Starting method and system of land new energy and low-frequency sending-out system

Abstract

The invention provides a land new energy and low frequency sending system starting method and system, and the method comprises the steps: closing a power frequency circuit breaker, carrying out the uncontrolled charging of a power frequency side of a converter valve, and detecting whether the power frequency voltage of the power frequency side reaches a voltage threshold value or not; when the power frequency voltage reaches a voltage threshold value, starting a power frequency side control system, carrying out controllable charging on the power frequency side, and detecting a capacitor voltage value when the power frequency side is subjected to controllable charging; when the capacitor voltage value reaches the minimum value, the bypass circuit breaker is closed, and then the capacitor voltage value of the power frequency side is detected; when the re-detected capacitor voltage value reaches a rated value, a low-frequency side control system is started, controllable charging is conducted on the low-frequency side, an alternating-current voltage value of the low-frequency side is detected, and when the alternating-current voltage value reaches a set value, a low-frequency circuit breaker and a low-frequency new energy switching station are closed, and a low-frequency new energy power generation field is started; according to the invention, land new energy and a low-frequency output system are adopted to output energy in a low-frequency form, so that the fluctuation of new energy can be dealt with, and the reliability of remote grid connection is enhanced.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, and in particular to a method and system for starting a land-based new energy and low-frequency transmission system. Background Art

[0002] At present, the onshore new energy is sent out through low-frequency transmission technology, which has the advantages of greater transmission capacity and distance than industrial frequency AC, is also convenient for networking, and has strong applicability. In recent years, it has received more and more attention. In order to achieve the dual carbon goals, large-scale onshore new energy has gradually been developed and utilized;

[0003] However, due to geographical factors, the distance to grid connection for onshore renewable energy is relatively long. The conventional industrial frequency AC grid connection has poor stability and low transmission capacity, while the use of DC faces the problem of poor networking flexibility. Summary of the invention

[0004] In order to solve the problem of poor grid connection stability caused by long transmission distance when conventional industrial frequency AC is used for grid connection of onshore renewable energy in the prior art, the present invention proposes a method for starting an onshore renewable energy and a low-frequency transmission system, comprising:

[0005] The onshore renewable energy and low-frequency transmission system comprises a low-frequency renewable energy power plant, a low-frequency renewable energy interconnection module, a low-frequency circuit breaker, a frequency conversion station, a power frequency starting resistor, a bypass circuit breaker, a power frequency circuit breaker and a power frequency power grid connected in sequence;

[0006] The method for starting the onshore new energy and low-frequency transmission system comprises:

[0007] The system startup process starts, the power frequency circuit breaker is closed, and the power frequency current generated by the power frequency grid passes through the power frequency starting resistor to charge the power frequency side of the converter valve in the frequency conversion station until the capacitor voltage value when the power frequency side of the converter valve is charged reaches a set minimum value;

[0008] The bypass circuit breaker is closed, and the capacitor voltage value on the power frequency side of the converter valve is detected again. When the capacitor voltage value on the power frequency side of the converter valve detected again reaches the rated value, the low frequency side of the converter valve is controlledly charged by starting the low frequency side control system of the frequency conversion station until the AC voltage value on the low frequency side of the converter valve reaches the set value;

[0009] By closing the low-frequency circuit breaker and the low-frequency new energy interconnection module, starting the low-frequency new energy power plant;

[0010] Among them, the power frequency starting resistor and the bypass circuit breaker are connected in parallel, and the initial states of the low-frequency new energy interconnection module, the low-frequency circuit breaker, the power frequency circuit breaker and the bypass circuit breaker are all disconnected.

[0011] Optionally, the power frequency current generated by the power frequency grid passes through the power frequency starting resistor to charge the power frequency side of the converter valve in the frequency conversion station until the capacitor voltage value when the power frequency side of the converter valve is charged reaches a set minimum value, including:

[0012] The power frequency current is generated by the power frequency grid and passes through the power frequency starting resistor to perform uncontrolled charging on the power frequency side of the converter valve in the frequency conversion station until the power frequency voltage on the power frequency side of the converter valve reaches the voltage threshold;

[0013] By starting the power frequency side control system of the frequency conversion station, the power frequency side of the converter valve is controllably charged until the capacitor voltage value when the power frequency side of the converter valve is controllably charged reaches a set minimum value.

[0014] Optionally, the controlling the charging of the power frequency side of the converter valve by starting the power frequency side control system of the frequency conversion station includes:

[0015] By starting the power frequency side control system of the frequency conversion station, using a proportional integral controller to output a power frequency reference voltage;

[0016] Based on the power frequency reference voltage, the power frequency side of the converter valve is controllably charged.

[0017] Optionally, the method of outputting a power frequency reference voltage by using a proportional-integral controller includes:

[0018] Using a proportional-integral controller, a power frequency current reference value is generated;

[0019] Outputting a power frequency reference voltage according to the power frequency current reference value;

[0020] Wherein, the power frequency current reference value includes: a power frequency d-axis current reference value and a power frequency q-axis current reference value.

[0021] Optionally, the controlling of charging the low-frequency side of the converter valve by starting the low-frequency side control system of the frequency conversion station includes:

[0022] By starting the low-frequency side control system of the frequency conversion station, a proportional-integral controller is used to output a low-frequency reference voltage;

[0023] Based on the low-frequency reference voltage, the low-frequency side of the converter valve is controllably charged.

[0024] Optionally, the method of using a proportional-integral controller to output a low-frequency reference voltage includes:

[0025] Using a proportional-integral controller, a low-frequency current reference value is generated;

[0026] Outputting a low-frequency reference voltage according to the low-frequency current reference value;

[0027] The low-frequency current reference value includes a low-frequency d-axis current reference value and a low-frequency q-axis current reference value.

[0028] Optionally, the onshore new energy and the low-frequency new energy interconnection module in the low-frequency transmission system includes: a low-frequency new energy switch station and a low-frequency overhead line.

[0029] Based on the same inventive concept, the present invention also provides a starting system for a land-based new energy and low-frequency transmission system, comprising:

[0030] The power frequency side charging module is used to close the power frequency circuit breaker at the beginning of the system startup process, generate a power frequency current through the power frequency grid and pass through the power frequency starting resistor to charge the power frequency side of the converter valve in the frequency conversion station until the capacitor voltage value when the power frequency side of the converter valve is charged reaches a set minimum value;

[0031] A low-frequency side charging module is used to close the bypass circuit breaker and detect the capacitor voltage value on the power frequency side of the converter valve again. When the capacitor voltage value on the power frequency side of the converter valve detected again reaches a rated value, the low-frequency side of the converter valve is controllably charged by starting the low-frequency side control system of the frequency conversion station until the AC voltage value on the low-frequency side of the converter valve reaches a set value;

[0032] A power plant starting module, used to start the low-frequency new energy power plant by closing the low-frequency circuit breaker and the low-frequency new energy interconnection module;

[0033] Among them, the power frequency starting resistor and the bypass circuit breaker are connected in parallel, and the initial states of the low-frequency new energy interconnection module, the low-frequency circuit breaker, the power frequency circuit breaker and the bypass circuit breaker are all disconnected.

[0034] Optionally, the power frequency side charging module includes:

[0035] an uncontrolled charging submodule, configured to generate an industrial frequency current through the industrial frequency power grid and pass through the industrial frequency starting resistor to perform uncontrolled charging on the industrial frequency side of the converter valve in the frequency conversion station until the industrial frequency voltage on the industrial frequency side of the converter valve reaches the voltage threshold;

[0036] The controllable charging submodule is used to controllably charge the power frequency side of the converter valve by starting the power frequency side control system of the frequency conversion station until the capacitor voltage value during controllably charging the power frequency side of the converter valve reaches a set minimum value.

[0037] Optionally, the controllable charging submodule includes:

[0038] A reference voltage output unit, used to output a power frequency reference voltage by starting the power frequency side control system of the frequency conversion station and using a proportional integral controller;

[0039] The power frequency controllable charging unit is used to controllably charge the power frequency side of the converter valve based on the power frequency reference voltage.

[0040] Optionally, the reference voltage output unit includes:

[0041] The power frequency current generating subunit is used to generate a power frequency current reference value by using a proportional integral controller;

[0042] A power frequency voltage output subunit, used for outputting a power frequency reference voltage according to the power frequency current reference value;

[0043] Wherein, the power frequency current reference value includes: a power frequency d-axis current reference value and a power frequency q-axis current reference value.

[0044] Optionally, the low-frequency side charging module includes:

[0045] A voltage reference output submodule, used to output a low-frequency reference voltage by starting the low-frequency side control system of the frequency conversion station and using a proportional-integral controller;

[0046] The low-frequency controllable charging submodule is used to controllably charge the low-frequency side of the converter valve based on the low-frequency reference voltage.

[0047] Optionally, the voltage reference output submodule includes:

[0048] A low-frequency current generating unit, used for generating a low-frequency current reference value by using a proportional-integral controller;

[0049] A low-frequency voltage output unit, used for outputting a low-frequency reference voltage according to the low-frequency current reference value;

[0050] The low-frequency current reference value includes a low-frequency d-axis current reference value and a low-frequency q-axis current reference value.

[0051] Optionally, the onshore new energy and the low-frequency new energy interconnection module in the low-frequency transmission system includes: a low-frequency new energy switch station and a low-frequency overhead line.

[0052] In another aspect, the present invention further provides an electronic device, comprising: at least one processor and a memory; the memory and the processor are connected via a bus;

[0053] The memory is used to store one or more programs;

[0054] When the one or more programs are executed by the at least one processor, a method for starting a land-based new energy and low-frequency transmission system as described above is implemented.

[0055] On the other hand, the present invention further provides a computer-readable storage medium having an execution program stored thereon, and when the execution program is executed, a method for starting a land-based new energy and low-frequency transmission system as described above is implemented.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] The present invention provides a method and system for starting an onshore renewable energy and low-frequency transmission system, comprising: at the beginning of the system startup process, closing the power frequency circuit breaker, performing uncontrolled charging on the power frequency side of the converter valve in the frequency conversion station, and detecting whether the power frequency voltage on the power frequency side of the converter valve reaches a set voltage threshold; when the power frequency voltage on the power frequency side of the converter valve reaches the voltage threshold, starting the power frequency side control system of the frequency conversion station, performing controllable charging on the power frequency side of the converter valve, and detecting the capacitor voltage value when the power frequency side of the converter valve is controllably charged; when the capacitor voltage value reaches a set minimum value, closing the bypass circuit breaker, and detecting the capacitor voltage value on the power frequency side of the converter valve again; when the capacitor voltage value on the power frequency side of the converter valve detected again reaches a rated value, starting the frequency conversion station The low-frequency side control system of the station performs controllable charging on the low-frequency side of the converter valve, and detects the AC voltage value on the low-frequency side of the converter valve. When the AC voltage value reaches the set value, the low-frequency circuit breaker and the low-frequency new energy switch station are closed to start the low-frequency new energy power plant; the present application ensures the safe grid connection of low-frequency new energy and the stability of system operation by starting the onshore new energy and low-frequency delivery system in stages. Through the parallel connection of the power frequency starting resistor and the bypass circuit breaker, the impact of the power frequency current on the converter valve is effectively limited in the initial stage, and the stable charging of the power frequency side capacitor is achieved, which lays the foundation for subsequent low-frequency control; the bypass circuit breaker and the low-frequency control system are gradually closed, and the precise operation of the low-frequency circuit breaker and the new energy interconnection module is combined to enable the low-frequency new energy power plant to start safely and be efficiently connected to the grid. Therefore, the method of the present invention effectively avoids voltage fluctuations and startup shocks through precise charging control and step-by-step operation, improves the reliability, stability and new energy access efficiency of the system, and provides a safe and reliable solution for large-scale access of low-frequency new energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 A schematic flow chart of a method for starting a land-based new energy and low-frequency transmission system provided by the present invention;

[0059] Figure 2A schematic diagram of the framework composition of an onshore renewable energy and low-frequency transmission system in a method for starting the onshore renewable energy and low-frequency transmission system provided by the present invention;

[0060] Figure 3 A schematic diagram of a specific structure of an onshore renewable energy and low-frequency transmission system in a method for starting an onshore renewable energy and low-frequency transmission system provided by the present invention;

[0061] Figure 4 A schematic diagram of the structural composition of a starting system for a land-based new energy and low-frequency transmission system provided by the present invention;

[0062] Figure 5 The present invention provides a schematic structural diagram of an electronic device. DETAILED DESCRIPTION

[0063] The present invention proposes a method, system, device and medium for starting a new energy and low-frequency transmission system on land. The specific implementation methods of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0064] Embodiment 1:

[0065] The present invention provides a method for starting a land-based new energy and low-frequency transmission system, the flow chart of which is as follows: Figure 1 As shown, including:

[0066] Step 1: The system startup process begins, the power frequency circuit breaker is closed, and the power frequency current generated by the power frequency grid passes through the power frequency starting resistor to charge the power frequency side of the converter valve in the frequency conversion station until the capacitor voltage value when the power frequency side of the converter valve is charged reaches the set minimum value;

[0067] Step 2: close the bypass circuit breaker and detect the capacitor voltage value on the power frequency side of the converter valve again. When the capacitor voltage value on the power frequency side of the converter valve detected again reaches the rated value, start the low frequency side control system of the frequency conversion station to controllably charge the low frequency side of the converter valve until the AC voltage value on the low frequency side of the converter valve reaches the set value.

[0068] Step 3: Start the low-frequency renewable energy power plant by closing the low-frequency circuit breaker and the low-frequency renewable energy interconnection module;

[0069] With the rapid development of new energy, especially the widespread application of low-frequency new energy such as onshore wind power and solar energy, how to efficiently and stably integrate these new energy into the power grid and ensure the safe startup of onshore new energy and low-frequency transmission systems has become an important technical challenge. Traditional access methods for power grids and new energy mostly rely on high-frequency power grids or complex control systems. However, with the continuous advancement of low-frequency power grids and conversion technologies, the demand for the adaptation of low-frequency new energy and power grids is increasing. In order to solve this problem, the present invention proposes a method for starting an onshore new energy and low-frequency transmission system, which ensures the smooth startup of each component of the system through precise step control and intelligent voltage regulation mechanism. Specifically:

[0070] In one implementation, the process of generating a power frequency current through the power frequency grid and passing through a power frequency starting resistor in the above step 1 to charge the power frequency side of the converter valve in the frequency conversion station until the capacitor voltage value when the power frequency side of the converter valve is charged reaches a set minimum value may include:

[0071] The power frequency current is generated by the power frequency grid and passes through the power frequency starting resistor to charge the power frequency side of the converter valve in the frequency conversion station without control until the power frequency voltage on the power frequency side of the converter valve reaches the voltage threshold;

[0072] By starting the power frequency side control system of the frequency conversion station, the power frequency side of the converter valve is controllably charged until the capacitor voltage value when the power frequency side of the converter valve is controllably charged reaches a set minimum value;

[0073] In this implementation, by dividing the power frequency side charging process of the converter valve into two stages: uncontrolled charging and controlled charging, a more accurate and flexible voltage regulation method is provided. This staged charging method can not only effectively control the capacitor voltage increase process of the converter valve, avoiding damage to the equipment caused by too fast or too slow voltage changes, but also improve the system startup efficiency and stability to a certain extent. In the uncontrolled charging stage, the power frequency current generated by the power frequency grid is charged through the power frequency starting resistor, which can safely increase the voltage to the power frequency voltage threshold, laying the foundation for subsequent controlled charging. At this time, the voltage change does not need to be precisely regulated. The main purpose is to provide a stable initial voltage for the power frequency side of the converter valve. When entering the controllable charging stage, the power frequency side control system of the frequency conversion station is started to precisely regulate the converter valve so that the capacitor voltage value reaches the set minimum value to ensure that the converter valve can be further operated after the voltage reaches the safety standard. Through this design, the system can provide more precise voltage regulation at different stages, making the startup process of the converter valve smoother and more reliable, reducing the impact on the equipment, and improving the operating safety and efficiency of the frequency conversion station and the entire power grid system, thereby achieving a more efficient and stable startup process.

[0074] After completing the initial power frequency uncontrolled charging and making the power frequency side voltage of the converter valve reach the voltage threshold, the system enters the precise control stage. At this time, in order to ensure that the power frequency side capacitor voltage of the converter valve can be steadily and accurately increased to the set minimum value, the power frequency side control system of the frequency conversion station is started to control the voltage. By introducing the power frequency side control system, the system can use a more precise adjustment mechanism for charging, thereby avoiding excessive or insufficient voltage fluctuations, and ensuring that the capacitor voltage of the converter valve gradually reaches the predetermined value within a stable and safe range. Specifically:

[0075] In one implementation, the process of controlling the power frequency side of the converter valve by starting the power frequency side control system of the frequency conversion station may include:

[0076] By starting the power frequency side control system of the frequency conversion station and using the proportional integral controller, the power frequency reference voltage is output;

[0077] Based on the power frequency reference voltage, the power frequency side of the converter valve is controlled to be charged;

[0078] In this implementation, by starting the power frequency side control system of the frequency conversion station and using the proportional integral controller (PID controller) to output the power frequency reference voltage, the controllable charging of the power frequency side of the converter valve can be realized, which can significantly improve the voltage regulation accuracy and stability during the startup process of the frequency conversion station. The traditional charging process may face the risk of voltage fluctuation or excessive increase, and this implementation introduces the PID control strategy to make the charging process more stable, accurate and controllable. The proportional integral controller adjusts the output current in real time according to the error between the actual voltage and the reference voltage, thereby ensuring that the capacitor voltage of the converter valve increases steadily at a predetermined rate, avoiding overshoot or hysteresis, and improving the response speed and stability of the system. This design process combines intelligent control methods to ensure that the voltage range of the equipment during the startup process meets safety standards through precise voltage control, while maximizing the efficiency of the startup process; in addition, the introduction of the PID controller can not only finely adjust the voltage changes during the charging process, but also effectively avoid the risk of overcharging or undercharging, thereby improving the reliability and adaptability of the frequency conversion station. Therefore, through this implementation method, this solution based on precise adjustment of the control system makes the entire startup process more controllable, reduces the impact on the equipment, and provides a safer and more efficient technical path for complex low-frequency renewable energy access to the power grid.

[0079] In the process of controlling the charging of the converter valve by starting the power frequency side control system of the frequency conversion station, it is crucial to ensure accurate voltage regulation. The realization of this accurate regulation depends on the accurate calculation of the current reference value. In this process, the proportional integral controller not only directly outputs the power frequency reference voltage, but also needs to generate the power frequency current reference value through calculation as the basis of the output voltage. Specifically:

[0080] In one implementation, the process of outputting the industrial frequency reference voltage by using a proportional-integral controller may include:

[0081] Using a proportional-integral controller, a power frequency current reference value is generated;

[0082] According to the power frequency current reference value, output the power frequency reference voltage;

[0083] The power frequency current reference value includes: a power frequency d-axis current reference value and a power frequency q-axis current reference value;

[0084] In this implementation, by using a proportional-integral controller to generate a power frequency current reference value and outputting a power frequency reference voltage based on these reference values, the accuracy and flexibility of voltage regulation can be significantly improved. Traditional voltage control methods may face large fluctuations and hysteresis, while this implementation ensures that the output of the power frequency voltage is more stable and accurate by first calculating the precise current reference value, especially the power frequency d-axis current reference value and the power frequency q-axis current reference value. The proportional-integral controller dynamically adjusts the voltage output according to the change of current, making the voltage rise and fall process smoother and avoiding voltage overshoot or instability. This control method can not only improve the response speed of the system, but also optimize the charging process of the converter valve, ensure the stable growth of the capacitor voltage, and thus improve the startup efficiency and safety of the frequency conversion station.

[0085] By using a proportional-integral controller to generate a power frequency current reference value and outputting a power frequency reference voltage based on these reference values, the system can accurately adjust the relationship between voltage and current, and provide a stable power input for the charging process of the converter valve. This fine conversion mechanism of current to voltage ensures the smoothness and response speed of the system operation. However, the stability of the power grid does not only rely on the control of the power frequency side, but the charging process on the low-frequency side is also critical. Therefore, after the charging on the power frequency side is completed and reaches the set voltage standard, the system needs to turn to the low-frequency side, start the low-frequency side control system of the frequency conversion station, and continue to controllably charge the converter valve. Specifically:

[0086] In one implementation, the process of controlling the low-frequency side of the converter valve by starting the low-frequency side control system of the frequency conversion station may include:

[0087] By starting the low-frequency side control system of the frequency conversion station and using a proportional-integral controller, a low-frequency reference voltage is output;

[0088] Based on the low-frequency reference voltage, the low-frequency side of the converter valve is controlled to be charged;

[0089] In this implementation, by starting the low-frequency side control system of the frequency conversion station and using the proportional-integral controller to output the low-frequency reference voltage for controllable charging, the accuracy and stability of the low-frequency side charging process can be significantly improved. The traditional low-frequency charging control method may face the problem of voltage fluctuation or untimely response, while this implementation adopts the proportional-integral control strategy to accurately adjust the low-frequency reference voltage and charge based on this voltage to ensure that the capacitor voltage is steadily increased to the set value; the proportional-integral controller automatically adjusts the voltage output according to the real-time error, which can avoid overcharging or undercharging, making the charging process on the low-frequency side safer and more reliable. This implementation not only optimizes the charging process on the low-frequency side and reduces the potential risks caused by voltage instability, but also provides a more accurate voltage control method for the stable operation of the entire frequency conversion station. Through fine control of the low-frequency side, the system can adapt to different load changes and grid conditions, and improve the safety and efficiency of low-frequency new energy grid connection; at the same time, this implementation can ensure that the frequency conversion station can smoothly transition under multiple frequency conditions, reduce the impact of frequent adjustments on equipment, and enhance the robustness and flexibility of the system.

[0090] In this implementation, the process of outputting a low-frequency reference voltage by using a proportional-integral controller may include:

[0091] Using a proportional-integral controller, a low-frequency current reference value is generated;

[0092] According to the low-frequency current reference value, a low-frequency reference voltage is output;

[0093] Among them, the low-frequency current reference value includes a low-frequency d-axis current reference value and a low-frequency q-axis current reference value; in this implementation, by using a proportional-integral controller to generate a low-frequency current reference value and outputting a low-frequency reference voltage according to these reference values, the accuracy and dynamic response capability of the low-frequency charging process can be significantly improved. Different from the traditional charging method, this implementation provides a more accurate voltage regulation basis by first calculating the low-frequency current reference value, especially the low-frequency d-axis current reference value and the low-frequency q-axis current reference value; the proportional-integral controller adjusts the low-frequency reference voltage in real time according to the change of the current reference value to ensure that the charging process remains stable and accurate under different operating conditions. In this way, the voltage regulation on the low-frequency side no longer depends solely on the voltage error, but optimizes the control strategy through real-time feedback of the current, thereby avoiding voltage fluctuations and overcharging. The control method in this implementation not only improves the stability of low-frequency charging, but also greatly improves the adaptability and reliability of the frequency conversion station in a variable power grid environment. By finely adjusting the low-frequency current reference value, the system can achieve more flexible voltage regulation to ensure a smooth and safe charging process on the low-frequency side.

[0094] In the above step 2, the capacitor voltage value on the power frequency side of the converter valve is detected again by closing the bypass circuit breaker. When the capacitor voltage value on the power frequency side of the converter valve detected again reaches the rated value, the low-frequency side control system of the frequency conversion station is started to controllably charge the low-frequency side of the converter valve until the AC voltage value on the low-frequency side of the converter valve reaches the set value, so as to achieve a smooth transition from the power frequency side to the low-frequency side of the frequency conversion station, and ensure that the converter valve can gradually and safely reach a stable working state during the entire startup process. Specifically, closing the bypass circuit breaker and detecting the capacitor voltage value on the power frequency side of the converter valve again until it reaches the rated value means that the system first fully charges the power frequency side of the converter valve through the power frequency power grid to ensure that its capacitor voltage is in a controllable state, thereby laying the foundation for subsequent low-frequency side charging. By starting the low-frequency side control system and controlling the charging of the low-frequency side when the capacitor voltage reaches the set rated value, the system can achieve a smooth transition from industrial frequency to low frequency. This approach enables the charging process on the low-frequency side to gradually introduce low-frequency voltage for regulation after the industrial frequency voltage reaches stability, thus avoiding voltage mutations or instability and reducing the risk of damage to the converter valve. At the same time, by gradually increasing the low-frequency voltage to the set value, it can ensure that the converter valve can operate stably under an ideal working environment, minimizing the startup impact of the system.

[0095] In the above step 3, after the low-frequency new energy power plant is started by closing the low-frequency circuit breaker and the low-frequency new energy interconnection module, the low-frequency new energy power plant is effectively connected to the frequency conversion station and the industrial frequency power grid, thereby realizing the grid-connected output of new energy. The closing of the low-frequency circuit breaker and the low-frequency new energy interconnection module indicates that the physical connection between the low-frequency new energy power plant and the frequency conversion station has been established, and electricity can be smoothly transmitted from the low-frequency power plant to the frequency conversion station, and further sent to the industrial frequency power grid. Therefore, the onshore new energy and low-frequency transmission system is safely started.

[0096] In one implementation, Figure 2 As shown, the above-mentioned onshore renewable energy and low-frequency transmission system may include a low-frequency renewable energy power plant, a low-frequency renewable energy interconnection module, a low-frequency circuit breaker, a frequency conversion station, a power frequency starting resistor, a bypass circuit breaker, a power frequency circuit breaker and a power frequency power grid connected in sequence; wherein the power frequency starting resistor and the bypass circuit breaker are connected in parallel, and the initial states of the low-frequency renewable energy interconnection module, the low-frequency circuit breaker, the power frequency circuit breaker and the bypass circuit breaker are all disconnected;

[0097] In this implementation, the parallel connection design of the above-mentioned power frequency starting resistor and bypass circuit breaker enables the power frequency starting resistor to effectively limit the current and protect the equipment from the impact of sudden current in the initial startup stage, while the bypass circuit breaker can quickly close after the power frequency side capacitor voltage of the converter valve reaches the set value, bypassing the starting resistor, reducing energy loss and improving the startup efficiency; the initial disconnection state of the low-frequency new energy interconnection module, low-frequency circuit breaker, power frequency circuit breaker and bypass circuit breaker is to ensure that the system startup is gradually promoted in a predetermined order. The disconnection state avoids the early access of low-frequency equipment when the capacitor voltage has not reached the set value, prevents system instability or misoperation, and ensures that the power frequency side and low-frequency side voltages of the converter valve increase steadily according to the predetermined trajectory, thereby achieving safe grid access. Only when the system parameters are stable and meet the predetermined conditions, the relevant circuit breakers will be closed to start the low-frequency new energy power plant, thereby ensuring the safe, reliable and efficient startup of the entire onshore new energy and low-frequency transmission system.

[0098] In this implementation, the above-mentioned onshore low-frequency new energy power plant is connected through one end of the low-frequency new energy interconnection module, and the other end of the low-frequency new energy interconnection module is connected to the low-frequency side of the frequency conversion station through a low-frequency circuit breaker. The power frequency side of the frequency conversion station is connected to the power frequency starting resistor and its bypass circuit breaker, and the power frequency starting resistor and its bypass circuit breaker are connected to the power frequency power grid through the power frequency circuit breaker; In this implementation, the low-frequency new energy power plant is connected to the low-frequency side of the frequency conversion station through the low-frequency new energy interconnection module, ensuring that the power of the low-frequency new energy can be effectively input into the frequency conversion station and converted into electric energy suitable for the power grid through the frequency conversion station. The role of the low-frequency new energy interconnection module is to regulate the low-frequency current and voltage, provide a stable power transmission channel, and prevent the power grid from being affected by unstable power fluctuations; the closure of the low-frequency circuit breaker ensures the safe transmission and control of power. Once the system abnormality is detected, the power supply can be cut off in time to ensure the safety of the system; secondly, the power frequency starting resistor and the bypass circuit breaker are connected to the power frequency power grid, and are connected to the low-frequency new energy system through the power frequency circuit breaker, which plays a role in effectively starting the frequency conversion station. The power frequency grid provides preliminary power frequency current during the system startup process. This process realizes current regulation through the power frequency starting resistor to ensure that the charging process of the converter valve capacitor of the frequency conversion station does not produce overshoot or instability. The setting of the bypass circuit breaker provides a flexible electrical switching function for the system, which can optimize the flow of electric energy under different conditions and prevent overload or failure of electrical equipment. Through this multi-level linkage design, the system can ensure a smooth transition between low-frequency and power frequency power. The power of the low-frequency new energy power plant enters the frequency conversion station through the low-frequency new energy interconnection module and is converted into power suitable for the power grid. At the same time, the role of the power frequency starting resistor and the bypass circuit breaker enables the system to start the frequency conversion station with the support of the power frequency grid and prepare for the subsequent access of low-frequency new energy. The reasonable connection of all these devices ensures the efficiency, stability and safety of power transmission.

[0099] In this implementation, the low-frequency new energy interconnection module in the above-mentioned onshore new energy and low-frequency transmission system may include a low-frequency new energy switch station and a low-frequency overhead line. The specific architecture diagram of the corresponding onshore new energy and low-frequency transmission system may be as follows: Figure 3 shown.

[0100] In summary, the present invention is aimed at the problem of poor grid connection stability caused by long transmission distance when conventional industrial frequency AC is usually used for grid connection of onshore new energy in the prior art. A method for starting onshore new energy and low-frequency transmission system is proposed, and accurate control steps are used to ensure that low-frequency new energy can be smoothly connected to the grid and operate stably. The startup process starts with closing the industrial frequency circuit breaker. The industrial frequency power grid generates current through the industrial frequency starting resistor to charge the industrial frequency side of the converter valve of the frequency conversion station until the capacitor voltage of the converter valve reaches the set minimum value. This initial stage ensures that the industrial frequency side capacitor of the converter valve is properly charged, so that the frequency conversion station can enter the subsequent low-frequency control stage. When the industrial frequency capacitor voltage reaches a predetermined value, the bypass circuit breaker is closed, and the system will detect the industrial frequency capacitor voltage value of the converter valve again. As the voltage stabilizes, the control system on the low-frequency side is started, and the AC voltage on the low-frequency side of the converter valve is further stabilized at the set value through controllable charging on the low-frequency side. After the voltage on the low-frequency side is stable, the low-frequency circuit breaker and the low-frequency new energy interconnection module are closed, and the low-frequency new energy power plant is officially started, completing the grid connection process of the new energy. During the entire startup process, the power frequency starting resistor and the bypass circuit breaker are connected in parallel to ensure the smooth charging of the power frequency current, while reducing the impact on the converter valve capacitor, and avoiding damage to the equipment due to overcurrent or voltage fluctuations. The present invention makes the connection between the low-frequency new energy and the power grid more stable and reliable through phased and refined control, avoiding voltage shocks or system instability problems that may occur during direct startup; especially in the process of connecting low-frequency new energy, through reasonable voltage control and gradual charging, not only the service life of the equipment is improved, but also the safety and stability of the power grid are guaranteed. Ultimately, this design can effectively promote the large-scale grid connection of new energy, and provide technical support for promoting the widespread application of green energy and the intelligent construction of power grids.

[0101] Embodiment 2:

[0102] Based on the same inventive concept, the present invention also provides a starting system for a land-based new energy and low-frequency transmission system, the structural composition diagram of which is shown in FIG. Figure 4 As shown, including:

[0103] The power frequency side charging module is used to close the power frequency circuit breaker at the beginning of the system startup process, generate power frequency current through the power frequency grid and pass through the power frequency starting resistor to charge the power frequency side of the converter valve in the frequency conversion station until the capacitor voltage value when the power frequency side of the converter valve is charged reaches the set minimum value;

[0104] The low-frequency side charging module is used to close the bypass circuit breaker and detect the capacitor voltage value on the power frequency side of the converter valve again. When the capacitor voltage value on the power frequency side of the converter valve detected again reaches the rated value, the low-frequency side of the converter valve is controlledly charged by starting the low-frequency side control system of the frequency conversion station until the AC voltage value on the low-frequency side of the converter valve reaches the set value;

[0105] The power plant start-up module is used to start the low-frequency renewable energy power plant by closing the low-frequency circuit breaker and the low-frequency renewable energy interconnection module;

[0106] Among them, the power frequency starting resistor and the bypass circuit breaker are connected in parallel, and the initial states of the low-frequency new energy interconnection module, the low-frequency circuit breaker, the power frequency circuit breaker and the bypass circuit breaker are all disconnected.

[0107] In one implementation, the above-mentioned power frequency side charging module may include:

[0108] The uncontrolled charging submodule is used to generate power frequency current through the power frequency grid and pass through the power frequency starting resistor to perform uncontrolled charging on the power frequency side of the converter valve in the frequency conversion station until the power frequency voltage on the power frequency side of the converter valve reaches a voltage threshold;

[0109] The controllable charging submodule is used to controllably charge the power frequency side of the converter valve by starting the power frequency side control system of the frequency conversion station until the capacitor voltage value during controllably charging the power frequency side of the converter valve reaches a set minimum value.

[0110] In one implementation, the controllable charging submodule may include:

[0111] A reference voltage output unit is used to output a power frequency reference voltage by starting the power frequency side control system of the frequency conversion station and using a proportional integral controller;

[0112] The power frequency controllable charging unit is used to controllably charge the power frequency side of the converter valve based on the power frequency reference voltage.

[0113] In one implementation, the reference voltage output unit may include:

[0114] The power frequency current generating subunit is used to generate a power frequency current reference value by using a proportional integral controller;

[0115] The power frequency voltage output subunit is used to output a power frequency reference voltage according to a power frequency current reference value;

[0116] The power frequency current reference value includes: a power frequency d-axis current reference value and a power frequency q-axis current reference value.

[0117] In one implementation, the low-frequency side charging module may include:

[0118] The voltage reference output submodule is used to output a low-frequency reference voltage by starting the low-frequency side control system of the frequency conversion station and using a proportional-integral controller;

[0119] The low-frequency controllable charging submodule is used to controllably charge the low-frequency side of the converter valve based on the low-frequency reference voltage.

[0120] In this implementation, the voltage reference output submodule may include:

[0121] A low-frequency current generating unit, used for generating a low-frequency current reference value by using a proportional-integral controller;

[0122] A low-frequency voltage output unit, used for outputting a low-frequency reference voltage according to a low-frequency current reference value;

[0123] The low-frequency current reference value includes a low-frequency d-axis current reference value and a low-frequency q-axis current reference value.

[0124] In one implementation, the above-mentioned onshore new energy and low-frequency new energy interconnection module in the low-frequency transmission system may include a low-frequency new energy switch station and a low-frequency overhead line.

[0125] Embodiment 3:

[0126] like Figure 5 As shown, the present invention also provides an electronic device, which may be a computer device, a single-chip device, an intelligent mobile device, etc. The electronic device in this embodiment may include a processor, a memory, a transceiver component, etc. The memory, the processor, and the transceiver component are connected via a bus; the memory may be used to store an execution program, and an exemplary execution program may include instructions; the processor is used to execute the instructions stored in the memory. The memory may also be used to store data, which may be called and / or modified when the instructions are executed.

[0127] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, and is specifically suitable for loading and executing one or more instructions in a storage medium to implement a corresponding method flow or a corresponding function, so as to implement the steps of a method for starting a land-based new energy and low-frequency transmission system in the above-mentioned embodiment.

[0128] Embodiment 4:

[0129] Based on the same inventive concept, the present invention also provides a readable storage medium, specifically an electronic device readable storage medium (Memory), which is a memory device in an electronic device for storing programs and data. It can be understood that the storage medium here can include both built-in storage media in electronic devices and, of course, extended storage media supported by electronic devices. The storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by a processor are also stored in the storage space, and these instructions can be one or more execution programs (including program codes). It should be noted that the storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor loads and executes one or more instructions stored in the storage medium, which can implement the steps of a method for starting a land-based new energy and low-frequency transmission system in the above-mentioned embodiment.

[0130] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0131] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0132] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0133] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the application, but these changes, modifications or equivalent substitutions are all within the protection scope of the claims to be approved.

Claims

1. A method for starting a land-based new energy and low-frequency transmission system, characterized in that: The onshore renewable energy and low-frequency transmission system comprises a low-frequency renewable energy power plant, a low-frequency renewable energy interconnection module, a low-frequency circuit breaker, a frequency conversion station, a power frequency starting resistor, a bypass circuit breaker, a power frequency circuit breaker and a power frequency power grid connected in sequence; The method for starting the onshore new energy and low-frequency transmission system comprises: The system startup process starts, the power frequency circuit breaker is closed, and the power frequency current generated by the power frequency grid passes through the power frequency starting resistor to charge the power frequency side of the converter valve in the frequency conversion station until the capacitor voltage value when the power frequency side of the converter valve is charged reaches a set minimum value; The bypass circuit breaker is closed, and the capacitor voltage value on the power frequency side of the converter valve is detected again. When the capacitor voltage value on the power frequency side of the converter valve detected again reaches the rated value, the low frequency side of the converter valve is controlledly charged by starting the low frequency side control system of the frequency conversion station until the AC voltage value on the low frequency side of the converter valve reaches the set value; By closing the low-frequency circuit breaker and the low-frequency new energy interconnection module, starting the low-frequency new energy power plant; Among them, the power frequency starting resistor and the bypass circuit breaker are connected in parallel, and the initial states of the low-frequency new energy interconnection module, the low-frequency circuit breaker, the power frequency circuit breaker and the bypass circuit breaker are all disconnected.

2. The method according to claim 1, characterized in that The power frequency current generated by the power frequency grid passes through the power frequency starting resistor to charge the power frequency side of the converter valve in the frequency conversion station until the capacitor voltage value when the power frequency side of the converter valve is charged reaches a set minimum value, including: The power frequency current is generated by the power frequency grid and passes through the power frequency starting resistor to perform uncontrolled charging on the power frequency side of the converter valve in the frequency conversion station until the power frequency voltage on the power frequency side of the converter valve reaches the voltage threshold; By starting the power frequency side control system of the frequency conversion station, the power frequency side of the converter valve is controllably charged until the capacitor voltage value when the power frequency side of the converter valve is controllably charged reaches a set minimum value.

3. The method according to claim 2, characterized in that The method of controlling the power frequency side of the converter valve by starting the power frequency side control system of the frequency conversion station includes: By starting the power frequency side control system of the frequency conversion station, using a proportional integral controller to output a power frequency reference voltage; Based on the power frequency reference voltage, the power frequency side of the converter valve is controllably charged.

4. The method according to claim 3, characterized in that The method of using a proportional-integral controller to output a power frequency reference voltage comprises: Using a proportional-integral controller, a power frequency current reference value is generated; Outputting a power frequency reference voltage according to the power frequency current reference value; Wherein, the power frequency current reference value includes: a power frequency d-axis current reference value and a power frequency q-axis current reference value.

5. The method according to claim 1, characterized in that The method of controlling the low-frequency side of the converter valve by starting the low-frequency side control system of the frequency conversion station includes: By starting the low-frequency side control system of the frequency conversion station, a proportional-integral controller is used to output a low-frequency reference voltage; Based on the low-frequency reference voltage, the low-frequency side of the converter valve is controllably charged.

6. The method according to claim 5, characterized in that The method of using a proportional-integral controller to output a low-frequency reference voltage comprises: Using a proportional-integral controller, a low-frequency current reference value is generated; Outputting a low-frequency reference voltage according to the low-frequency current reference value; The low-frequency current reference value includes a low-frequency d-axis current reference value and a low-frequency q-axis current reference value.

7. The method according to claim 1, characterized in that The low-frequency new energy interconnection module in the onshore new energy and low-frequency transmission system includes: a low-frequency new energy switch station and a low-frequency overhead line.

8. A starting system for a new energy and low-frequency transmission system on land, characterized in that: include: The power frequency side charging module is used to close the power frequency circuit breaker at the beginning of the system startup process, generate a power frequency current through the power frequency grid and pass through the power frequency starting resistor to charge the power frequency side of the converter valve in the frequency conversion station until the capacitor voltage value when the power frequency side of the converter valve is charged reaches a set minimum value; A low-frequency side charging module is used to close the bypass circuit breaker and detect the capacitor voltage value on the power frequency side of the converter valve again. When the capacitor voltage value on the power frequency side of the converter valve detected again reaches a rated value, the low-frequency side of the converter valve is controllably charged by starting the low-frequency side control system of the frequency conversion station until the AC voltage value on the low-frequency side of the converter valve reaches a set value; A power plant starting module, used to start the low-frequency new energy power plant by closing the low-frequency circuit breaker and the low-frequency new energy interconnection module; Among them, the power frequency starting resistor and the bypass circuit breaker are connected in parallel, and the initial states of the low-frequency new energy interconnection module, the low-frequency circuit breaker, the power frequency circuit breaker and the bypass circuit breaker are all disconnected.

9. The starting system according to claim 8, characterized in that: The power frequency side charging module comprises: an uncontrolled charging submodule, configured to generate an industrial frequency current through the industrial frequency power grid and pass through the industrial frequency starting resistor to perform uncontrolled charging on the industrial frequency side of the converter valve in the frequency conversion station until the industrial frequency voltage on the industrial frequency side of the converter valve reaches the voltage threshold; The controllable charging submodule is used to controllably charge the power frequency side of the converter valve by starting the power frequency side control system of the frequency conversion station until the capacitor voltage value during controllably charging the power frequency side of the converter valve reaches a set minimum value.

10. The starting system according to claim 9, characterized in that: The controllable charging submodule comprises: A reference voltage output unit, used to output a power frequency reference voltage by starting the power frequency side control system of the frequency conversion station and using a proportional integral controller; The power frequency controllable charging unit is used to controllably charge the power frequency side of the converter valve based on the power frequency reference voltage.

11. The starting system according to claim 10, characterized in that: The reference voltage output unit comprises: The power frequency current generating subunit is used to generate a power frequency current reference value by using a proportional integral controller; A power frequency voltage output subunit, used for outputting a power frequency reference voltage according to the power frequency current reference value; Wherein, the power frequency current reference value includes: a power frequency d-axis current reference value and a power frequency q-axis current reference value.

12. The starting system according to claim 8, characterized in that: The low-frequency side charging module comprises: A voltage reference output submodule, used to output a low-frequency reference voltage by starting the low-frequency side control system of the frequency conversion station and using a proportional-integral controller; The low-frequency controllable charging submodule is used to controllably charge the low-frequency side of the converter valve based on the low-frequency reference voltage.

13. The starting system according to claim 12, characterized in that: The voltage reference output submodule comprises: A low-frequency current generating unit, used for generating a low-frequency current reference value by using a proportional-integral controller; A low-frequency voltage output unit, used for outputting a low-frequency reference voltage according to the low-frequency current reference value; The low-frequency current reference value includes a low-frequency d-axis current reference value and a low-frequency q-axis current reference value.

14. An electronic device, characterized in that: include: at least one processor and memory; The memory and the processor are connected via a bus; The memory is used to store one or more programs; When the one or more programs are executed by the at least one processor, a method for starting a land-based new energy and low-frequency transmission system as described in any one of claims 1 to 7 is implemented.

15. A computing device readable storage medium, characterized in that: An execution program is stored thereon, and when the execution program is executed, a method for starting a land-based new energy and low-frequency transmission system as described in any one of claims 1 to 7 is implemented.

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