Direct-current system starting control method, direct-current system, and storage medium

Abstract

The application provides a starting control method of a direct current system, a direct current system and a storage medium. The method comprises the following steps: controlling a first switch and a second switch to be turned off to control a sending end charging resistor and a receiving end charging resistor to be connected to the direct current system when sending end converter valves and receiving end converter valves are in a blocking state; controlling the sending end and the receiving end to be powered on and performing the step of starting first support valves and second support valves after a starting signal is activated; controlling the first switch and the second switch to be turned on to control the sending end charging resistor and the receiving end charging resistor not to be connected to the direct current system and to unlock first main valves and second main valves after the starting of the first support valves and the second support valves is completed, and then starting the first main valves by using direct current and starting the second main valves by using direct current voltage. The problem that there is no starting scheme for the direct current system based on the full-control composite converter which takes into account the accurate power transmission and the smooth power transition in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of direct current transmission, in particular to a starting control method of a direct current system, a direct current system and a storage medium. BACKGROUND

[0002] As the core component of the direct current transmission system, the performance of the ultra-high voltage direct current converter directly affects the efficiency and reliability of power transmission. However, with the increasing proportion of new energy in the power grid, the phenomenon of "hollowing" of the power grid gradually appears, which leads to the decline of the dynamic reactive power regulation capability of the power grid, the risk of commutation failure of the conventional direct current converter under small disturbance is increased, and the stable operation of the power grid is seriously threatened.

[0003] The full-control composite converter connects the three-phase multi-bridge arm structure IGCT straight string valve (i.e. the main valve) and the three-phase full-bridge module (i.e. the support valve) in parallel at the AC side, and forms a composite converter with voltage source and current source characteristics. The main valve composed of high-voltage and high-power IGCT devices realizes large-capacity active power transmission, and the voltage source support valve with flexible and controllable output voltage realizes the reactive power support capability of the converter to the power grid. There is a lack of a starting scheme for the direct current system based on the full-control composite converter, which takes into account the accurate power transmission and smooth power transition. SUMMARY

[0004] The main purpose of the present application is to provide a starting control method of a direct current system, a direct current system and a storage medium, so as to solve the problem that there is a lack of a starting scheme for the direct current system based on the full-control composite converter, which takes into account the accurate power transmission and smooth power transition.

[0005] In order to achieve the above object, according to one aspect of the present application, a starting control method of a DC system is provided, the DC system comprising a sending end and a receiving end, the sending end comprising a sending end converter valve, a sending end charging resistor and a first switch connected in parallel with the sending end charging resistor, the receiving end comprising a receiving end converter valve, a receiving end charging resistor and a second switch connected in parallel with the receiving end charging resistor, the sending end converter valve comprising a first main valve and a first support valve, the receiving end converter valve comprising a second main valve and a second support valve, the first main valve and the second main valve being IGCT straight string valves, the first support valve and the second support valve comprising full-bridge modules, the starting control method comprising: controlling the sending end charging resistor and the receiving end charging resistor to be connected to the DC system by turning off the first switch and the second switch when the sending end converter valve and the receiving end converter valve are in a blocking state; after a starting signal is activated, controlling the sending end and the receiving end to be powered on, and performing a step of starting the first support valve and the second support valve, the starting signal being activated representing that a starting process is entered; after the first support valve and the second support valve are started, controlling the first switch and the second switch to be turned on to control the sending end charging resistor and the receiving end charging resistor not to be connected to the DC system and to unlock the first main valve and the second main valve, and then controlling the first main valve to be started by using a DC current and controlling the second main valve to be started by using a DC voltage.

[0006] Optionally, the step of controlling the first main valve to be started by using a DC current and controlling the second main valve to be started by using a DC voltage comprises: controlling the first main valve to be started by using an increasing DC current, the increasing rate of the DC current being a DC current increasing rate; and controlling the second main valve to be started by using an increasing DC voltage, the increasing rate of the DC voltage being a DC voltage increasing rate, the dimensionless quantity of the DC voltage increasing rate being less than the dimensionless quantity of the DC current increasing rate.

[0007] Optionally, the method further comprises: obtaining an IGCT characteristic parameter of the first main valve and an IGCT characteristic parameter of the second main valve, wherein the IGCT characteristic parameter comprises a current characteristic of the IGCT; and determining a DC current increasing rate and a DC voltage increasing rate according to at least the IGCT characteristic parameter of the first main valve and the IGCT characteristic parameter of the second main valve, the DC current increasing rate being an increasing rate of a DC current used for controlling the first main valve to be started, and the DC voltage increasing rate being an increasing rate of a DC voltage used for controlling the second main valve to be started.

[0008] Optionally, determining the DC current rise rate and the DC voltage rise rate according to the IGCT characteristic parameter of the first main valve and the IGCT characteristic parameter of the second main valve comprises: obtaining a main protection mechanism of the DC system, wherein the main protection mechanism is adapted to a start-up rate of the DC system, and triggering the main protection control if the DC current rise rate is greater than a preset current rise rate and / or the DC voltage rise rate is greater than a preset voltage rise rate; determining the DC current rise rate and the DC voltage rise rate according to the IGCT characteristic parameter of the first main valve, the IGCT characteristic parameter of the second main valve and the main protection mechanism.

[0009] Optionally, determining the DC current rise rate and the DC voltage rise rate according to the IGCT characteristic parameter of the first main valve and the IGCT characteristic parameter of the second main valve comprises: determining an upper limit of a current change rate tolerance of the IGCT in the first main valve according to the IGCT characteristic parameter of the first main valve, and determining an upper limit of a current change rate tolerance of the IGCT in the second main valve according to the IGCT characteristic parameter of the second main valve; determining the DC current rise rate and the DC voltage rise rate based on a constraint condition, the constraint condition comprising: a current change rate applied to the IGCT in the first main valve during the start-up process being lower than the upper limit of the current change rate tolerance of the IGCT in the first main valve, a current change rate applied to the IGCT in the second main valve during the start-up process being lower than the upper limit of the current change rate tolerance of the IGCT in the second main valve, and the main protection mechanism not being triggered.

[0010] Optionally, determining the DC current rise rate and the DC voltage rise rate according to the IGCT characteristic parameter of the first main valve and the IGCT characteristic parameter of the second main valve comprises: constructing a preset mapping relationship, the preset mapping relationship representing a relationship between cause variables and result variables, the cause variables comprising the IGCT characteristic parameter of the first main valve, the IGCT characteristic parameter of the second main valve and the main protection mechanism, and the result variables comprising the DC current rise rate and the DC voltage rise rate; determining a current result variable according to the preset mapping relationship and a current cause variable, the current cause variable comprising a current IGCT characteristic parameter of the first main valve, a current IGCT characteristic parameter of the second main valve and a current main protection mechanism, and the current result variable comprising a current DC current rise rate and a current DC voltage rise rate.

[0011] Optionally, the step of starting the first support valve and the second support valve comprises: unlocking the first support valve and the second support valve when a direct current voltage of the first support valve and the second support valve is charged to a preset voltage; continuing to charge the first support valve and the second support valve until the direct current voltage of the first support valve and the second support valve is charged to a rated voltage, determining that the starting of the first support valve and the second support valve is completed, and the preset voltage is less than the rated voltage.

[0012] Optionally, the step of controlling the first main valve by a direct current to start the first main valve and controlling the second main valve by a direct voltage to start the second main valve comprises: controlling the first main valve by a first PI control loop based on the direct current to start the first main valve; and controlling the second main valve by a second PI control loop based on the direct voltage to start the second main valve.

[0013] According to still another aspect of the present application, a direct current system is provided, comprising: a sending end and a receiving end, the sending end comprising a sending end converter valve, a sending end charging resistor and a transformer set, the receiving end comprising a receiving end converter valve and a receiving end charging resistor and a transformer set, the sending end converter valve comprising a first main valve and a first support valve, the receiving end converter valve comprising a second main valve and a second support valve, the first main valve and the second main valve being IGCT straight string valves and the IGCT straight string valves being three-phase twelve-bridge-arm IGCT straight string valves, the first support valve and the second support valve being two groups of three-phase full-bridge modules, and any of the transformer sets comprising two star-delta connected transformers; and a controller connected with the sending end and the receiving end respectively and used for performing any of the starting control methods of the direct current system.

[0014] According to still another aspect of the present application, a computer readable storage medium is provided, comprising a stored program, wherein the computer readable storage medium performs any of the starting control methods of the direct current system when the program runs.

[0015] The technical solution of the present application can realize the safe and non-impact starting of the F3C converter and the direct current transmission system formed by the F3C converter, ensure the smooth and controllable starting process, improve the operation efficiency and reliability of the system, optimize the reactive power management, and reduce the system cost, and is a high-efficiency and practical starting control strategy. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the application, and are incorporated in and constitute a part of this specification, the illustrative embodiments of the application, and explanations of the same, do not limit the application. In the drawings:

[0017] Figure 1 A flow chart of a start-up control method of a DC system according to an embodiment of the present application is shown;

[0018] Figure 2 A first DC system according to an embodiment of the present application is shown;

[0019] Figure 3 A single-ended converter valve start-up control principle diagram of a DC system according to an embodiment of the present application is shown;

[0020] Figure 4 A second DC system according to an embodiment of the present application is shown;

[0021] Figure 5 A flow chart of a start-up control method of a specific DC system according to an embodiment of the present application is shown;

[0022] Figure 6 A start-up characteristic diagram of a start-up control method of a DC system according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0023] It should be noted that the following detailed description is merely exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0024] It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0025] It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements can also be present. In addition, it will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements can also be present.

[0026] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. It can be understood that "at least one" means one or more, and "multiple" means two or more than two. "At least part of the element" means part or all of the element.

[0027] It can be understood that "connection" in the following embodiments means "electrical connection", "communication connection", etc. if the connected circuits, modules, units, etc. have transmission of electrical signals or data between each other.

[0028] In the description of the embodiments of the present application, the term "and / or" is only used to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can mean that A exists, A and B exist, and B exists. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0029] The terms used in the description of various embodiments herein are only used to describe specific embodiments, and are not intended to be limiting. As used in the description of various embodiments and the appended claims, "part" is also intended to include the plural form, unless the context clearly indicates otherwise.

[0030] The embodiments of the present application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art can understand that in the embodiments of the present application, many technical details are proposed in order to make the reader better understand the present application. However, the technical solutions claimed by the present application can be realized even without these technical details and various changes and modifications based on the following embodiments.

[0031] As introduced in the background, the prior art lacks a starting scheme for a full-control composite converter-based DC system that takes into account accurate power transmission and smooth power transition. In order to solve the problem that the prior art lacks a starting scheme for a full-control composite converter-based DC system that takes into account accurate power transmission and smooth power transition, the present application proposes a DC system starting control method, a DC system and a storage medium.

[0032] The starting control method of the direct current system of the present application is applied to a full-control composite converter direct current system, the full-control composite converter direct current system comprises a sending end and a receiving end, the sending end comprises a sending end converter valve, a sending end charging resistor and a first switch connected in parallel with the sending end charging resistor, the receiving end comprises a receiving end converter valve, a receiving end charging resistor and a second switch connected in parallel with the receiving end charging resistor, the sending end converter valve comprises a first main valve and a first support valve, the receiving end converter valve comprises a second main valve and a second support valve, the first main valve and the second main valve are IGCT straight string valves, and the first support valve and the second support valve comprise full-bridge modules, see Figure 1 The starting control method of the direct current system comprises the following steps:

[0033] In step S101, the first switch and the second switch are controlled to be turned off to control the sending end charging resistor and the receiving end charging resistor to be connected to the direct current system when the sending end converter valve and the receiving end converter valve are in a blocking state.

[0034] Since the first switch is connected in parallel with the sending end charging resistor, when the first switch is turned off, the sending end charging resistor is in a non-short-circuit state, i.e., is connected to the direct current system.

[0035] Since the second switch is connected in parallel with the receiving end charging resistor, when the second switch is turned off, the receiving end charging resistor is in a non-short-circuit state, i.e., is connected to the direct current system.

[0036] Before the starting process starts, it is ensured that the sending end converter valve and the receiving end converter valve are in a blocking state, which can avoid accidental current or voltage surges due to misoperation in the system preparation stage and protect system equipment from damage.

[0037] In step S102, after a starting signal is activated, the sending end and the receiving end are powered on, and a step of starting the first support valve and the second support valve is performed, and the activation of the starting signal indicates that the starting process is entered.

[0038] Specifically, see Figure 2 The full-bridge module comprises an IGBT device, a diode and a capacitor connected in series, and in the initial stage of power-on, the support valve (including the first support valve and the second support valve) will undergo two stages, namely, an uncontrolled charging stage and a controllable charging stage. In the uncontrolled charging stage, no control signal is applied to allow the grid voltage to charge the capacitor in the full-bridge module through the diode. When the capacitor in the full-bridge module is charged to a preset proportion of the rated value (for example, 70% of the rated value), the controllable charging is switched on to charge the IGBT device in the full-bridge module to the rated value.

[0039] The charging resistor is already put into use in the uncontrolled charging stage, which aims to limit the charging current and avoid generating an excessive impact current in the capacitor charging process, thereby causing potential damage to the internal devices of the converter. When the controllable charging is switched on and the capacitor voltage reaches the rated value, the charging resistor is removed.

[0040] Step S103, after the first support valve and the second support valve are started, the first switch and the second switch are closed to control the sending end charging resistor and the receiving end charging resistor not to be connected to the DC system, and the first main valve and the second main valve are unlocked, and then the first main valve is started by using the DC current and the second main valve is started by using the DC voltage.

[0041] Since the first switch is connected in parallel with the sending end charging resistor, when the first switch is closed, the sending end charging resistor is in a short-circuit state, i.e., not connected to the DC system.

[0042] Since the second switch is connected in parallel with the receiving end charging resistor, when the second switch is closed, the receiving end charging resistor is in a short-circuit state, i.e., not connected to the DC system.

[0043] In the field, the converter including the main valve (IGCT straight string valve) and the support valve (including full-bridge module) is also called F3C converter.

[0044] After the support valve is started and reaches a steady state, the charging resistor is cut off (i.e., the charging resistor is controlled to be short-circuited), and the main valve is unlocked, realizing the coordinated start of the support valve to the main valve. At this time, the sending end is controlled by a constant DC current, and the receiving end is controlled by a constant DC voltage, ensuring that the system power smoothly transitions from zero to the rated value, avoiding voltage and current surges during the start-up process, and ensuring the smooth start of the entire DC power transmission system.

[0045] Through the step-by-step start-up strategy of first starting the support valve and then unlocking the main valve, it is ensured that the power devices (such as IGCT) will not bear voltage or current exceeding the design range during the start-up process, thereby prolonging the service life of the equipment and improving the reliability of the system.

[0046] The DC current control of the sending end and the DC voltage control of the receiving end work together during the start-up process, which can accurately control the active power transmission of the system, while ensuring that the system operates in a stable and efficient state, avoiding unnecessary power fluctuations.

[0047] Under the coordinated control of the support valve and the main valve, the converter (equivalent to the converter valve) can operate at a unit power factor with the DC system, i.e., the converter does not exchange reactive power with the DC system. Without additional reactive power compensation equipment, the land area of the converter station is greatly reduced, and the structure of the DC system is simplified.

[0048] With reference to the above analysis, the starting control method of the direct current system comprising steps S101, S102 and S103 can realize safe and non-impact starting of the F3C converter and the direct current transmission system constituted thereby, ensures smooth and controllable starting process, improves system operation efficiency and reliability, optimizes reactive power management, reduces system cost, and is a high-efficiency and practical starting control strategy. The problem of lack of a starting scheme for the direct current system based on the full-control composite converter that takes into account accurate power transmission and smooth power transition in the prior art is solved.

[0049] In a specific implementation, the first main valve is started by using direct current control and the second main valve is started by using direct voltage control, comprising:

[0050] The first main valve is started by using incremental direct current control, and the rising rate of the direct current is a direct current rising rate.

[0051] The second main valve is started by using incremental direct voltage control, and the rising rate of the direct voltage is a direct voltage rising rate, and the dimensionless quantity of the direct voltage rising rate is less than the dimensionless quantity of the direct current rising rate.

[0052] The dimensionless quantity of the direct voltage rising rate refers to the pure numerical quantity of the direct voltage rising rate, and the dimensionless quantity of the direct current rising rate refers to the pure numerical quantity of the direct current rising rate.

[0053] The direct voltage rising rate is set to be less than the direct current rising rate, which is to ensure that the direct voltage of the sending end is always greater than the direct voltage of the receiving end during the starting process. It ensures that the power flows in the positive direction in the direct current system, i.e., the power is transmitted from the sending end to the receiving end, thereby avoiding reverse power flow that may occur at the initial stage of system starting and ensuring positive controllability of system power.

[0054] By controlling the incremental rates of the direct current and the direct voltage, smooth transition of the system from zero power to rated power can be realized. This control method avoids instantaneous power mutation during the starting process, reduces the impact on power devices and insulation elements in the system, and ensures the safety and reliability of the starting process.

[0055] In addition, the incremental control strategy can gradually increase system load, avoiding over-stress on equipment caused by high power demand at the starting moment. For power devices in the high-voltage direct current transmission system, this control method can reduce thermal stress and mechanical stress, prolong the service life of the equipment, and reduce maintenance costs.

[0056] In addition, the increasing rates of the direct current and the direct voltage can be precisely set and monitored, which makes the system state in the starting process can be tracked and adjusted in real time. If the system state deviates from the set value, it can be corrected by adjusting the slope or triggering angle and other parameters, thereby ensuring the controllability and stability of the starting process.

[0057] By setting a reasonable slope, the speed of the system from starting to steady-state operation can be as fast as possible under the premise of safety, reducing the starting time, which means that the power system can respond to power demand changes faster, improving the responsiveness and flexibility of the system.

[0058] Therefore, by using this control strategy, not only can the system be started smoothly, but also the performance can be optimized during system operation, such as improving power transmission efficiency, reducing loss, and maintaining good power quality.

[0059] Based on the above analysis, the direct current control and direct voltage control strategy with increasing rate can effectively ensure the power flow in the starting phase of the DC system, realize a non-impact and controllable starting process, protect system equipment, optimize system performance, and ensure the safe and efficient operation of the high-voltage direct current transmission system.

[0060] The method further comprises: obtaining an IGCT characteristic parameter of the first main valve and an IGCT characteristic parameter of the second main valve, wherein the IGCT characteristic parameter comprises a current characteristic of the IGCT; determining a direct current rising rate and a direct voltage rising rate according to at least the IGCT characteristic parameter of the first main valve and the IGCT characteristic parameter of the second main valve, the direct current rising rate being a rising rate of the direct current for controlling the starting of the first main valve, and the direct voltage rising rate being a rising rate of the direct voltage for controlling the starting of the second main valve. Specifically, the current characteristic of the IGCT comprises a rising rate of the current of the IGCT, which indicates the speed of the current change with time in the switching process of the IGCT, and is one of the key parameters for measuring the dynamic switching performance of the IGCT, directly affecting the reliability of the device, the circuit design and the system stability.

[0061] The current characteristics of the IGCT include turn-on delay time, current rise time, and turn-on overshoot current. The turn-on delay time is the time required for the anode current to rise to 10% of the rated current after the application of a positive driving signal to the gate. The current rise time is the time required for the anode current to rise from 10% to 90% of the rated current, which directly determines the di / dt (i.e., the rate of current rise). The shorter the current rise time, the greater the di / dt, and the faster the switching speed, but the higher the risk associated with di / dt. The turn-on overshoot current is the peak value of the current at the initial stage of turn-on, which is usually 1.1-1.5 times I_T, and is caused by circuit parasitic parameters such as capacitor discharge. Of course, the main parameter that affects the rate of rise of direct current is the rate of rise of current of the IGCT.

[0062] By obtaining the characteristic parameters of the converter IGCT (Insulated Gate Bipolar Transistor), including current carrying capacity, voltage tolerance range, and thermal characteristics, etc., the current characteristics of the IGCT are mainly considered in this scheme. The start-up control strategy can be adjusted according to the specific characteristics and state of each converter, realizing personalized start-up control and ensuring the stability and safety of the equipment during start-up.

[0063] The way of determining the rate of rise of direct current and the rate of rise of direct voltage according to the IGCT characteristic parameters of the first main valve and the IGCT characteristic parameters of the second main valve can coordinate the power transmission between the first main valve and the second main valve. In the initial stage of the start-up process, the rates of rise of direct current and voltage need to match the characteristics of the IGCT to avoid power backfeed or system oscillation caused by mismatched rates of rise, ensuring smooth power transition between the sending end and the receiving end.

[0064] In addition, the start-up control based on IGCT characteristic parameters can more accurately predict the start-up time of the converter and optimize energy consumption during the start-up process. By setting appropriate rates of rise of direct current and voltage, the start-up time and energy consumption can be balanced, thereby improving the start-up efficiency and reducing the impact on the power grid during the start-up process.

[0065] By precisely controlling the rates of rise of direct current and voltage, energy loss during the start-up process can be reduced, especially when the IGCT is in the low-efficiency working region. This not only improves the economy of the start-up phase, but also helps the entire high-voltage direct current transmission system to reach a high-efficiency operating state more quickly after start-up.

[0066] The smooth rise of direct current and voltage not only contributes to the safe start-up of the IGCT, but also has a positive impact on the stability of the entire direct current transmission system. Voltage and current surges during the start-up process are avoided, reducing the risk of system oscillation and ensuring smooth operation of the system after start-up.

[0067] Specifically, a preset correspondence between the IGCT characteristic parameters of the first and second main valves and the DC current and voltage rise rates is constructed based on historical data and analysis, and the DC current and voltage rise rates are accurately determined according to the preset correspondence.

[0068] In a more specific implementation, the DC current and voltage rise rates are determined based on at least the IGCT characteristic parameters of the first and second main valves, including: obtaining a main protection mechanism of the DC system, wherein the main protection mechanism is adapted to the start-up rate of the DC system, and the main protection control is triggered if the DC current rise rate is greater than a preset current rise rate and / or the DC voltage rise rate is greater than a preset voltage rise rate.

[0069] The DC current and voltage rise rates are determined based on the IGCT characteristic parameters of the first and second main valves and the main protection mechanism.

[0070] That is, the factors for determining the DC current and voltage rise rates not only consider the IGCT characteristic parameters of the first and second main valves, but also take the main protection mechanism into account, because the DC current and voltage rise too fast will trigger the main protection control, that is, the main protection mechanism limits the upper limit of the DC current and voltage rise rates, and the DC current and voltage rise rates need to ensure the safe and stable operation of the IGCTs of the first and second main valves. The DC current and voltage rise rates determined by combining these two factors can better ensure the start-up efficiency and safety of the system.

[0071] Therefore, combining the start-up rate control based on the IGCT characteristic parameters with the main protection mechanism can not only improve the safety and stability of the equipment and system, but also optimize the start-up process, reduce start-up loss, and enhance the adaptability to environmental changes, which is an important progress in intelligent control of high-voltage direct current transmission systems. In this way, more efficient and reliable power transmission can be achieved.

[0072] In a specific implementation, the DC current and voltage rise rates are determined based on the IGCT characteristic parameters of the first and second main valves and the main protection mechanism, including:

[0073] The current change rate tolerance upper limit of the IGCT in the first main valve is determined based on the IGCT characteristic parameters of the first main valve, and the current change rate tolerance upper limit of the IGCT in the second main valve is determined based on the IGCT characteristic parameters of the second main valve.

[0074] The direct current rise rate and the direct voltage rise rate are determined based on constraints, including: a current change rate applied to the IGCT in the first main valve during the starting process is lower than an upper limit of the current change rate tolerance of the IGCT in the first main valve, a current change rate applied to the IGCT in the second main valve during the starting process is lower than an upper limit of the current change rate tolerance of the IGCT in the second main valve, and a main protection mechanism is not triggered.

[0075] By determining the upper limit of the current change rate tolerance of the IGCT, the current rise rate during the starting process can be strictly limited, avoiding the risk of the IGCT exceeding its safe working interval during the starting phase, thereby effectively protecting the IGCT from overheating or damage caused by sudden current changes and strengthening the safety management of the equipment.

[0076] Based on the upper limit of the current change rate tolerance of the IGCT, the control system can accurately plan the rise rate of the direct current and voltage, ensuring that the starting process is both fast and safe. By optimizing the starting strategy, the time required for starting can be reduced while ensuring that the IGCT does not bear stress beyond its tolerance range, improving the efficiency of the starting process and the service life of the equipment.

[0077] By avoiding the IGCT from bearing excessive current change rate during the starting process, the probability of equipment failure is reduced, and at the same time, due to the reduction in failure rate, maintenance costs and downtime are also indirectly reduced, improving the economic efficiency and availability of the system.

[0078] The direct current rise rate and the direct voltage rise rate determined under the constraints that the current change rate applied to the IGCT in the first main valve during the starting process is lower than the upper limit of the current change rate tolerance of the IGCT in the first main valve, the current change rate applied to the IGCT in the second main valve during the starting process is lower than the upper limit of the current change rate tolerance of the IGCT in the second main valve, and the main protection mechanism is not triggered, ensure that the system starts safely while avoiding false entry into the main protection control.

[0079] In a specific implementation, the direct current rise rate and the direct voltage rise rate are determined according to the IGCT characteristic parameters of the first main valve, the IGCT characteristic parameters of the second main valve, and the main protection mechanism, including:

[0080] A preset mapping relationship is constructed, the preset mapping relationship representing the relationship between cause variables and result variables, the cause variables including the IGCT characteristic parameters of the first main valve, the IGCT characteristic parameters of the second main valve, and the main protection mechanism, and the result variables including the direct current rise rate and the direct voltage rise rate;

[0081] The current result variable is determined according to the preset mapping relationship and the current cause variable, and the current cause variable includes the IGCT characteristic parameter of the current first main valve, the IGCT characteristic parameter of the current second main valve and the current main protection mechanism, and the current result variable includes the current DC current rising rate and the current DC voltage rising rate.

[0082] By using the preset mapping relationship, the rising rates of the DC current and voltage can be dynamically adjusted according to the real-time characteristic parameters of the current IGCT and the state of the main protection mechanism. This dynamic adaptability ensures that the start-up control strategy can respond to the state changes of the equipment and system in real time, improving the flexibility of control and the reliability of the system.

[0083] The preset mapping relationship is essentially an intelligent prediction model that converts device state parameters into control strategy parameters. Based on historical data and analysis, it can predict the optimal DC current and voltage rising rates under specific IGCT characteristic parameters and main protection mechanism conditions. This intelligent decision support enables the control system to more accurately adjust the start-up parameters, avoiding unnecessary energy waste and device stress, and improving start-up efficiency.

[0084] The preset mapping relationship ensures that the rising rates of the DC current and voltage are always within the safe operating boundaries of the IGCT, while pursuing optimal start-up performance. It effectively balances start-up speed and device safety, avoiding device overload or system failure caused by improper start-up parameter settings, thereby achieving safe and controllable and fast response in the start-up process.

[0085] Once the preset mapping relationship is established and integrated into the control system, the start-up strategy can be automatically adjusted according to the current device state and protection mechanism, reducing the dependence on manually set parameters.

[0086] The construction of the preset mapping relationship relies on the analysis of a large amount of historical data and device operation data. This data-driven optimization method not only improves the accuracy of start-up control, but also, as data accumulates, the mapping relationship will become more perfect, and the start-up strategy will be more optimized.

[0087] The method further comprises: before and during the start-up, predicting potential faults by monitoring the characteristic parameters of the devices in the sending-end converter valve and the receiving-end converter valve, and if a potential fault is detected, adaptively adjusting the DC current rising rate and the DC voltage rising rate to enhance the self-recovery capability of the system, wherein the devices in the sending-end converter valve and the receiving-end converter valve include IGCT, IGBT and diode, and the characteristic parameters of the devices include electrical characteristic parameters and temperature characteristic parameters, the electrical characteristic parameters specifically include current change rate tolerance upper limit, turn-on voltage drop, turn-off voltage and other parameters; and the temperature parameters include device junction temperature.

[0088] In a specific implementation, if the current change rate of the IGCT, IGBT and diode is higher than or close to the upper limit of the current change rate tolerance, it indicates that there is a potential fault; if the on-state voltage drop deviates from the preset on-state voltage drop by more than a preset range, it indicates that there is a potential fault, where the preset range is a range that ensures normal operation of the device; if the off-state voltage deviates from the preset off-state voltage by more than a preset range, it indicates that there is a potential fault, where the preset range is a range that ensures normal operation of the device; if the device junction temperature deviates from the preset junction temperature by more than a preset range, it indicates that there is a potential fault, where the preset range is a range that ensures normal operation of the device.

[0089] If a potential fault is detected, the DC current rise rate and the DC voltage rise rate are adaptively adjusted, which is specifically implemented as follows: according to the deviation of the characteristic parameter from the preset value or the preset range, the DC current rise rate and the DC voltage rise rate are adjusted, for example, the greater the deviation of the characteristic parameter from the preset value or the preset range, the greater the adjustment amplitude of the DC current rise rate and the DC voltage rise rate; the smaller the deviation of the characteristic parameter from the preset value or the preset range, the smaller the adjustment amplitude of the DC current rise rate and the DC voltage rise rate; of course, the premise of this adjustment is to ensure the safe start of the DC system.

[0090] If a potential fault is detected, the DC current rise rate and the DC voltage rise rate are adaptively adjusted, which is also specifically implemented as follows: an adaptive adjustment algorithm is used to adaptively adjust the DC current rise rate and the DC voltage rise rate according to the characteristic parameter deviating from the preset value or the preset range, and a relationship between the deviation of the parameter of the adaptive adjustment algorithm from the characteristic parameter is established, and then the adjusted DC current rise rate and the adjusted DC voltage rise rate are adaptively output according to the deviation of the input characteristic parameter. The adaptive adjustment algorithm can be selected from a model reference adaptive control model (MRAC, Model Reference Adaptive Control), an adaptive particle swarm optimization (APSO, Adaptive Particle Swarm Optimization), etc.

[0091] The method further comprises: applying a machine learning algorithm to learn and optimize the direct current rise rate and the direct voltage rise rate according to historical starting data and device operating states, so that the system can automatically identify the optimal starting strategy, reduce the dependence on manual setting of parameters, and improve the intelligence and adaptability of control. The historical starting data specifically comprises: process parameters and result parameters, the process parameters comprising a set di / dt, a set du / dt, a peak current, and a trigger angle, and the result parameters comprising a total starting duration, an overcurrent frequency, and a commutation failure frequency; and the device operating state specifically comprises a device state, the device state comprising an accumulated operating duration, a junction temperature, and a conduction voltage drop change amount, and the device state reflecting the device tolerance, so that the model matches the upper limit of the rise rate of the current hardware.

[0092] Specifically, the step of starting the first support valve and the second support valve comprises:

[0093] In the case that the direct voltage of the first support valve and the second support valve is charged to a preset voltage, the first support valve and the second support valve are unlocked; for example, the preset voltage is 0.5 p.u., and of course the specific value of the preset voltage can be adjusted according to the specific structure of the first support valve and the second support valve.

[0094] The charging of the first support valve and the second support valve is continued until the direct voltage of the first support valve and the second support valve is charged to a rated voltage, and it is determined that the starting of the first support valve and the second support valve is completed, and the preset voltage is less than the rated voltage. The rated voltage is charged to 1.0 p.u.

[0095] By setting the first support valve and the second support valve to be unlocked when the direct voltage reaches the preset voltage, it is ensured that the converter accurately changes from the uncontrolled charging state to the controllable state. This accurate control avoids the situation that the converter cannot be normally unlocked due to too low direct voltage, or the current impact and overvoltage caused by unlocking when the direct voltage is too high, thereby improving the control accuracy of the entire starting process.

[0096] After the support valve is unlocked, the process of continuing to charge to 1.0 p.u. ensures the smooth transition of the direct voltage from the unlocked state to the steady state. This process avoids the influence of voltage mutation on power devices, ensures the smooth coordination of power within the converter, and is also conducive to the coordinated operation between the sending end and the receiving end converters, ensuring the smoothness and stability of the entire high-voltage direct current transmission system starting process.

[0097] In some embodiments, the first main valve is controlled by a direct current to start the first main valve, and the second main valve is controlled by a direct voltage to start the second main valve, comprising:

[0098] The first main valve is controlled by a direct current and a first PI control loop to start the first main valve;

[0099] The second main valve is controlled based on a DC voltage and a second PI control loop to start up the second main valve.

[0100] The PI control loops provide precise control over DC current and DC voltage, enabling real-time adjustment of control signals to respond to changes in system state. The first PI control loop controls the DC current of the first main valve, ensuring a smooth ramp-up of current at a predetermined slope and preventing sudden changes in current that could cause equipment overload or voltage disturbances. Similarly, the second PI control loop controls the DC voltage of the second main valve, ensuring a steady increase in voltage to the set value and avoiding potential system instability due to voltage fluctuations.

[0101] The control strategy based on DC current and the first PI control loop ensure a stable increase in power output during the startup process of the first main valve (typically located at the sending end). Meanwhile, the control strategy based on DC voltage and the second PI control loop ensure a smooth increase in voltage level for the second main valve (typically located at the receiving end), meeting the requirements for power reception. This control method ensures coordinated startup between the sending-end and receiving-end converters, avoiding issues such as power backfeeding or voltage and current imbalance caused by mismatched startup control.

[0102] In addition, the PI control loops can dynamically adjust control signals based on the characteristic parameters of power devices such as IGCT or IGBT, to prevent excessive stress on equipment during startup. For example, the first PI control loop can limit the startup current of the first main valve to be below a safety threshold based on the current characteristics of IGCT, and the second PI control loop can control the startup voltage of the second main valve to be within the voltage withstand range of the device based on the voltage characteristics of IGBT.

[0103] The startup control method of the DC system of the present application is applied to Figure 2 a DC system as shown, Figure 2 only the receiving end of the DC system is shown, and the structure of the sending end is similar to that of the receiving end.

[0104] The DC system includes a sending end and a receiving end, the sending end includes a sending-end converter valve and a sending-end charging resistor, the receiving end includes a receiving-end converter valve and a receiving-end charging resistor, the sending-end converter valve includes a first main valve and a first support valve, the receiving-end converter valve includes a second main valve and a second support valve, the first main valve and the second main valve are IGCT straight string valves, and the IGCT straight string valve is a three-phase six-bridge-arm IGCT straight string valve (see Figure 2 the three-phase six-bridge-arm IGCT straight string valve shown), and the first support valve and the second support valve include full-bridge modules, see Figure 2 the full-bridge module includes a bridge arm of IGBT and diode in parallel and a capacitor.

[0105] The startup principle of the single-end converter valve of the DC power transmission system can be found in Figure 3, the controller input signals are all locking signals (0) before the main valve and the support valve unlocking signal is issued, at this time, since the support valve adopts a full-bridge sub-module, it can be charged under the action of grid voltage by using a diode path without control, when the support is charged to a certain value, with the issuance of the support valve unlocking signal, the support enters the controllable charging stage, under the action of sub-module capacitor voltage equalization control, the support can be charged to the rated voltage. At the same time, under the action of reactive power control, the support can realize the reactive power balance of the main valve without increasing additional reactive power compensation devices, without exchanging reactive power with the grid. Specifically, Figure 3 The sub-module SM in the full-bridge module includes an IGBT and a diode in parallel in any bridge arm, and further includes a capacitor in parallel with the upper and lower bridge arms.

[0106] The dq-axis components output by the sub-module capacitor voltage control and the reactive power control pass through a closed-loop decoupling controller and a nearest level approximation modulation link to generate a trigger signal for controlling the switching of the support valve devices.

[0107] For the main valve, the sending and receiving end converter control targets are different, when the support valve is charged to the steady state, the sending and receiving end main valve can be unlocked, at this time, the sending end is based on the constant DC current control, and the receiving end is based on the constant DC voltage control, under the synergistic action of the two control targets, the DC system active power control can be realized. The DC voltage and DC current start instructions can be set according to the actual situation.

[0108] In summary, in the start-up control strategy of the single-end converter valve, the control strategies of the sending and receiving end converter support valves are the same, but the control strategies of the sending and receiving end converter main valves are different, mainly reflected in the inconsistency of the control targets.

[0109] In addition, the specific implementation of the start-up control method of the DC system in the above embodiment can be applied to Figure 2 the DC system shown in the figure, which will not be repeated here.

[0110] The start-up control method of the DC system of the present application is also applied to Figure 4 the DC system shown in the figure, Figure 4 only the receiving end of the DC system is shown, and the sending end and the receiving end have similar structures. The DC system includes a sending end and a receiving end, the sending end includes a sending end converter valve, a sending end charging resistor and a transformer set, the receiving end includes a receiving end converter valve and a receiving end charging resistor and a transformer set, the sending end converter valve includes a first main valve and a first support valve, the receiving end converter valve includes a second main valve and a second support valve, the first main valve and the second main valve are IGCT straight string valves, and the IGCT straight string valve is a three-phase twelve-bridge-arm IGCT straight string valve Figure 4As shown in the figure, the first support valve and the second support valve are two sets of three-phase full-bridge modules. Each transformer group includes two star-delta connected transformers. The transformer connected to the first set of three-phase six-bridge arms is a star-delta connected transformer, and the transformer connected to the second set of three-phase six-bridge arms is also a star-delta connected transformer.

[0111] A 12-pulse converter is formed by cascading two six-pulse converters. By controlling the triggering sequence of the six-pulse converters, the DC voltage can be increased from 6 pulses to 12 pulses, which helps reduce DC voltage ripple and improve power quality. Since the support valve has the ability to filter harmonics, the two six-pulse converters do not need to use phase-shifting converter transformers to cancel the 5th and 7th harmonics. Both can use star-delta connected transformers, which can reduce the manufacturing difficulty and cost of the converter transformer.

[0112] The specific implementations of the DC system startup control method in the above embodiments can all be applied to Figure 4 The DC system shown will not be described in detail here.

[0113] Figure 5 It also shows a method applicable to Figure 2 and Figure 4 The starting control method for a DC system specifically includes:

[0114] (1) Confirm the start command, lock the F3C-HVDC subsystem rectifier-side converter (i.e., the sending-end converter valve) and inverter station converter (i.e., the receiving-end converter valve), and disconnect the mechanical switch to put the charging resistor into the support valve;

[0115] (2) The circuit breakers on the grid side of the converter transformers of the F3C-HVDC subsystem rectifier side and inverter side converter station are closed respectively, so that the converter transformers and F3C support valves are energized and enter the uncontrolled charging stage.

[0116] (3) When the DC voltage of the support valves on the rectifier side and the inverter side is charged to 0.5pu, the support valves are unlocked to allow them to enter the controllable charging stage;

[0117] (4) After the two support valves are charged to 1.0pu through closed-loop voltage control and reach a steady state, the mechanical switch is closed to cut off the charging resistor. At this time, the support valve is started.

[0118] (5) After the DC voltage of the support valve reaches the rated value, the main valves of the rectifier side and the inverter side are unlocked at the same time. The rectifier side converter adopts constant DC current control and adjusts the current according to the reference value of the specified slope. The inverter side converter adopts constant DC voltage control and adjusts the voltage according to the reference value of the specified slope until the steady state is reached.

[0119] (6) When the active power reaches 1.0 pu, the F3C-HVDC system startup process ends and enters the steady-state operation stage.

[0120] The starting characteristics of the starting control method of the direct current system involved herein are described with reference to Figure 6 As shown in Figure 6 (a) As shown in Figs. 6(b), the starting process of the F3C-HVDC system has two obvious stages. The support valve completes the starting and reaches the steady state at 0.5 s, and the main valve is unlocked at 0.8 s and formally enters the starting process. In the starting process, the rectifier side and the inverter side converters are kept in the unit power factor working condition and can steadily increase the transmission power.

[0121] In the F3C-HVDC subsystem, the rectifier side (i.e., the sending end) adopts the constant direct current control, and the inverter side (i.e., the receiving end) adopts the constant direct voltage control. In the starting process, the voltages and currents of the converters on both sides can track the reference values in real time, as shown in Figure 6 (c) As shown in Figs. 6(d), in the scheme, the slope of the direct voltage reference value of the inverter side is less than the slope of the direct current reference value of the rectifier side (KUdc_ref < KIdc_ref). This is to ensure that the direct voltage of the rectifier side is greater than the direct voltage of the inverter side (UdcR > UdcI), so as to ensure that the power of the direct current system is always positively flowed from the rectifier side to the inverter side.

[0122] The direct voltage waveform of the valve arm of the support valve is shown in Figure 6 (e). In the uncontrolled stage, the rectifier side and the inverter side support valves are charged to 0.5 p.u. respectively. At this time, the support valve only absorbs a small amount of active power. When entering the controllable charging stage, the support absorbs a large amount of active power, and the peak value of the direct voltage of the valve arm is about 1.6 p.u. Since the voltage utilization rate of the device in the support valve is often designed according to 50%, the withstand voltage limit is 2.0 p.u. Therefore, it can be seen that the starting process of the support valve in this paper is still within the withstand range of the equipment. At the same time, after the main valve is unlocked, the direct voltage of the valve arm of the support valve basically maintains the rated value, only a slight fluctuation occurs, which further illustrates the feasibility of the starting scheme.

[0123] The trigger angles of the rectifier side and the inverter side in the F3C-HVDC subsystem are shown in Figure 6 (f). In the starting process, the trigger angle α of the rectifier side is continuously reduced to increase the direct voltage so as to track the current command value, and the trigger angle of the inverter side is the same.

[0124] The bridge arm currents of the rectifier side and the inverter side in the F3C-HVDC subsystem are shown in Figure 6 (g). After the main valve is unlocked, the system starts normal starting. At this time, the outlet current Ip of the main valve, the outlet current Ic of the support valve and the grid current Ig start to gradually increase, and finally tend to be stable.

[0125] The bridge arm voltages of the rectifier side and the inverter side in the F3C-HVDC subsystem are shown in Figure 6(h) as shown. The valve voltage pulsation range depends on the firing angle, as the starting process proceeds, the rectifier side firing angle alpha and the inverter side firing angle beta gradually decrease, so that the valve voltage peak gradually decreases.

[0126] Therefore, the F3C-HVDC direct current system step-by-step starting strategy can realize the starting function, that is, firstly completing the starting of the support valve, then unlocking the support valve, and finally realizing the starting of the whole system. The support valve will bear overvoltage in the controllable charging process, and the overvoltage is determined by the delta control loop. Through analysis, it is found that the overvoltage will not exceed the design limit value of the equipment under the existing control parameters, and the starting can be successfully completed.

[0127] In summary, the application proposes a no-impact starting control strategy suitable for the 3C converter, which solves the problems of internal power coordination of the main valve and the support valve and power coordination of the sending and receiving end direct current system during the starting process of the composite converter. Under the starting control strategy of the converter proposed in the application, the F3C converter direct current voltage and direct current can be output according to the instruction value, the active power transmitted by the F3C converter to the power grid smoothly increases from 0 to the rated value, and the reactive power exchanged between the converter and the power grid can always maintain reactive power balance (the reactive power exchange between the converter and the power grid is 0) under the coordination of the support valve, without the need to configure an additional reactive power compensation device. At the same time, under the starting control strategy of the converter proposed in the application, the main valve direct current voltage and the support valve bridge arm direct current voltage are not obviously overvoltage, which indicates that the strategy can realize the no-impact starting of the F3C converter.

[0128] The sending end converter valve and the receiving end converter valve in the closed state, or the closed sending end converter valve and the receiving end converter valve, involved in the embodiments of the application, are specifically explained as follows:

[0129] The "closed converter valve" refers to the action of stopping sending the trigger pulse to the converter valve, so that the current flow path is cut off. Once the converter valve is closed, the controllable devices (such as thyristors, IGBTs, IGCTs) in the converter valve will no longer conduct, and the converter will stop energy transmission.

[0130] The sending end converter valve and the receiving end converter valve in the unlocked state, or the unlocked sending end converter valve and the receiving end converter valve, involved in the embodiments of the application, are specifically explained as follows: the lock on the trigger pulse of the converter valve is released, so that the sending end converter valve and the receiving end converter valve are in the unlocked state, and have normal conduction and commutation capability, thereby allowing the converter to start the process of AC-DC power conversion.

[0131] The embodiment of the present application further provides a starting control device of a DC system. It should be noted that the starting control device of the DC system of the embodiment of the present application can be used to execute the starting control method of the DC system provided by the embodiment of the present application. The device is used to realize the above-mentioned embodiment and preferred embodiment, and the description has been made and will not be repeated. As used below, the term "module" can be a combination of software and / or hardware that realizes a predetermined function. Although the device described in the following embodiment is preferably realized in software, the realization of hardware or a combination of software and hardware is also possible and conceived.

[0132] The starting control device of the DC system provided by the embodiment of the present application is introduced below. The device is used to realize the starting control method of the DC system. The DC system includes a sending end and a receiving end. The sending end includes a sending end converter valve, a sending end charging resistor and a first switch connected in parallel with the sending end charging resistor. The receiving end includes a receiving end converter valve, a receiving end charging resistor and a second switch connected in parallel with the receiving end charging resistor. The sending end converter valve includes a first main valve and a first support valve. The receiving end converter valve includes a second main valve and a second support valve. The first main valve and the second main valve are IGCT straight string valves. The first support valve and the second support valve include full-bridge modules. The starting control device of the DC system includes:

[0133] A first control unit is configured to control the first switch and the second switch to be turned off to control the sending end charging resistor and the receiving end charging resistor to be connected to the DC system when the sending end converter valve and the receiving end converter valve are in a blocking state.

[0134] A second control unit is configured to control the sending end and the receiving end to be powered on and perform the step of starting the first support valve and the second support valve after a starting signal is activated. The activation of the starting signal indicates that the starting process is entered.

[0135] A third control unit is configured to control the first switch and the second switch to be turned on to control the sending end charging resistor and the receiving end charging resistor not to be connected to the DC system and to unlock the first main valve and the second main valve after the starting of the first support valve and the second support valve is completed. Then, the first main valve is started by using a DC current, and the second main valve is started by using a DC voltage.

[0136] The starting control device of the DC system of the present application can realize the safe and non-impact starting of the F3C converter and the DC power transmission system constituted by the F3C converter, ensure the smooth and controllable starting process, improve the operation efficiency and reliability of the system, optimize the reactive power management, and reduce the system cost. It is a high-efficiency and practical starting control strategy. The problem that there is no starting scheme for the DC system based on the full-control composite converter which takes into account the accurate power transmission and smooth power transition is solved.

[0137] In the embodiments of the present application, the third control unit comprises a first control module and a second control module. The first control module is configured to control the first main valve by using an increasing direct current to start the first main valve, and the rising rate of the direct current is a direct current rising rate. The second control module is configured to control the second main valve by using an increasing direct current to start the second main valve, and the rising rate of the direct current is a direct current rising rate, and the dimensionless quantity of the direct current rising rate is less than the dimensionless quantity of the direct current rising rate.

[0138] The device further comprises an acquisition unit and a determination unit. The acquisition unit is configured to acquire the IGCT characteristic parameters of the first main valve and the IGCT characteristic parameters of the second main valve, wherein the IGCT characteristic parameters comprise current characteristics of the IGCT. The determination unit is configured to determine the direct current rising rate and the direct current rising rate according to at least the IGCT characteristic parameters of the first main valve and the IGCT characteristic parameters of the second main valve. The direct current rising rate is the rising rate of the direct current for controlling the start of the first main valve, and the direct current rising rate is the rising rate of the direct current for controlling the start of the second main valve.

[0139] The determination unit comprises a first acquisition module and a first determination module. The first acquisition module is configured to acquire the main protection mechanism of the direct current system, wherein the main protection mechanism is adapted to the start rate of the direct current system, and the main protection control is triggered if the direct current rising rate is greater than a preset current rising rate and / or the direct current rising rate is greater than a preset voltage rising rate. The first determination module is configured to determine the direct current rising rate and the direct current rising rate according to the IGCT characteristic parameters of the first main valve, the IGCT characteristic parameters of the second main valve and the main protection mechanism.

[0140] The first determination module comprises a first determination submodule and a second determination submodule. The first determination submodule is configured to determine the upper limit of the current change rate tolerance of the IGCT in the first main valve according to the IGCT characteristic parameters of the first main valve, and determine the upper limit of the current change rate tolerance of the IGCT in the second main valve according to the IGCT characteristic parameters of the second main valve. The second determination submodule is configured to determine the direct current rising rate and the direct current rising rate based on a constraint condition, wherein the constraint condition comprises: the current change rate applied to the IGCT in the first main valve during the start process is lower than the upper limit of the current change rate tolerance of the IGCT in the first main valve, the current change rate applied to the IGCT in the second main valve during the start process is lower than the upper limit of the current change rate tolerance of the IGCT in the second main valve, and the main protection mechanism is not triggered.

[0141] The first determining module comprises a constructing submodule and a third determining submodule. The constructing submodule is configured to construct a preset mapping relationship, and the preset mapping relationship represents a relationship between a cause variable and a result variable. The cause variable comprises an IGCT characteristic parameter of the first main valve, an IGCT characteristic parameter of the second main valve, and a main protection mechanism. The result variable comprises a direct current current rise rate and a direct current voltage rise rate. The third determining submodule is configured to determine a current result variable according to the preset mapping relationship and a current cause variable. The current cause variable comprises a current IGCT characteristic parameter of the first main valve, a current IGCT characteristic parameter of the second main valve, and a current main protection mechanism. The current result variable comprises a current direct current current rise rate and a current direct current voltage rise rate.

[0142] Specifically, the second control unit comprises an unlocking module and a charging module. The unlocking module is configured to unlock the first support valve and the second support valve when the direct current voltage of the first support valve and the second support valve is charged to a preset voltage. The charging module is configured to continue charging the first support valve and the second support valve until the direct current voltage of the first support valve and the second support valve is charged to a rated voltage, and determine that the first support valve and the second support valve are started up completely. The preset voltage is less than the rated voltage.

[0143] The third control unit comprises a third control module and a fourth control module. The third control module is configured to control the first main valve to start up the first main valve based on the direct current and by applying a first PI control loop. The fourth control module is configured to control the second main valve to start up the second main valve based on the direct current voltage and by applying a second PI control loop.

[0144] The technical advantages of the starting control method of the direct current system are also applicable to the starting control device of the direct current system.

[0145] The starting control device of the direct current system comprises a processor and a memory. The first control unit and the like are stored in the memory as program units, and the corresponding functions are realized by the processor executing the program units stored in the memory. The modules are located in the same processor, or the modules are located in different processors in any combination.

[0146] The processor comprises a core, and the core retrieves the corresponding program unit from the memory. The core can be one or more, and the problem that the prior art lacks a starting scheme for a direct current system based on a full-control composite converter, which takes into account accurate power transmission and smooth power transition, can be solved by adjusting the core parameters.

[0147] The memory can comprise a non-permanent memory in a computer readable medium, a random access memory (RAM), and / or a non-volatile memory such as a read-only memory (ROM) or a flash memory (flash RAM), and the memory comprises at least one memory chip.

[0148] The embodiment of the present application provides a computer readable storage medium, which comprises a stored program, wherein the computer readable storage medium controls a device where the computer readable storage medium is located to execute the starting control method of the direct current system when the program is run.

[0149] The embodiment of the present application provides a processor, which is used for running a program, wherein the processor executes the starting control method of the direct current system when the program is run.

[0150] The embodiment of the present application provides a device, which comprises a processor, a memory and a program stored in the memory and capable of running on the processor, and the processor executes the steps of the starting control method of the direct current system when the program is run. The device herein can be a server, a PC, a PAD, a mobile phone and the like.

[0151] The present application also provides a computer program product, which is suitable for executing the steps of the starting control method of the direct current system when the computer program product is executed on a data processing device.

[0152] Obviously, those skilled in the art should understand that the modules or steps of the present application described above can be realized by general computing devices, and they can be concentrated on a single computing device or distributed on a network composed of multiple computing devices, and they can be realized by program codes executable by the computing devices, so that they can be stored in storage devices and executed by the computing devices, and in some cases, the steps shown or described herein can be executed in different sequences, or they can be manufactured into individual integrated circuit modules respectively, or multiple modules or steps among them can be manufactured into a single integrated circuit module to realize. Thus, the present application is not limited to any particular combination of hardware and software.

[0153] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system or a computer program product. Therefore, the present application can adopt a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware aspects. Moreover, the present application can adopt a computer program product in the form of being implemented on one or more computer usable storage media (including but not limited to disk storage, CD-ROM, optical storage and the like) containing computer usable program codes.

[0154] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 means for functionally implementing the steps listed in the flowchart block or blocks.

[0155] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 means for functionally implementing the steps listed in the flowchart block or blocks.

[0156] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 means for functionally implementing the steps listed in the flowchart block or blocks.

[0157] In one typical configuration, the computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0158] The memory can include non-persistent memory and / or volatile memory, such as random access memory (RAM) and / or cache memory, for storing instructions and data used and / or generated by the computing device. The memory can also include non-volatile memory, such as read-only memory (ROM), electrically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, or nonvolatile random access memory (RAM) (e.g., fault tolerant RAM), for storing instructions and data used and / or generated by the computing device. The memory can also include a storage device, such as a disk drive, hard drive, or flash storage, for storing instructions and data used and / or generated by the computing device. The memory can be embodied in an article of manufacture that includes one or more computer program instructions.

[0159] Computer-readable media includes permanent and non-permanent, movable and non-movable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette, magnetic tape disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible to a computing device. According to the definition herein, computer-readable media does not include transitory media such as modulated data signals and carriers.

[0160] It should also be noted that the terms "comprising", "containing", or any other variant thereof are intended to cover non-exclusive inclusions, so that a process, method, article or apparatus that includes a list of elements not only includes those elements, but also includes other elements not explicitly listed, or inherent to such a process, method, article or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus that includes the element.

[0161] The technical features of the above-described embodiments can be combined in any manner. In order to make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, however, as long as the combinations of the technical features do not contradict each other, they should be considered within the scope of the present disclosure.

[0162] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method of starting control of a direct current system, characterized by, The direct current system comprises a sending end and a receiving end, the sending end comprises a sending end converter valve, a sending end charging resistor and a first switch connected in parallel with the sending end charging resistor, the receiving end comprises a receiving end converter valve, a receiving end charging resistor and a second switch connected in parallel with the receiving end charging resistor, the sending end converter valve comprises a first main valve and a first support valve, the receiving end converter valve comprises a second main valve and a second support valve, the first main valve and the second main valve are IGCT straight string valves, the first support valve and the second support valve comprise full-bridge modules, and the starting control method comprises: controlling the first switch and the second switch to be turned off to control the sending end charging resistor and the receiving end charging resistor to be connected to the direct current system when the sending end converter valve and the receiving end converter valve are in a blocking state; controlling the sending end and the receiving end to be powered on after a starting signal is activated, and performing the step of starting the first support valve and the second support valve, and the starting signal being activated represents entering a starting process; controlling the first switch and the second switch to be turned on to control the sending end charging resistor and the receiving end charging resistor not to be connected to the direct current system and to unlock the first main valve and the second main valve after the first support valve and the second support valve are started, and then controlling the first main valve to be started by using a direct current and controlling the second main valve to be started by using a direct voltage.

2. The start-up control method of a DC system according to claim 1, characterized by, controlling the first main valve to be started by using an increasing direct current, and controlling the second main valve to be started by using an increasing direct voltage, wherein the increasing rate of the direct current is a direct current increasing rate, and the increasing rate of the direct voltage is a direct voltage increasing rate, and the dimensionless quantity of the direct voltage increasing rate is less than the dimensionless quantity of the direct current increasing rate. The method further comprises: obtaining IGCT characteristic parameters of the first main valve and IGCT characteristic parameters of the second main valve, wherein the IGCT characteristic parameters comprise current characteristics of IGCT; 3. The start-up control method of a DC system according to claim 1, characterized by, determining the direct current increasing rate and the direct voltage increasing rate according to at least the IGCT characteristic parameters of the first main valve and the IGCT characteristic parameters of the second main valve, wherein the direct current increasing rate is the increasing rate of the direct current for controlling the first main valve to be started, and the direct voltage increasing rate is the increasing rate of the direct voltage for controlling the second main valve to be started. determining the direct current increasing rate and the direct voltage increasing rate according to at least the IGCT characteristic parameters of the first main valve and the IGCT characteristic parameters of the second main valve, comprises: obtaining a main protection mechanism of the direct current system, wherein the main protection mechanism is adapted to a starting rate of the direct current system, and the main protection control is triggered if the direct current increasing rate is greater than a preset current increasing rate and / or the direct voltage increasing rate is greater than a preset voltage increasing rate.

4. The start-up control method of a DC system according to claim 3, characterized by, ​ ​ determining the DC current rise rate and the DC voltage rise rate according to the IGCT characteristic parameters of the first main valve, the IGCT characteristic parameters of the second main valve and the main protection mechanism comprises:

5. The start-up control method of a DC system according to claim 4, characterized by, determining the DC current rise rate and the DC voltage rise rate according to the IGCT characteristic parameters of the first main valve, the IGCT characteristic parameters of the second main valve and the main protection mechanism comprises: determining the current change rate tolerance upper limit of the IGCT in the first main valve according to the IGCT characteristic parameters of the first main valve, and determining the current change rate tolerance upper limit of the IGCT in the second main valve according to the IGCT characteristic parameters of the second main valve; determining the DC current rise rate and the DC voltage rise rate based on a constraint condition, the constraint condition comprising: the current change rate applied to the IGCT in the first main valve during the starting process being lower than the current change rate tolerance upper limit of the IGCT in the first main valve, the current change rate applied to the IGCT in the second main valve during the starting process being lower than the current change rate tolerance upper limit of the IGCT in the second main valve, and the main protection mechanism not being triggered.

6. The start-up control method of a DC system according to claim 4, characterized by, determining the DC current rise rate and the DC voltage rise rate according to the IGCT characteristic parameters of the first main valve, the IGCT characteristic parameters of the second main valve and the main protection mechanism comprises: constructing a preset mapping relationship, the preset mapping relationship representing the relationship between cause variables and result variables, the cause variables comprising the IGCT characteristic parameters of the first main valve, the IGCT characteristic parameters of the second main valve and the main protection mechanism, and the result variables comprising the DC current rise rate and the DC voltage rise rate; determining the current result variables according to the preset mapping relationship and current cause variables, the current cause variables comprising the IGCT characteristic parameters of the current first main valve, the IGCT characteristic parameters of the current second main valve and the current main protection mechanism, and the current result variables comprising the current DC current rise rate and the current DC voltage rise rate.

7. The start-up control method of a DC system according to claim 1, characterized by, the step of starting the first support valve and the second support valve comprises: in the case that the DC voltage of the first support valve and the second support valve is charged to a preset voltage, unlocking the first support valve and the second support valve; continuing to charge the first support valve and the second support valve until the DC voltage of the first support valve and the second support valve is charged to a rated voltage, determining that the starting of the first support valve and the second support valve is completed, and the preset voltage being lower than the rated voltage.

8. The start-up control method of a DC system according to claim 1, characterized by, controlling the first main valve by using a DC current to start the first main valve and controlling the second main valve by using a DC voltage to start the second main valve comprises: controlling the first main valve by using the DC current and applying a first PI control loop to start the first main valve; controlling the second main valve by using the DC voltage and applying a second PI control loop to start the second main valve.

9. A direct current system, characterized by comprises: A sending end and a receiving end, the sending end comprising a sending end converter valve, a sending end charging resistor and a transformer set, the receiving end comprising a receiving end converter valve and a receiving end charging resistor and a transformer set, the sending end converter valve comprising a first main valve and a first support valve, the receiving end converter valve comprising a second main valve and a second support valve, the first main valve and the second main valve being IGCT straight string valves and the IGCT straight string valves being three-phase twelve-bridge-arm IGCT straight string valves, the first support valve and the second support valve being two groups of three-phase full-bridge modules, any of the transformer sets comprising two star-delta connected transformers; A controller connected with the sending end and the receiving end respectively for executing the starting control method of the DC system according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that, The computer readable storage medium comprises a stored program, wherein the computer readable storage medium controls the device where the computer readable storage medium is located to execute the starting control method of the DC system according to any one of claims 1 to 8 when the program is running.

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