] In an optional embodiment, if Figure 3 As shown, the surge protection circuit 14 in the embodiment of the present application includes a first-level protection circuit 141, a delayed overcurrent protection circuit 142 and a second-level protection circuit 143 which are connected in series in sequence; the first-level protection circuit 141 is used to absorb the energy generated by the surge to reduce the voltage value input to the delayed overcurrent protection circuit 142; the delayed overcurrent protection circuit 142 is used to extend the transmission time of the surge energy to the circuit connected after the delayed overcurrent protection circuit 142 when a surge comes; the second-level protection circuit 143 is used to absorb the energy generated by the common-mode surge and the differential-mode surge input through the delayed overcurrent protection circuit 142; the setting of the first-level protection circuit, the delayed overcurrent protection circuit and the second-level protection circuit in the embodiment of the present application can improve the reliability of the protection circuit.

[0092] The protection circuit provided in the embodiment of the present application is described in detail below with reference to a specific circuit diagram.

[0093] like Figure 4 As shown, Figure 41 is a circuit structure diagram of a protection circuit provided by a specific embodiment of the present application. The current limiting circuit 1521 in the embodiment of the present application includes a first resistor R6; a switch threshold setting circuit 1522 includes a second resistor R9, a third resistor R14 and a first capacitor C11; a fault setting circuit 1523 includes a second capacitor C16; a device protection circuit 1524 includes a fourth resistor R7, a third capacitor C10 and a first unidirectional transient diode D7. The second capacitor C16 is used to set the off time of the switch circuit 16 and the cooling cycle of the integrated circuit 151; wherein: the first unidirectional transient diode D7 plays a clamping protection role when the input voltage is over-voltage, and the fourth resistor R7 and the third capacitor C10 form an RC filter when encountering a short-duration spike, which plays a certain protective role on the circuit; the current generated when the drain and source of the N-type metal oxide semiconductor field effect transistor Q1 are detected flows through the first resistor R6, and the appropriate first resistor R6 can limit the current generated during the detection within a certain range under the peak input voltage condition.

[0094] Specifically, one end of the first resistor R6 is connected to the integrated circuit 151, and the other end is connected to the input end of the switch circuit 16; one end of the second resistor R9 is connected to the control end of the switch circuit 16, and the other end is connected to the integrated circuit 151; the third resistor R14 and the first capacitor C11 are connected in series between the other end of the second resistor R9 and the ground terminal GND; one end of the second capacitor C16 is connected to the integrated circuit 151, and the other end is connected to the ground terminal GND; one end of the fourth resistor R7 is connected to the input end of the switch circuit 16, and the other end is connected to the integrated circuit 151, one end of the third capacitor C10, and one end of the first unidirectional transient diode D7; the other end of the third capacitor C10 is connected to the ground terminal GND, and the other end of the first unidirectional transient diode D7 is connected to the ground terminal GND.

[0095] Alternatively, if Figure 4 As shown, the configuration circuit 152 in the embodiment of the present application also includes a second unidirectional transient diode D5, one end of the second unidirectional transient diode D5 is connected to the other end of the second resistor R9, and the other end is connected to the other end of the current sensor 17, and the other end of the current sensor is connected to the integrated circuit 151. The second unidirectional transient diode D5 plays a clamping protection role when the output voltage is over-voltage.

[0096] Alternatively, if Figure 4 As shown, the switch circuit 16 in the embodiment of the present application is an N-type metal oxide semiconductor field effect transistor, and the gate of the metal oxide semiconductor field effect transistor is connected to the gate signal output terminal of the integrated circuit 151. Of course, in practical applications, the switch circuit 16 can also select other types of thin film transistors.

[0097] Specifically, the embodiment of the present application adopts a dedicated integrated circuit 151, which can provide overvoltage and overcurrent protection functions of 4V to 72V. The design of the integrated circuit 151 and the series-connected N-type metal oxide semiconductor field effect transistor replaces the traditional protection circuit composed of large and bulky inductors, capacitors, TVS and fuses, thereby saving circuit board space and achieving continuous operation during transient power or current surges, which can protect downstream electronic components from input overvoltage damage up to the rated value of the N-type metal oxide semiconductor field effect transistor, and at the same time prevent the power supply from suffering output overload. In addition, the traditional protection circuit may cause the fuse to blow or burn the TVS, thus requiring maintenance, while the integrated circuit 151 in the embodiment of the present application can withstand a reverse input of up to 60V, which can play a good role in reverse protection.

[0098] Specifically, when the integrated circuit 151 of the embodiment of the present application detects a surge in the input voltage of the switching circuit 16, the integrated circuit 151 reduces the excessive voltage at the input and output ends of the switching circuit 16. At the same time, the switch threshold setting circuit 1522 clamps its gate voltage so that the output voltage of the switching circuit is limited to a specified voltage range. The specified voltage can be set according to the safety voltage requirements during actual design. In this way, downstream electronic components with lower rated voltages can be used, thereby saving costs.

[0099] Specifically, in the embodiment of the present application, during output overload or short circuit, the integrated circuit 151 limits the output current of the switch circuit 16, or controls the switch circuit 16 to be in a closed state, so that the forward path can be adjusted to a current limit value set by the current sensor 17. In addition, for continuous overvoltage and overcurrent, the setting of the integrated circuit 151 can control the switch circuit 16 to be turned off in a shorter time.

[0100] Specifically, since the integrated circuit 151 in the embodiment of the present application can suppress surges (overvoltage), and the essence of hot-plugging a circuit board is that the moment of plugging and unplugging brings a surge to the circuit, causing circuit damage, the integrated circuit 151 can also control the surge current during hot-plugging of the circuit board power supply.

[0101] Specifically, the integrated circuit 151 in the embodiment of the present application is configured to have an automatic retry function. After overvoltage or short-circuit protection, the circuit will automatically retry at intervals (such as 1 second). When it is detected that the overvoltage, short circuit, or reverse connection disappears, the switch circuit 16 will be turned on to connect the power supply to ensure that the subsequent circuit is restarted without human intervention. When it is detected that there is still overvoltage, overcurrent, or reverse connection, the switch circuit 16 is kept off so that the subsequent circuit is still in protection mode. This function is very suitable for variable pitch PLC applications. When the power supply fails, the service personnel cannot arrive at the site in time to deal with it. The self-diagnosis and self-retry function of this protection circuit saves the service personnel a lot of work and improves efficiency.

[0102] like Figure 4 As shown, the energy storage circuit 18 in the embodiment of the present application includes a plurality of super capacitors connected in series in sequence (the figure shows ten super capacitors C3, C4, C6, C7, C8, C9, C12, C13, C14 and C15), for the two super capacitors (C3 and C15) located at both ends, one end of C3 is connected between the current sensor 17 and the output interface 12, one end of C15 is connected to the ground terminal GND, and each super capacitor is connected to a resistor in parallel, and optionally, the resistance values ​​of all resistors are equal.

[0103] Of course, in actual design, the energy storage circuit 18 in the embodiment of the present application may also include a battery or an emergency power supply.

[0104] In specific implementation, supercapacitor C3 is connected in parallel with resistor R4, supercapacitor C4 is connected in parallel with resistor R5, supercapacitor C6 is connected in parallel with resistor R10, supercapacitor C7 is connected in parallel with resistor R11, supercapacitor C8 is connected in parallel with resistor R12, supercapacitor C9 is connected in parallel with resistor R13, supercapacitor C12 is connected in parallel with resistor R16, supercapacitor C13 is connected in parallel with resistor R17, supercapacitor C14 is connected in parallel with resistor R18, and supercapacitor C15 is connected in parallel with resistor R19. For example, the rated voltage value of the supercapacitor monomer selected in the embodiment of the present application is 2.7V, and the capacitance value is 2F. The energy storage system composed of the supercapacitor monomer can maintain a voltage drop of 2.4V and a power output of 2A / 200ms, providing emergency power supply for PLC emergency processing and recording.

[0105] like Figure 4 As shown, the first-level protection circuit 141 in the embodiment of the present application includes a gas discharge diode D2, a first end of the gas discharge diode D2 is connected to the input interface 11, a second end is connected to the ground end, and a third end is connected to the protection ground end PGND; of course, in actual design, a varistor can be used to replace the gas discharge diode D2. In specific implementation, one end of the varistor is connected to the input interface, and the other end is connected to the ground end.

[0106] Specifically, the main features of the gas discharge diode D2 used in the embodiment of the present application are large flow energy, which can reach tens to hundreds of KA, extremely high insulation resistance, no leakage, no aging failure, non-polarity bidirectional protection, and extremely small static capacitance. It is particularly suitable for the rough protection of high-speed network communication equipment and can be widely used in the first-level lightning surge protection of various power supplies and signal lines. The gas discharge diode D2 can provide effective protection for surges with a rise speed of 100V / s to 1000V / us. The parameters of the gas discharge diode D2 selected in the embodiment of the present invention are glow discharge voltage 75V to 200V and discharge current 5kA.

[0107] like Figure 4 As shown, the delayed overcurrent protection circuit 142 in the embodiment of the present application includes a fifth resistor R1, a sixth resistor R15, a first self-recovery fuse F1 and a second self-recovery fuse F2; the fifth resistor R1 and the first self-recovery fuse F1 are connected in series between the first end of the gas discharge diode D2 and the second-level protection circuit 143 in sequence; the sixth resistor R15 and the second self-recovery fuse F2 are connected in series between the second end of the gas discharge diode D2 and the ground terminal in sequence.

[0108] Of course, in actual design, inductors can be used instead of resistors. Specifically, the delayed overcurrent protection circuit 142 includes a first inductor (corresponding to the position of the fifth resistor R1), a second inductor (corresponding to the position of the sixth resistor R15), a first self-recovery fuse F1 and a second self-recovery fuse F2; the first inductor and the first self-recovery fuse are connected in series between the first end of the gas discharge diode and the second-level protection circuit in sequence; the second inductor and the second self-recovery fuse are connected in series between the second end of the gas discharge diode and the ground terminal in sequence.

[0109] Specifically, in the embodiment of the present application, the resistance of the fifth resistor R1 and the sixth resistor R15 is generally not more than 2 ohms, the power is not less than 1 watt, and the first resettable fuse F1 and the second resettable fuse F2 are selected to be 1A. The function of the delayed overcurrent protection circuit 142 is to form a delay circuit with resistors and resettable fuses. When a surge impact comes, the gas discharge diode D2 of the first-level protection circuit 141 is first activated to discharge and absorb most of the energy. After a certain discharge, the subsequent protection circuit can be activated to further reduce the voltage.

[0110] like Figure 4As shown, the second-level protection circuit 143 in the embodiment of the present application includes a first bidirectional transient diode D1, a second bidirectional transient diode D6 and a third bidirectional transient diode D4; the first bidirectional transient diode D1 and the second bidirectional transient diode D6 are connected in series, one end of the first bidirectional transient diode D1 is connected to the first self-recovery fuse F1, one end of the second bidirectional transient diode D6 is connected to the ground terminal, and the node between the first bidirectional transient diode D1 and the second bidirectional transient diode D6 is connected to the protection ground terminal PGND; the first bidirectional transient diode D1 and the second bidirectional transient diode D6 are connected in series and then connected in parallel with the third bidirectional transient diode D4.

[0111] Specifically, the reverse cutoff voltage of the first bidirectional transient diode D1, the second bidirectional transient diode D6 and the third bidirectional transient diode D4 in the embodiment of the present application is 33V, the power is 5KW, the first bidirectional transient diode D1 and the second bidirectional transient diode D6 protect the common-mode surge at the power input end, and the third bidirectional transient diode D4 protects the differential-mode surge at the power input end. The protection circuit composed of the first bidirectional transient diode D1, the second bidirectional transient diode D6 and the third bidirectional transient diode D4 can generally pass the standard surge test of 2KV.

[0112] like Figure 4 As shown, in the embodiment of the present application, the input interface 11 includes a first lead, a second lead, a third lead and a fourth lead; the first lead is connected to the first-level protection circuit 141, and the first lead outputs the voltage value required by the pitch controller; the second lead and the third lead are both connected to the shielding layer (PE) of the cable; the fourth lead is connected to the ground terminal; the output interface 12 includes a fifth lead, a sixth lead, a seventh lead and an eighth lead; the fifth lead and the sixth lead are both connected to the current sensor 17; the seventh lead and the eighth lead are both connected to the ground terminal. Since the input interface and the output interface of the protection circuit provided in the embodiment of the present application have only four wires, the wiring is simple, which is convenient for the transformation and upgrading of existing wind turbines.

[0113] Combine the following Figure 4 The working principle of the protection circuit provided in the embodiment of the present application is briefly introduced.

[0114] like Figure 4As shown, when a surge comes, the first-level protection circuit 141 first provides protection, and the first-level protection circuit 141 acts the fastest and absorbs the most energy; then, the RC circuit composed of the resistor R2 and the capacitor C5 filters out the high-frequency interference part, and plays a certain protective role for the switch circuit 16 and the integrated circuit 151; then, when the integrated circuit detects that the power supply voltage and current are normal, the switch circuit 16 is controlled to be stably in the open state, and when the current sensor 17 detects that the current is overcurrent, the switch circuit 16 is controlled to be in the closed state, or the output current of the switch circuit 16 is limited; when the integrated circuit detects that the input voltage of the switch circuit 16 is continuously overvoltage and / or the input current of the switch circuit 16 is continuously overcurrent within a set time period, the switch circuit 16 is controlled to be in the closed state.

[0115] like Figure 4 As shown, when the switch circuit 16 is normally turned on, the capacitors C1 and C2 play a filtering role to provide clean DC to the subsequent circuits, at which time the power indicator D3 lights up, and the resistor R3 plays a current limiting role. In addition, the resistor R8 is a current limiting resistor for the fault output of the integrated circuit 151.

[0116] In summary, the power supply of the pitch controller in the specific embodiment of the present application is connected to the pitch controller after passing through the protection circuit. The protection circuit is connected in series with the power supply of the pitch controller and the pitch controller. The protection circuit does not affect the function of the original circuit. The protection circuit has the following beneficial effects:

[0117] First, the protection circuit provided in the embodiment of the present application can solve the overvoltage, overcurrent and surge problems of the PLC power supply circuit, and improve the reliability of the PLC power supply circuit; and the protection circuit can ensure that the residual voltage is low enough, which plays a good protective role for weak current systems such as PLC that are susceptible to interference, and greatly improves the reliability of the wind turbine generator set.

[0118] Second, the protection circuit provided in the embodiment of the present application also includes an energy storage circuit, which can perform emergency data preservation after the main power supply is lost to facilitate subsequent fault analysis.

[0119] Third, the protection circuit provided in the embodiment of the present application includes an integrated circuit with an automatic restart function. After overvoltage or overcurrent protection, it will automatically restart at regular intervals to ensure that the subsequent circuit is restarted without human intervention.

[0120] Fourth, the protection circuit provided in the embodiment of the present application can withstand surge impact caused by hot plugging.

[0121] Fifth, the input interface and output interface of the protection circuit provided in the embodiment of the present application have only four wires, and the wiring is simple, which is convenient for the transformation and upgrading of existing wind turbines.

[0122] The above description is only a partial implementation method of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A protection circuit for a wind turbine generator set, characterized in that: The input interface (11) of the protection circuit is connected to the power supply (10) of the pitch controller, and the output interface (12) is connected to the pitch controller (13). The protection circuit comprises: an anti-surge protection circuit (14) connected between the input interface (11) and the output interface (12), a main protection circuit (15), a switch circuit (16), and a current sensor (17); The input end of the surge protection circuit (14) is connected to the input interface (11); The control end of the switch circuit (16) is connected to the main protection circuit (15), the input end is connected to the output end of the surge protection circuit (14) and the main protection circuit (15), and the output end is connected to one end of the current sensor (17) and the main protection circuit (15); The other end of the current sensor (17) is connected to the output interface (12) and the main protection circuit (15); The main protection circuit (15) is used to clamp the control terminal voltage of the switch circuit (16) when a surge is detected in the input voltage of the switch circuit (16), so that the output voltage of the switch circuit (16) is limited within a specified voltage range; and when the output current of the switch circuit (16) is detected to be transiently overcurrent through the current sensor (17), the output current of the switch circuit (16) is limited, or the switch circuit (16) is controlled to be in a closed state; and when the input voltage of the switch circuit (16) is detected to be continuously overvoltage and / or the input current of the switch circuit (16) is continuously overcurrent within a set period of time, the switch circuit (16) is controlled to be in a closed state.

2. The protection circuit according to claim 1, characterized in that: The main protection circuit (15) comprises an integrated circuit (151) and a configuration circuit (152), wherein the configuration circuit (152) is arranged outside the integrated circuit (151); The configuration circuit (152) includes a current limiting circuit (1521) and a switch threshold setting circuit (1522); One end of the current limiting circuit (1521) is connected to the input end of the switch circuit (16), and the other end is connected to the integrated circuit (151), and is used to cooperate with the integrated circuit (151) to limit the current generated when detecting the switch circuit (16); The switch threshold setting circuit (1522) has a first end connected to the control end of the switch circuit (16), a second end connected to the integrated circuit (151), and a third end connected to the ground end, and is used to cooperate with the integrated circuit (151) to set the threshold of the switch circuit (16); The integrated circuit (151) is used to control the switch circuit (16) to be in a closed state through a switch threshold setting circuit (1522) when it is detected that the input voltage of the switch circuit (16) is continuously over-voltage and / or the input current of the switch circuit (16) is continuously over-current within a set period of time; and is used to clamp the control terminal voltage of the switch circuit (16) through the switch threshold setting circuit (1522) when it is detected that a surge occurs in the input voltage of the switch circuit (16), so that the output voltage of the switch circuit (16) is limited within a specified voltage range.

3. The protection circuit according to claim 2, characterized in that: The configuration circuit (152) further includes a fault setting circuit (1523) and a device protection circuit (1524); One end of the fault setting circuit (1523) is connected to the integrated circuit (151), and the other end is connected to the ground end, and is used to set the off time of the switch circuit (16) and the cooling cycle of the integrated circuit (151) when a fault occurs; The device protection circuit (1524) has a first end connected to the input end of the switch circuit (16), a second end connected to the integrated circuit (151), and a third end connected to the ground end, and is used to cooperate with the integrated circuit (151) to protect the switch circuit (16) and the current sensor (17) when the integrated circuit (151) detects that the input voltage of the switch circuit (16) is continuously over-voltage and / or the input current of the switch circuit (16) is continuously over-current within a set time period.

4. The protection circuit according to claim 2, characterized in that: The integrated circuit (151) is configured to have an automatic retry function.

5. The protection circuit according to claim 3, characterized in that: The current limiting circuit (1521) comprises a first resistor; the switch threshold setting circuit (1522) comprises a second resistor, a third resistor and a first capacitor; the fault setting circuit (1523) comprises a second capacitor; the device protection circuit (1524) comprises a fourth resistor, a third capacitor and a first unidirectional transient diode; One end of the first resistor is connected to the integrated circuit (151), and the other end is connected to the input end of the switch circuit (16); One end of the second resistor is connected to the control end of the switch circuit (16), and the other end is connected to the integrated circuit (151); The third resistor and the first capacitor are connected in series between the other end of the second resistor and the ground terminal; One end of the second capacitor is connected to the integrated circuit (151), and the other end is connected to the ground end; One end of the fourth resistor is connected to the input end of the switch circuit (16), and the other end is connected to the integrated circuit (151), one end of the third capacitor and one end of the first unidirectional transient diode; The other end of the third capacitor is connected to the ground, and the other end of the first unidirectional transient diode is connected to the ground.

6. The protection circuit according to claim 5, characterized in that: The configuration circuit (152) also includes a second unidirectional transient diode, one end of which is connected to the other end of the second resistor, and the other end of which is connected to the other end of the current sensor (17), and the other end of the current sensor (17) is connected to the integrated circuit (151).

7. The protection circuit according to claim 6, characterized in that: The switch circuit (16) is an N-type metal oxide semiconductor field effect transistor, and the gate of the metal oxide semiconductor field effect transistor is connected to the gate signal output terminal in the integrated circuit (151).

8. The protection circuit according to any one of claims 1 to 7, characterized in that: It also includes an energy storage circuit (18), which is connected between the current sensor (17) and the output interface (12) and is used to provide electrical energy to the pitch controller (13) when the switch circuit (16) is in a closed state.

9. The protection circuit according to claim 8, characterized in that: The energy storage circuit (18) comprises a plurality of supercapacitors connected in series in sequence, wherein for the two supercapacitors located at the two ends, one end of one of the supercapacitors is connected between the current sensor (17) and the output interface (12), one end of the other supercapacitor is connected to the ground, and each of the supercapacitors is provided with a resistor in parallel; Or, the energy storage circuit (18) includes a battery; Alternatively, the energy storage circuit (18) includes an emergency power supply.

10. The protection circuit according to claim 1, characterized in that: The surge protection circuit (14) comprises a first-level protection circuit (141), a delayed overcurrent protection circuit (142) and a second-level protection circuit (143) which are connected in series in sequence; The first-level protection circuit (141) is used to absorb energy generated by surges to reduce a voltage value input to the time-delay overcurrent protection circuit (142); The time-delay overcurrent protection circuit (142) is used to prolong the transmission time of surge energy to the circuit connected after the time-delay overcurrent protection circuit (142) when a surge occurs; The second-level protection circuit (143) is used to absorb energy generated by common-mode surge and differential-mode surge input through the delayed overcurrent protection circuit (142).

11. The protection circuit according to claim 10, characterized in that: The first-level protection circuit (141) comprises a gas discharge diode, wherein a first end of the gas discharge diode is connected to the input interface (11), a second end is connected to a ground terminal, and a third end is connected to a protective ground terminal; or, The first-level protection circuit (141) comprises a varistor, one end of which is connected to the input interface (11), and the other end of which is connected to a ground terminal.

12. The protection circuit according to claim 11, characterized in that: The delayed overcurrent protection circuit (142) comprises a fifth resistor, a sixth resistor, a first self-recovery fuse and a second self-recovery fuse; The fifth resistor and the first self-recovery fuse are connected in series between the first end of the gas discharge diode and the second-level protection circuit (143); The sixth resistor and the second self-recovery fuse are connected in series between the second end of the gas discharge diode and the ground end; Or, the delayed overcurrent protection circuit includes a first inductor, a second inductor, a first self-recovery fuse and a second self-recovery fuse; The first inductor and the first self-recovery fuse are connected in series between the first end of the gas discharge diode and the second-level protection circuit (143); The second inductor and the second self-recovery fuse are connected in series between the second end of the gas discharge diode and the ground end.

13. The protection circuit according to claim 12, characterized in that: The second-level protection circuit (143) includes a first bidirectional transient diode, a second bidirectional transient diode and a third bidirectional transient diode; The first bidirectional transient diode and the second bidirectional transient diode are connected in series, one end of the first bidirectional transient diode is connected to the first self-recovery fuse, one end of the second bidirectional transient diode is connected to the ground end, and a node between the first bidirectional transient diode and the second bidirectional transient diode is connected to a protective ground end; The first bidirectional transient diode and the second bidirectional transient diode are connected in series and then connected in parallel with the third bidirectional transient diode.

14. The protection circuit according to claim 10, characterized in that: The input interface (11) comprises a first lead, a second lead, a third lead and a fourth lead; The first lead is connected to the first-level protection circuit (141), and the first lead outputs the voltage value required by the pitch controller; The second lead and the third lead are both connected to the shielding layer of the cable; The fourth lead is connected to the ground terminal; The output interface (12) comprises a fifth lead, a sixth lead, a seventh lead and an eighth lead; The fifth lead and the sixth lead are both connected to the current sensor (17); The seventh lead and the eighth lead are both connected to the ground terminal.

15. A variable pitch system, characterized in that: It comprises a pitch controller (13), a power supply (10) of the pitch controller, and a protection circuit as claimed in any one of claims 1 to 14.

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