Hybrid current source type excitation device based on half-control and full-control devices and control method
By adopting a hybrid current source excitation device of half-controlled and fully controlled devices in the generator excitation system, combining the parallel excitation main channel and series compensation channel, the low power factor, harmonic pollution and slow response speed in traditional excitation systems are solved. The problem has achieved rapid response to faults and emergencies and efficient power management, improving system stability and power quality.
Patent Information
- Application Number
- CN202411383630.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2024-12-31
AI Technical Summary
In traditional generator excitation systems, thyristor rectifiers cannot meet the needs of modern power systems for fast response and high-quality electrical energy due to low power factor, large harmonic pollution and slow response speed. At the same time, the full control excitation system is costly and complex, which is limited. Its wide application.
Using a hybrid current source excitation device based on half-control and full-control devices, the parallel excitation main converter and series compensation converter are combined, and the parallel excitation main channel and series compensation channel are formed by using half-control devices and full-control devices. , realize efficient absorption and injection of reactive power, and adjust the excitation current by controlling the switching signal.
While maintaining high power processing capabilities and cost advantages, we can improve the system's response ability to faults and emergencies, improve system stability and power quality, and enhance dynamic response performance and voltage stability.
Smart Images
Figure CN119231982A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of electric power systems, and more specifically, relates to a hybrid current source excitation device based on semi-controlled and fully-controlled devices and a control method. Background Art
[0002] The performance of the generator excitation system has a direct impact on the stable operation and power quality of the generator. With the development of the power system and the improvement of the power quality requirements, the improvement of the generator excitation system has become an important issue to ensure the stable and efficient operation of the power system. The traditional generator excitation system mainly adopts a self-parallel excitation system composed of thyristors. This system has been widely used due to its high power handling capacity and low cost. However, thyristor rectifiers have several disadvantages, such as low power factor, large harmonic pollution, slow response speed, etc., which cannot fully meet the needs of modern power systems for fast response and high-quality electricity.
[0003] During operation, thyristor rectifiers will generate large harmonics due to their phase control method. These harmonics will not only reduce the power factor of the system, but also have an adverse effect on the power grid and increase the electromagnetic interference of the system. At the same time, the response speed of the thyristor during the conduction and shutdown process is relatively slow, making it difficult for the system to quickly adjust the excitation current, thereby affecting the dynamic performance and stability of the generator. In addition, when the power system fluctuates frequently, thyristor rectifiers often find it difficult to achieve fast and stable reactive power regulation, resulting in a decrease in the overall stability of the system.
[0004] Relatively speaking, the fully controlled excitation system composed of fully controlled devices (such as IGBT, GTO) performs well in many aspects. The fully controlled device excitation system can achieve advantages such as high power factor, low harmonics and fast response, which makes it popular in some applications with high performance requirements. For example, IGBT has high switching speed and good control characteristics, and can achieve precise current control through PWM (pulse width modulation) technology, thereby significantly improving the dynamic response performance and power quality of the system. However, there are also some challenges in the fully controlled excitation system, such as high cost, strict thermal management requirements and complex control algorithms. These factors limit its widespread application in large-capacity excitation systems. Despite this, the advantages of the fully controlled excitation system in improving power quality and response speed cannot be ignored.
[0005] Therefore, how to improve the performance of the excitation system while taking into account economy has become a hot topic in current research. Summary of the invention
[0006] The purpose of the present invention is to provide a hybrid current source excitation device and control method based on semi-controlled and fully controlled devices, which can enhance the system's response capability to faults and emergencies while maintaining high power handling capability and cost advantages, and improve system stability and power quality.
[0007] In order to achieve the above object, the solution of the present invention is:
[0008] A hybrid current source excitation device based on semi-controlled and fully controlled devices, comprising a parallel excitation main converter and a series compensation converter, wherein the parallel excitation main converter comprises a semi-controlled device, the output side of which is connected to the excitation winding of the generator, and is used to indirectly absorb or inject reactive power into the power grid through the generator under the control of a first switch signal; the series compensation converter comprises a fully controlled device, the output side of which is connected to the excitation winding of the generator through a series compensation branch inductance, and is used to directly absorb or inject reactive power into the power grid under the control of a second switch signal; the positive and negative poles of the DC side of the parallel excitation main converter are respectively connected to the positive and negative poles of the series compensation converter.
[0009] It also includes a series compensation bypass switch connected to the output end of the series compensation converter, which is used to control whether the series compensation converter is put into use.
[0010] Wherein, the parallel excitation main converter adopts a three-phase half-controlled rectifier circuit, including a three-phase bridge arm, each phase bridge arm includes two thyristors, recorded as a first thyristor and a second thyristor; wherein, the anode of the first thyristor serves as the first end of the bridge arm, the cathode of the first thyristor is connected to the anode of the second thyristor as the midpoint of the bridge arm, and the cathode of the second thyristor serves as the second end of the bridge arm; the first end of the three-phase bridge arm is connected as the positive electrode of the three-phase half-controlled rectifier circuit, the second end of the three-phase bridge arm is connected as the negative electrode of the three-phase half-controlled rectifier circuit, the midpoint of the three-phase bridge arm serves as the output end, and the gate of each thyristor is used to receive the first switching signal.
[0011] Wherein, the series compensation converter adopts a three-phase fully-controlled rectifier circuit, including a three-phase bridge arm, and each phase bridge arm includes a first fully-controlled device and a second fully-controlled device; the emitter and collector of each fully-controlled device are respectively connected to the positive and negative electrodes of the diode connected in series with it; wherein, the collector of the first fully-controlled device serves as the first end of the bridge arm, the emitter of the first fully-controlled device is connected to the collector of the second fully-controlled device as the midpoint of the bridge arm, and the emitter of the second fully-controlled device serves as the second end of the bridge arm; the first end of the three-phase bridge arm is connected as the positive electrode of the three-phase fully-controlled rectifier circuit, the second end of the three-phase bridge arm is connected as the negative electrode of the three-phase fully-controlled rectifier circuit, the midpoint of the three-phase bridge arm serves as the output end, and the gate of each fully-controlled device is used to receive the second switching signal.
[0012] The parallel excitation main converter is connected in parallel with the generator terminal via the excitation main transformer, and the series compensation converter is connected in series with the generator terminal via the series compensation transformer.
[0013] The control device based on the hybrid current source type excitation device of the semi-controlled and fully controlled devices as mentioned above comprises:
[0014] A parallel excitation control module is configured to control the opening and closing of the semi-controlled device in the parallel excitation main converter by using the first switch signal, so that the parallel excitation main converter absorbs or injects the first reactive power into the power grid; and
[0015] A series compensation control module is configured to control the opening and closing of the fully controlled components in the series compensation converter by using the second switch signal, so that the series compensation converter absorbs or injects the second reactive power into the power grid;
[0016] The sum of the first reactive power and the second reactive power is equal to the reactive power command value.
[0017] The parallel excitation control module is respectively connected to each semi-controlled device in the parallel excitation main converter, and uses the first switch signal to control the opening and closing of each semi-controlled device, thereby adjusting the excitation current of the generator, so that the parallel excitation main converter absorbs or injects the first reactive power into the power grid;
[0018] The series compensation control module is connected to each fully-controlled device in the series compensation converter respectively, and uses the second switch signal to control the opening and closing of each fully-controlled device, thereby adjusting the excitation current of the generator, so that the series compensation converter absorbs or injects the second reactive power into the power grid.
[0019] Wherein, the method for obtaining the first and second switch signals is:
[0020] The reactive power feedback value absorbed or injected into the power grid by the shunt excitation main converter and the series compensation converter is obtained from the generator end, and the first and second switching signals are obtained according to the reactive power feedback value and the reactive power command value, so that the sum of the reactive powers absorbed or injected into the power grid by the shunt excitation main converter under the control of the first switching signal and the series compensation converter under the control of the second switching signal is equal to the reactive power command value.
[0021] Among them, it also includes:
[0022] The series compensation converter input control module is configured to determine whether to input the series compensation converter according to the generator working status signal; wherein, when the generator working status signal is that the generator is operating normally, the connection between the series compensation converter and the generator is disconnected; when the generator working status signal is that the generator fails, the series compensation converter is connected to the generator.
[0023] The control method of the hybrid current source excitation device based on the semi-controlled and fully controlled devices as mentioned above includes:
[0024] Controlling the opening and closing of the semi-controlled device in the parallel excitation main converter by the first switch signal, so that the parallel excitation main converter absorbs or injects the first reactive power into the power grid;
[0025] Using the second switch signal to control the opening and closing of the fully controlled components in the series compensation converter, so that the series compensation converter absorbs or injects the second reactive power into the power grid;
[0026] The sum of the first reactive power and the second reactive power is equal to the reactive power command value.
[0027] The method of controlling the opening and closing of the semi-controlled components in the parallel excitation main converter by the first switching signal includes controlling the opening and closing of each semi-controlled component in the parallel excitation main converter by the first switching signal, thereby adjusting the excitation current of the generator, so that the parallel excitation main converter absorbs or injects the first reactive power into the power grid;
[0028] Using the second switch signal to control the opening and closing of fully-controlled devices in the series compensation converter includes using the second switch signal to control the opening and closing of each fully-controlled device in the series compensation converter, thereby adjusting the excitation current of the generator so that the series compensation converter absorbs or injects a second reactive power into the power grid.
[0029] Wherein, the method for obtaining the first and second switch signals is:
[0030] The reactive power feedback value absorbed or injected into the power grid by the shunt excitation main converter and the series compensation converter is obtained from the generator end, and the first and second switching signals are obtained according to the reactive power feedback value and the reactive power command value, so that the sum of the reactive powers absorbed or injected into the power grid by the shunt excitation main converter under the control of the first switching signal and the series compensation converter under the control of the second switching signal is equal to the reactive power command value.
[0031] Among them, it also includes:
[0032] The generator working status signal is obtained, and whether to put the series compensation converter into operation is determined according to the generator working status signal; wherein, when the generator working status signal indicates that the generator is operating normally, the connection between the series compensation converter and the generator is disconnected; when the generator working status signal indicates that the generator fails, the series compensation converter is connected to the generator.
[0033] A power generation system includes a generator and a main transformer, wherein the generator end is connected to a power grid via the main transformer; and also includes a hybrid current source excitation device based on semi-controlled and fully controlled devices as described above.
[0034] After adopting the above scheme, the present invention can achieve the following beneficial effects:
[0035] (1) In terms of device usage, the advantages of semi-controlled devices and fully-controlled devices are combined. Semi-controlled devices and fully-controlled devices are used to form the parallel excitation main channel and the series compensation channel respectively, which can improve the overall performance of the system and have the advantage of cost-effectiveness while maintaining high power handling capability.
[0036] (2) The present invention adopts a parallel connection of a parallel excitation main channel and a series compensation channel, which can improve the current handling capacity and voltage stability of the system. By controlling the series compensation switch to control the commissioning of the series compensation channel, the system's response capability to sudden conditions such as short circuit faults, open circuit faults and voltage fluctuations can be enhanced.
[0037] (3) The parallel excitation main channel in the present invention adopts semi-controlled devices, which can handle larger currents and higher voltages and are suitable for large-capacity excitation systems; semi-controlled devices (such as thyristors) are mature in technology, simple in structure, highly reliable and low in cost, which enables the system to have better economy while maintaining high power handling capability;
[0038] (4) The present invention introduces a fully controlled device to form a series compensation channel, which can quickly provide reactive power compensation when voltage fluctuations or short circuit faults occur in the system, thereby improving the dynamic response performance and stability of the system. The series compensation channel can also perform impedance compensation, which is beneficial to the reactive power distribution of each unit when the generators are running in parallel.
[0039] (5) In addition to providing stable excitation current support for the generator, it can also provide power guarantee in the event of a machine-side fault, perform additional damping control, and comprehensively improve the reliability and stability of the generator excitation system. BRIEF DESCRIPTION OF THE DRAWINGS
[0040] Figure 1 It is a schematic diagram of a hybrid current source excitation device based on semi-controlled and fully controlled devices provided by an embodiment of the present invention;
[0041] Figure 2 It is a schematic diagram of the topological structure of a hybrid current source excitation device of semi-controlled and fully-controlled devices provided in an embodiment of the present invention. DETAILED DESCRIPTION
[0042] The technical solutions and beneficial effects of the present invention will be described in detail below with reference to the accompanying drawings.
[0043] In order to further improve the performance and economy of the generator excitation system, the present invention provides a hybrid current source excitation device and control method based on semi-controlled and fully controlled devices. The overall idea is: a parallel excitation main channel composed of semi-controlled devices is used to provide the main working current of the excitation winding when the generator is operating normally. When a voltage abnormality occurs, an added series compensation channel is used to obtain energy from the machine-end current to supplement the excitation current to the generator to ensure the normal operation of the excitation system; finally, the parallel excitation main channel and the series compensation channel system cooperate to effectively take into account the performance of the excitation system and the economy of operation.
[0044] The present invention provides a hybrid current source excitation device based on semi-controlled and fully controlled devices, comprising a parallel excitation main converter and a series compensation converter, wherein the parallel excitation main converter comprises a semi-controlled device, the output side of which is connected to the excitation winding of a generator, and is used to indirectly absorb or inject reactive power into a power grid through the generator under the control of a first switch signal; the series compensation converter comprises a fully controlled device, the output side of which is connected to the excitation winding of the generator through a series compensation branch inductance, and is used to directly absorb or inject reactive power into the power grid under the control of a second switch signal; the positive and negative poles of the DC side of the parallel excitation main converter are respectively connected to the positive and negative poles of the series compensation converter.
[0045] Embodiment 1:
[0046] The embodiment of the present invention provides a hybrid current source excitation device based on semi-controlled and fully controlled devices, such as Figure 1 As shown, it includes two circuits connected in parallel: a parallel excitation main converter composed of half-controlled devices, whose output side is connected to the excitation winding of the generator, and is used to adjust the excitation current of the generator, and indirectly absorb or inject reactive power into the power grid through the generator; a series compensation converter composed of full-controlled devices, whose output end is connected to the excitation winding of the generator through the series compensation branch inductance, and is used to adjust the excitation current of the generator. In addition to indirectly absorbing or injecting reactive power into the power grid through the generator, it can also directly perform reactive power compensation through the AC side. In addition, it can also play the role of compensating impedance and distributing current to the parallel excitation main converter and the series compensation converter, which is beneficial to the reactive power distribution of each unit when the generator is running.
[0047] As a preferred embodiment, Figure 2 As shown, in this embodiment, the semi-controlled and fully-controlled hybrid current source excitation device also includes:
[0048] The series compensation bypass switch is used in conjunction with the series compensation converter to control whether the series compensation converter is put into use.
[0049] The power generation system provided by the present invention adopts semi-controlled devices and fully-controlled devices to respectively form a parallel excitation main channel and a series compensation channel, with two excitation channels in total, both of which can be used to provide excitation current to the generator. In addition, the series compensation channel can also play the role of compensating impedance, distributing current between the two channels, and directly providing reactive power support to the power grid.
[0050] Specifically, since the response speed of the fully controlled device is faster than that of the semi-controlled device, the AC side of the series compensation channel can absorb or inject reactive power into the power grid more quickly than the parallel excitation main channel, and quickly provide reactive support to the power grid. When the generator is operating normally, the parallel excitation main channel provides the main working current of the excitation winding; when the generator end fails, the series compensation channel provides power guarantee, assists the parallel excitation main channel to provide stable excitation current support for the generator, and performs additional damping control, which comprehensively improves the reliability and stability of the generator excitation system.
[0051] like Figure 2 As shown, in this embodiment, the parallel excitation main converter adopts a three-phase half-controlled rectifier circuit structure, including three-phase bridge arms, each phase bridge arm includes two thyristors, which are recorded as the first thyristor and the second thyristor;
[0052] The anode of the first thyristor serves as the first end of the bridge arm, the cathode of the first thyristor is connected to the anode of the second thyristor as the midpoint of the bridge arm, and the cathode of the second thyristor serves as the second end of the bridge arm; in the three-phase half-controlled rectifier circuit, the first end of the three-phase bridge arm is connected as the positive electrode of the three-phase half-controlled rectifier circuit, the second end of the three-phase bridge arm is connected as the negative electrode of the three-phase half-controlled rectifier circuit, the midpoint of the three-phase bridge arm serves as the output end, and the gate of each thyristor is connected to the control device; Figure 2 As shown, the three-phase half-controlled rectifier circuit includes 6 thyristors, which are T1 to T6 in sequence. The anodes of T1, T3, and T5 are respectively used as the first ends of the bridge arms, and the cathodes of T2, T4, and T6 are respectively used as the second ends of the bridge arms. The cathodes of T1, T3, and T5 are respectively connected to the anodes of T2, T4, and T6.
[0053] The series compensation converter adopts the structure of a three-phase fully controlled rectifier circuit, and also includes three-phase bridge arms, each phase bridge arm includes two unidirectional conduction fully controlled devices (wherein the fully controlled devices can be IGBTs, GTOs, etc.), which are recorded as the first fully controlled device and the second fully controlled device; the emitter and collector of each fully controlled device are respectively connected to the positive and negative electrodes of the diode connected in series with it;
[0054] The collector of the first fully-controlled device serves as the first end of the bridge arm, the emitter of the first fully-controlled device is connected to the collector of the second fully-controlled device as the midpoint of the bridge arm, and the emitter of the second fully-controlled device serves as the second end of the bridge arm; in the three-phase fully-controlled rectifier circuit, the first end of the three-phase bridge arm is connected as the positive electrode of the three-phase fully-controlled rectifier circuit, the second end of the three-phase bridge arm is connected as the negative electrode of the three-phase fully-controlled rectifier circuit, the midpoint of the three-phase bridge arm serves as the output end, and the gate of each fully-controlled device is connected to the control device; Figure 2 As shown, the three-phase rectifier circuit includes 6 unidirectional conduction fully controlled devices, namely S1 to S6, the collectors of S1, S3, and S5 are respectively used as the first ends of the bridge arms, the emitters of S2, S4, and S6 are respectively used as the second ends of the bridge arms, and the emitters of S1, S3, and S5 are respectively connected to the collectors of S2, S4, and S6;
[0055] The positive and negative poles of the DC side of the parallel excitation main converter are connected to the positive and negative poles of the series compensation converter respectively.
[0056] like Figure 1 and Figure 2 As shown, in this embodiment, the parallel excitation main converter is specifically connected in parallel with the generator end through an excitation main transformer, and the series compensation converter is specifically connected in series with the generator end through a series compensation transformer connected in parallel with the series compensation bypass switch. The series compensation bypass switch includes two parallel thyristors, denoted as a third thyristor and a fourth thyristor, the anode of the third thyristor is connected to the cathode of the fourth thyristor, and the cathode of the third thyristor is connected to the anode of the fourth thyristor.
[0057] The series compensation bypass switch is used in conjunction with the series compensation channel of the excitation device. When the parallel excitation main channel works normally, an enable signal is sent to close the series compensation bypass switch, the stator current of the generator flows through the parallel excitation main channel, and the series compensation channel exits operation; when the series compensation channel needs to work, the enable signal of the series compensation bypass switch is canceled, and the series compensation channel works.
[0058] The series compensation branch inductance is used to control the current distribution between the two converters.
[0059] The present invention utilizes a series compensation channel to provide the generator with a stable excitation current during normal operation and excitation current support during sudden faults, thereby ensuring economy and improving the operating stability of the power generation system.
[0060] like Figure 1 and Figure 2As shown, in this embodiment, in the hybrid current source excitation device based on semi-controlled and fully controlled devices, all devices in the parallel excitation main converter control circuit are thyristors, which have a simple structure, high reliability and low cost, and can handle larger currents and higher voltages. All devices in the series compensation converter control circuit are fully controlled devices (which can be IGBT, GTO, etc.), and their control is more flexible and controllable.
[0061] This embodiment can provide excitation current to the generator via the parallel excitation main channel and the series compensation channel; when the power system operates normally, the parallel excitation main channel provides the main or all excitation current to the generator, and the series compensation channel provides the compensation excitation current; when a fault occurs in the power system, the series compensation bypass switch enable signal is canceled, and the parallel excitation main channel and the series compensation channel simultaneously provide excitation current to the generator to prevent the excitation capacity of the generator from decreasing due to the reduction of the excitation current, which can greatly reduce the impact of the AC system fault; in addition, in addition to compensating for reactive power, the series compensation channel can also compensate for impedance to improve the reliability of the power generation system.
[0062] This embodiment can absorb or inject reactive power to the power grid indirectly and directly through the parallel excitation main channel and the series compensation channel. Due to the fast response speed of the fully controlled device, the AC side of the series compensation channel can directly and quickly absorb or inject active power and reactive power to the power grid to provide reactive power support for the power grid. The two channels work together to enhance the system's response to emergencies such as short circuit faults, open circuit faults, and voltage fluctuations while maintaining high power handling capabilities and cost advantages.
[0063] like Figure 1 As shown, through the series compensation channel, current compensation can be performed on the generator end, and the compensation current is Δi s , through current compensation, reactive power Q can be absorbed or injected into the grid cp This embodiment can accurately compensate the machine-end voltage through the series compensation channel, provide power guarantee when the machine-end fails, prevent the impact of voltage fluctuations on the load, and comprehensively improve the reliability and stability of the generator excitation system.
[0064] The present invention also discloses a control device based on the aforementioned hybrid current source excitation device of semi-controlled and fully controlled devices, comprising:
[0065] A parallel excitation control module is configured to control the opening and closing of the semi-controlled device in the parallel excitation main converter by using the first switch signal, so that the parallel excitation main converter absorbs or injects the first reactive power into the power grid; and
[0066] A series compensation control module is configured to control the opening and closing of the fully controlled components in the series compensation converter by using the second switch signal, so that the series compensation converter absorbs or injects the second reactive power into the power grid;
[0067] The sum of the first reactive power and the second reactive power is equal to the reactive power command value.
[0068] Embodiment 2:
[0069] The control device is connected to each half-controlled device and full-controlled device in the parallel excitation main converter and the series compensation converter respectively, and is used to generate a switching signal according to the reactive power command value absorbed or injected into the power grid by the hybrid current source type excitation device based on the half-controlled and full-controlled devices and the corresponding feedback value, so as to control the opening and closing of each half-controlled device and full-controlled device in the hybrid current source type excitation device based on the half-controlled and full-controlled devices, so that the reactive power absorbed or injected into the power grid by the power generation system is equal to the command value.
[0070] In this embodiment, the control device specifically includes: a parallel excitation control module and a series compensation control module;
[0071] The parallel excitation control module is connected to each semi-controlled device in the parallel excitation main converter respectively. According to the input signal of the detected voltage, current or other state quantity of the generator, the output of the excitation power unit is automatically adjusted according to the given excitation control criteria, that is, by controlling the conduction angle of the thyristor in the parallel excitation main converter to adjust the excitation current of the synchronous generator, the voltage regulation and reactive power distribution of the synchronous generator and other control functions are realized.
[0072] The series compensation control module is connected to each fully-controlled device in the series compensation circuit, and provides control signals for the series compensation converter. The series compensation control module obtains control instructions such as excitation and reactive power based on the collected parameters such as machine-end voltage, reactive power, and unit speed. The switching signal for controlling the converter is obtained based on the instruction value and the collected excitation and reactive feedback values to control the opening and closing of the fully-controlled devices in the series compensation circuit, thereby realizing the excitation current compensation and fast reactive power support functions.
[0073] In practical applications, the reactive power command value can be optimized and solved according to the grid structure, parameters, current operating conditions and feedback signals of each module, with the goal of minimizing grid losses and maximizing voltage quality.
[0074] The present invention provides a control method for the aforementioned hybrid current source excitation device based on semi-controlled and fully controlled devices, comprising:
[0075] Controlling the opening and closing of the semi-controlled device in the parallel excitation main converter by the first switch signal, so that the parallel excitation main converter absorbs or injects the first reactive power into the power grid;
[0076] Using the second switch signal to control the opening and closing of the fully controlled components in the series compensation converter, so that the series compensation converter absorbs or injects the second reactive power into the power grid;
[0077] The sum of the first reactive power and the second reactive power is equal to the reactive power command value.
[0078] Embodiment 3:
[0079] The control method of the hybrid current source excitation device based on semi-controlled and fully-controlled devices provided in the above-mentioned embodiment 1 includes:
[0080] In normal operation, the reactive power absorbed or injected into the grid is only indirectly through the parallel excitation main channel, and the switching signal of the semi-controlled device is obtained according to the reactive power command value;
[0081] When a fault occurs, the parallel excitation main channel and the series compensation channel absorb or inject reactive power into the grid indirectly and directly respectively. The total reactive power value is equal to the reactive power feedback value. The series compensation simultaneously compensates for the impedance and distributes the reactive power to the two channels, thereby obtaining the switching signals of the semi-controlled devices and the fully-controlled devices respectively. The sum of the reactive power absorbed or injected into the grid by the two channels is equal to the reactive power command value.
[0082] Among them, the way to obtain each instruction value is:
[0083] A reactive power feedback value indirectly absorbed or injected into the power grid through a parallel excitation main channel by a hybrid current source excitation device based on semi-controlled or fully-controlled devices is obtained from the generator end, and a switching signal is obtained according to the reactive power feedback value and the reactive power command value. The reactive power indirectly absorbed or injected into the power grid through a parallel excitation main channel by a hybrid current source excitation device based on semi-controlled or fully-controlled devices is equal to the reactive power command value through the control of the excitation current.
[0084] A reactive power feedback value absorbed or injected into the power grid through a series compensation channel by a hybrid current source excitation device based on semi-controlled or fully-controlled devices is obtained from the generator end, and a switching signal is obtained according to the reactive power feedback value and the reactive power command value. The reactive power absorbed or injected into the power grid through the series compensation channel by the hybrid current source excitation device based on semi-controlled or fully-controlled devices is made equal to the reactive power command value by controlling the excitation current and the AC side current.
[0085] Similarly, in this embodiment, the reactive power command value can be optimized and solved according to the grid structure, parameters, current operating conditions and feedback signals of each module, with the goal of minimizing grid loss and maximizing voltage quality.
[0086] The present invention also provides a power generation system, such as Figure 1 As shown, it includes a generator and a main transformer, and the generator end is connected to the power grid via the main transformer; it is characterized by: it also includes a hybrid current source excitation device based on semi-controlled and fully controlled devices as described above.
[0087] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The schemes in the embodiments of the present invention may be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.
[0088] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.
[0089] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.
[0090] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.
[0091] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.
[0092] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.
Claims
1. A hybrid current source excitation device based on semi-controlled and fully controlled devices, characterized in that: It includes a parallel excitation main converter and a series compensation converter, wherein the parallel excitation main converter includes a semi-controlled device, the output side of which is connected to the excitation winding of the generator, and is used to indirectly absorb or inject reactive power into the power grid through the generator under the control of a first switch signal; the series compensation converter includes a fully controlled device, the output side of which is connected to the excitation winding of the generator through a series compensation branch inductance, and is used to directly absorb or inject reactive power into the power grid under the control of a second switch signal; the positive and negative poles of the DC side of the parallel excitation main converter are respectively connected to the positive and negative poles of the series compensation converter.
2. The device according to claim 1, characterized in that: It also includes a series compensation bypass switch connected to the output end of the series compensation converter, which is used to control whether the series compensation converter is put into use.
3. The device according to claim 1, characterized in that: The parallel excitation main converter adopts a three-phase half-controlled rectifier circuit, including a three-phase bridge arm, each phase bridge arm includes two thyristors, which are recorded as a first thyristor and a second thyristor; wherein, the anode of the first thyristor serves as the first end of the bridge arm, the cathode of the first thyristor is connected to the anode of the second thyristor as the midpoint of the bridge arm, and the cathode of the second thyristor serves as the second end of the bridge arm; the first end of the three-phase bridge arm is connected as the positive electrode of the three-phase half-controlled rectifier circuit, the second end of the three-phase bridge arm is connected as the negative electrode of the three-phase half-controlled rectifier circuit, the midpoint of the three-phase bridge arm serves as the output end, and the gate of each thyristor is used to receive a first switching signal.
4. The device according to claim 1, characterized in that: The series compensation converter adopts a three-phase fully-controlled rectifier circuit, including three-phase bridge arms, each phase bridge arm includes a first fully-controlled device and a second fully-controlled device; the emitter and collector of each fully-controlled device are respectively connected to the positive and negative electrodes of the diode connected in series with it; wherein, the collector of the first fully-controlled device serves as the first end of the bridge arm, the emitter of the first fully-controlled device is connected to the collector of the second fully-controlled device as the midpoint of the bridge arm, and the emitter of the second fully-controlled device serves as the second end of the bridge arm; the first end of the three-phase bridge arm is connected as the positive electrode of the three-phase fully-controlled rectifier circuit, the second end of the three-phase bridge arm is connected as the negative electrode of the three-phase fully-controlled rectifier circuit, the midpoint of the three-phase bridge arm serves as the output end, and the gate of each fully-controlled device is used to receive the second switching signal.
5. The device according to claim 1, characterized in that: The parallel excitation main converter is connected in parallel with the machine end of the generator through the excitation main transformer, and the series compensation converter is connected in series with the machine end of the generator through the series compensation transformer.
6. The control device based on the hybrid current source type excitation device of half-controlled and full-controlled devices as claimed in claim 1, characterized in that: include, A parallel excitation control module is configured to control the opening and closing of the semi-controlled device in the parallel excitation main converter by using the first switch signal, so that the parallel excitation main converter absorbs or injects the first reactive power into the power grid; and A series compensation control module is configured to control the opening and closing of the fully controlled components in the series compensation converter by using the second switch signal, so that the series compensation converter absorbs or injects the second reactive power into the power grid; The sum of the first reactive power and the second reactive power is equal to the reactive power command value.
7. The control device according to claim 6, characterized in that: The parallel excitation control module is connected to each semi-controlled device in the parallel excitation main converter, and uses the first switch signal to control the opening and closing of each semi-controlled device, thereby adjusting the excitation current of the generator, so that the parallel excitation main converter absorbs or injects the first reactive power into the power grid; The series compensation control module is connected to each fully-controlled device in the series compensation converter respectively, and uses the second switch signal to control the opening and closing of each fully-controlled device, thereby adjusting the excitation current of the generator, so that the series compensation converter absorbs or injects the second reactive power into the power grid.
8. The control device according to claim 6, characterized in that: The method for obtaining the first and second switch signals is: The reactive power feedback value absorbed or injected into the power grid by the shunt excitation main converter and the series compensation converter is obtained from the generator end, and the first and second switching signals are obtained according to the reactive power feedback value and the reactive power command value, so that the sum of the reactive powers absorbed or injected into the power grid by the shunt excitation main converter under the control of the first switching signal and the series compensation converter under the control of the second switching signal is equal to the reactive power command value.
9. The control device according to claim 6, characterized in that: Also includes, The series compensation converter input control module is configured to determine whether to input the series compensation converter according to the generator working status signal; wherein, when the generator working status signal is that the generator is operating normally, the connection between the series compensation converter and the generator is disconnected; when the generator working status signal is that the generator fails, the series compensation converter is connected to the generator.
10. The control method of the hybrid current source excitation device based on half-controlled and full-controlled devices according to claim 1, characterized in that: include, Controlling the opening and closing of the semi-controlled device in the parallel excitation main converter by the first switch signal, so that the parallel excitation main converter absorbs or injects the first reactive power into the power grid; Using the second switch signal to control the opening and closing of the fully controlled components in the series compensation converter, so that the series compensation converter absorbs or injects the second reactive power into the power grid; The sum of the first reactive power and the second reactive power is equal to the reactive power command value.
11. The control method according to claim 10, characterized in that: Controlling the disconnection of the semi-controlled components in the parallel excitation main converter with the first switch signal, including controlling the disconnection of each semi-controlled component in the parallel excitation main converter with the first switch signal, thereby adjusting the excitation current of the generator, so that the parallel excitation main converter absorbs or injects the first reactive power into the power grid; Using the second switch signal to control the opening and closing of fully-controlled devices in the series compensation converter includes using the second switch signal to control the opening and closing of each fully-controlled device in the series compensation converter, thereby adjusting the excitation current of the generator so that the series compensation converter absorbs or injects a second reactive power into the power grid.
12. The control method according to claim 10, characterized in that: The method for obtaining the first and second switch signals is: The reactive power feedback value absorbed or injected into the power grid by the shunt excitation main converter and the series compensation converter is obtained from the generator end, and the first and second switching signals are obtained according to the reactive power feedback value and the reactive power command value, so that the sum of the reactive powers absorbed or injected into the power grid by the shunt excitation main converter under the control of the first switching signal and the series compensation converter under the control of the second switching signal is equal to the reactive power command value.
13. The control method according to claim 10, characterized in that: Also includes, The generator working status signal is obtained, and whether to put the series compensation converter into operation is determined according to the generator working status signal; wherein, when the generator working status signal indicates that the generator is operating normally, the connection between the series compensation converter and the generator is disconnected; when the generator working status signal indicates that the generator fails, the series compensation converter is connected to the generator.
14. A power generation system, comprising a generator and a main transformer, wherein the generator terminal is connected to a power grid via the main transformer; characterized in that: It also includes a hybrid current source excitation device based on semi-controlled and fully controlled devices as described in any one of claims 1 to 5.