32 results about "High voltage direct current transmission" patented technology

The present application relates to the field of high-voltage direct current transmission, and aims to provide a topology of bridge arm integrated current-limiting energy-consuming device, a converter valve and a coordinated control method. The topology is a modular MMC architecture of three-phase double bridge arms, which comprises a plurality of MMC sub-modules connected in series in the upper bridge arm, and a current-limiting energy-consuming device composed of a plurality of current-limiting energy-consuming sub-modules connected in series in the lower bridge arm; the current-limiting energy-consuming sub-module comprises a sub-module main power unit and a sub-condition energy-consuming unit, the latter at least contains two energy-consuming units adapted to different fault conditions, and each contains an energy-consuming resistor and an adaptive condition switching device. The present application integrates the functions of direct-current fault current limiting and alternating-current fault energy consumption in the same integrated device, realizes integrated protection of AC and DC faults, does not need to configure multiple sets of separate equipment, and solves the problem of functional redundancy of the traditional scheme. Redundant configuration can be reduced, hardware cost is reduced, system size is reduced, and operation and maintenance complexity is simplified; the risk of device overvoltage breakdown is avoided, and the service life of the equipment is improved.

An energy supporting device for a high voltage direct current, HVDC, transmission system includes an energy supporting device for providing grid forming and / or virtual synchronous machine, VSM, capabilities to the HVDC transmission system. The energy supporting device comprises a plurality of cells configured to be connected to the HVDC transmission system, and a cell includes a full-bridge arrangement of power switches, an energy storage device electrically connected to the full-bridge arrangement, a resistor electrically connected between the plurality of cells and an electrical reference potential, and a bypass switch configured to allow the resistor to be bypassed. The energy supporting device is configured to be operated in a dissipation mode, in which the bypass switch is in an open state for allowing the resistor to dissipate electrical energy from the HVDC transmission system, and in which the energy storage devices of the plurality of cells are bypassed.

This application discloses a method and apparatus for optimizing the short-circuit impedance of converter transformers. The method includes: establishing the relationship between the cost of each transformer and its short-circuit impedance, the relationship between the loss discount of each transformer and its short-circuit impedance, and the relationship between the reactive power consumption of the converter valve and its short-circuit impedance; further determining the relationship between the number of reactive power compensation devices and the short-circuit impedance of the transformers, thereby determining the relationship between the cost of the reactive power compensation devices and the short-circuit impedance of the transformers; integrating these relationships to obtain a comprehensive cost function of the system cost with respect to the transformer short-circuit impedance; and determining the target short-circuit impedance value. It is evident that the comprehensive cost function considers the cost of the transformers, the loss discount, and the reactive power compensation devices. Therefore, in the design process of equipment in a high-voltage direct current transmission system, not only the cost of the transformers, but also the cost of losses and reactive power consumption are considered, and the determined target short-circuit impedance value is the most economical design value.

The present application relates to the technical field of high-voltage direct current transmission, and particularly relates to a non-blocking type direct current fault ride-through control method for a hybrid three-terminal direct current transmission system; comprising the following steps: S1, performing sub-module proportioning design on the hybrid three-terminal direct current transmission system; S2, performing fault detection and triggering, and when the triggering condition is met, performing S3; S3, performing hierarchical fault control strategy, including mode conversion of the LCC converter station and non-blocking control of the FHMMC converter station; S4, when the fault clearing condition is met, resetting the mode conversion of the LCC converter station and stopping the regulation of the DC current size of the FHMMC converter station by the current converter inhibitor. The technical problems of poor fault resistance and operation economy of the LCC-FHMMC hybrid three-terminal direct current transmission system are solved.

The application provides a capacitor-assisted off-grid commutation converter and a control method and device thereof and system, and relates to the technical field of high-voltage direct current transmission.The capacitor-assisted off-grid commutation converter provided by the application comprises a main circuit, at least one upper bridge arm circuit and at least one lower bridge arm circuit; an auxiliary circuit, at least one upper bridge transfer circuit, one upper bridge off-grid circuit, one upper bridge energy storage circuit, at least one upper bridge pumping circuit, at least one lower bridge transfer circuit, one lower bridge off-grid circuit, one lower bridge energy storage circuit and at least one lower bridge pumping circuit.The application can inhibit the occurrence of commutation failure and improve the reliability of high-voltage direct current transmission.

This invention provides a method, system, device, and medium for controlling the steady-state operating range of a modular multilevel converter (MMC). The method includes: using the maximum arm capacitor voltage within the acquired steady-state operating range of the MMC as a target capacitor peak voltage; setting the target capacitor peak voltage as a reference value; and controlling the steady-state operating range of the MMC based on preset operating constraints. This invention controls the expansion of the steady-state operating range of the MMC by employing a constant capacitor voltage peak method and preset operating constraints. This facilitates the accurate calculation and control of the steady-state operating range of the modular multilevel converter's high-voltage direct current transmission system, while maintaining the number of sub-modules and the cost of the MMC within the system.

A transmission / distribution system operation coordination-based HVDC operation system is provided, based on the operation of HVDC (High Voltage Direct Current) to expand supply stability, improve power quality, and enhance the economic efficiency of system operation throughout the domestic power system. The HVDC operation system is characterized by comprising: a power system management terminal that generates power system operation information; a plurality of HVDCs that generate HVDC availability information; a power market management server that generates power market operation information; distribution network operation information; a distribution system management computer that generates distribution network generation planning information and real-time distribution network generator operation information using distribution network generator bidding information and transmission system distribution network generation capacity acceptance information among the power market operation information; and an HVDC operation computer that generates HVDC operation planning information and distribution network generation capacity acceptance information based on the distribution network generation planning information, and generates real-time control information for controlling the operation of the HVDC based on the HVDC operation planning information, power system operation information, and distribution network operation information.

This application relates to the field of DC transmission protection technology, and particularly to a fault identification method for hybrid three-terminal high-voltage DC transmission lines based on the DC boundary voltage energy ratio and its application. By analyzing the boundary frequency characteristics of the DC line, rectifier side, and inverter side of the system, frequency characteristic curves of each boundary are obtained. Based on the frequency response characteristics of the overall system boundary frequency characteristic curve, highly distinguishable characteristic frequency bands are determined. When a fault occurs in the system, DC voltage signals at both ends of the rectifier / inverter side are acquired, and wavelet packet decomposition is performed on the acquired signals to extract the energy within the characteristic frequency bands. Based on the energy and characteristics of the two characteristic frequency bands, identification criteria for fault location and fault polarity are constructed. This enables rapid fault identification of hybrid three-terminal DC systems without the need for communication, thereby improving the safety and reliability of hybrid three-terminal high-voltage DC transmission lines. The aim is to solve the problem of fault type identification in hybrid three-terminal DC systems.

This invention discloses a fault pole selection method for double-circuit DC transmission lines on the same tower based on common-mode voltage integration, which is effective against inter-pole coupling. First, the voltage measured by the protection of the double-circuit common-mode four-pole line in the double-circuit DC transmission system is obtained. Then, based on the obtained four-pole voltage, the integral of the common-mode voltage change is calculated. Whether the integral exceeds the limit is determined to indicate a single-pole fault or an inter-pole fault. Finally, if a single-pole fault is determined, the specific fault pole is identified by comparing the sum of the common-mode voltage changes of circuit one and circuit two. This invention meets the requirements of high-voltage DC transmission systems for rapid protection. Simultaneously, this method exhibits high robustness against inter-pole inductive coupling and can more effectively avoid the influence of inter-pole electromagnetic coupling on the correct fault pole identification in DC transmission systems erected on the same tower, which is of great significance in ensuring the safe and stable operation of the power system.

The application provides a two-phase DC / DC converter with low-voltage side active filtering, and belongs to the technical field of power electronics and high-voltage direct current transmission. In the first phase unit, the anode of diode valve group one is connected with the anode of thyristor valve group one, the cathodes of diode valve group one and diode valve group two are connected with the high-voltage side port, the cathodes of thyristor valve group one and thyristor valve group two are grounded, and active bridge arms S1 are respectively connected with the midpoints of diode valve group one and thyristor valve group one; in the second phase unit, the anode of diode valve group two is connected with the anode of thyristor valve group two, and active bridge arms S2 are respectively connected with the midpoints of diode valve group two and thyristor valve group two; the anodes of diode valve group one, diode valve group two and one end of active bridge arm S0 are connected with the low-voltage side port, and the other end of active bridge arm S0 is grounded. The application has the advantages of low cost, small volume, high reliability, low loss, high control force of current by the active bridge arm, smooth current on the DC side, and no need of DC filter.

This invention discloses a method, system, and equipment for restarting a bipolar line in a high-voltage direct current (HVDC) transmission system after a fault. The method includes: each pole of the bipolar line in the HVDC transmission system detecting whether a fault has occurred in the DC line; when a fault is detected in one pole, deionization is controlled and a blocking restart signal is sent to the opposite pole; if the pole receives the blocking restart signal from the opposite pole within a time window, it is determined that the bipolar line is faulty; the pole to be blocked and restarted after the deionization time ends is determined based on the states of the two poles connected to the bipolar line. This invention, by adding a bipolar line fault detection function and improving the existing restart logic function, correctly identifies simultaneous faults in both bipolar DC lines. By using the DC line restart function to bypass the fault period, one pole performs restart while the other is directly blocked, reducing the impact of simultaneous bipolar blocking on the AC systems on both sides and improving the reliability of the power grid operation.

This invention provides an AC fault ride-through control device and method for wind power flexible DC grid-connected systems, belonging to the field of flexible DC transmission and new energy grid connection technology. Addressing the DC-side power redundancy and overvoltage issues caused by AC grid faults at the receiving end when wind power is connected to the grid via a modular multilevel converter (MWC) type HVDC transmission system, two control modes are proposed: First, when the DC voltage exceeds a preset threshold, the WFMMC initiates a step-down control; the energy storage system switches to a constant power control mode to adaptively absorb redundant power, and the wind turbine GSVSC maintains constant DC voltage control. Second, after the WFMMC initiates step-down control, the wind turbine GSVSC switches to a constant power control mode based on the grid connection point voltage deviation, and the energy storage system switches to a constant DC voltage control mode to absorb remaining power. This invention achieves redundant power storage, effectively suppresses DC voltage fluctuations, and improves the dynamic stability and operational reliability of the system during fault ride-through.

The application discloses a kind of direct current transmission system transient stability promotion method, device, equipment and medium, it is related to high voltage direct current transmission field, first according to the trigger lead angle and commutation overlap angle when LCC inverter is connected to grid, determine arc extinguishing angle, then based on the direct current value of inverter, equivalent commutation reactance and commutation overlap angle, the current amplitude of inverter is determined, and the power factor angle of inverter output port is determined by the current amplitude of alternating side, alternating side voltage effective value, equivalent commutation reactance, arc extinguishing angle and direct current value, finally based on direct current value, the capacitance value of inverter corresponding grid-connected compensation capacitor is determined by the direct current voltage value and power factor angle of inverter, to judge whether the direct current transmission system where inverter is located is stable according to capacitance value, i.e. for inverter direct current voltage power, the stability of inverter alternating side voltage is analyzed, the stability of entire direct current transmission system can be accurately detected, and the reliability of direct current transmission system is improved.

This application relates to the field of power system technology, specifically to a method and system for optimizing ultra-high voltage direct current (UHVDC) transmission technology based on variable weight optimization. The method includes: constructing multiple evaluation indicators covering three dimensions: power supply structure, stability level, and economic benefits; obtaining the actual values ​​of each evaluation indicator, standardizing the actual values ​​to obtain a standard state vector; dynamically weighting the key constraint indicators in the standard state vector based on a state-weighted penalty function to form a state-weighted vector; calculating a weighted composite vector by combining the initial weight vector and the state-weighted vector; performing a weighted summation of the standard state vector and the weighted composite vector to obtain a comprehensive score; and determining the recommended transmission technology route based on the preset interval of the comprehensive score. By constructing a scientific evaluation indicator system and introducing variable weight theory to dynamically adjust the indicator weights, the method effectively reflects the constraint effect of key indicators, improving the scientificity and accuracy of technology route selection.

The present specification relates to the technical field of power transmission, and discloses a photovoltaic high-voltage direct-current transmission method based on a current source type active commutation converter, to solve the problems of too high number of power conversion stages, too large power loss and low transmission efficiency of the current source type power transmission system in the existing power transmission system. The photovoltaic high-voltage direct-current transmission system of the current source type active commutation converter comprises, in sequence, a photovoltaic power supply module, a voltage boosting module, a high-voltage direct-current transmission module, a high-voltage active commutation module and a power transmission grid connection module; wherein the voltage boosting module comprises a low-voltage active commutation converter, a medium-frequency transformer and a high-voltage uncontrolled rectification bridge. The present application adopts a current source active commutation converter and a high-voltage uncontrolled rectification bridge on the low-voltage side, and can realize photovoltaic power generation maximum power tracking without an additional DC / DC converter, thereby reducing one level of power conversion, reducing switching loss, adopting an uncontrolled rectification bridge on the sending end high-voltage side, realizing unidirectional energy flow and reducing system cost.

This invention relates to a transient overvoltage suppression method for large-scale wind power transmission via ultra-high voltage direct current (UHVDC), belonging to the field of new energy grid-connected stability control technology. The method addresses the problem of transient overvoltage at the sending end caused by reactive power control delay of wind turbines after a DC fault. It divides the low-voltage ride-through process into three stages: voltage drop, recovery, and stabilization, and sets differentiated control objectives. The core of the method lies in establishing an equivalent circuit model of the sending-end system, analytically deriving the dynamic equation of the grid-connected voltage, calculating the optimal reactive current command and compensation amount in real time, and pre-adjusting reactive power injection during the voltage recovery stage to offset the impact of control delay. Simultaneously, a multi-dimensional intelligent switching criterion integrating voltage amplitude, rate of change, and system short-circuit ratio is constructed, enabling adaptive and precise start-up and graded exit of the control strategy. This invention effectively suppresses transient overvoltage, improves system stability, requires no additional hardware, and has strong engineering feasibility.

This invention discloses a topology and control method for a built-in flexible controllable converter transformer, belonging to the field of smart grid technology. Based on a traditional two-limb, three-winding converter transformer, it adds an independent voltage-regulating magnetic core and a matching voltage-regulating winding, as well as an energy-harvesting winding sharing a magnetic column with the grid-side winding, forming a three-limb, five-winding integrated transformer. A built-in back-to-back converter connects the energy-harvesting winding and the voltage-regulating winding, forming a power compensation channel with parallel energy harvesting and series voltage regulation. By real-time detection of grid-side voltage fluctuations, it dynamically calculates and injects a precisely controllable compensation voltage into the voltage-regulating winding, ensuring the stability of the voltage amplitude and phase on the valve side during grid-side voltage fluctuations. This invention achieves rapid, continuous, independent, and precise adjustment of voltage amplitude and phase within the transformer body, completely overcoming the technical bottlenecks of traditional mechanical tap changers—slow response, stepped adjustment, and inability to adjust phase—significantly improving the operational flexibility and voltage stability of high-voltage direct current transmission systems.

The present application relates to a kind of high voltage direct current transmission inverter side receiving end system small signal stability evaluation method, system, electronic equipment and computer readable storage medium, wherein method includes: gathering commutation bus steady-state operating parameter to construct inverter side nonlinear control equation group;Small disturbance response characteristics are extracted at system steady-state operating point, and linear equation group is established;Linear equation group is decoupled in combination with feedback control loop parameter, and aggregated to build transfer function admittance model;Based on the model, time-domain dynamic response curve is obtained, and the small signal stability evaluation index of system is output.The present application avoids complex electromagnetic transient modeling process, can intuitively, accurately reflect the time sequence dynamic characteristics of system under actual power grid fluctuation, greatly improve the efficiency of small signal stability analysis and evaluation of direct current transmission system.

The present application belongs to the technical field of high-voltage direct current (HVDC) transmission and relates to a method and a control device for restarting a high-voltage direct current (HVDC) transmission system in the event of a DC line fault. When a ground fault occurs in a DC line, the restart procedure comprises the following: In the first restart phase, the faulty DC pole is controlled for restart. If the required number of restarts is reached, but the restart is still unsuccessful, and the power command for both DC poles is greater than the maximum transmittable power of the non-faulty DC pole, the second restart phase comprises adjusting the power command for both DC poles to the maximum transmittable power of the non-faulty DC pole and controlling the faulty DC pole for restart.Controlling the faulty DC pole for restarting includes: controlling at least one voltage source converter at each of the two ends of the earth fault for continuous operation and determining the DC reference values ​​of the converters; based on the DC reference values ​​and within the decoupling time, controlling the DC current of the converters so that it is equal to or the difference is less than a first current threshold value, or the DC current of the converters is set to zero; increasing the DC voltage and / or the DC power of at least one converter within the restart time.

A direct current conversion device and system, relating to the technical field of high voltage direct current transmission. The direct current conversion device comprises a normally-on solid-state cir

This invention discloses a topology and control method for an externally mounted flexible controllable converter transformer, belonging to the field of smart grid technology. The topology includes a three-phase, three-winding power frequency converter transformer and a series-connected AC / AC power electronic module. Voltage regulation is achieved by externally mounting the series-connected AC / AC power electronic module at the low-voltage side terminal of the converter transformer's grid-side winding. This allows for the upgrading and transformation of existing converter transformers in HVDC transmission projects without significant modifications or replacements to the original converter transformer itself, demonstrating good engineering feasibility and economy. This invention possesses the ability to coordinate with reactive power compensation filter switching and converter valve control, improving upon the slow response, long adjustment step size, and difficulties in coordinated control of traditional converter units. While maintaining its advantages of large capacity and high reliability, it enhances the system's adaptability to grid disturbances and power command changes.

This application relates to a stability analysis method for high-voltage direct current (HVDC) transmission systems and a nonlinear modeling method, apparatus, and equipment for grid-connected converters. The nonlinear modeling method for grid-connected converters first determines voltage differential equations, voltage differential data, current differential equations, and current differential data by obtaining electrical quantity data. Then, it sequentially determines the main loop dynamic equations and periodic differential equations. By combining the voltage and current differential equations of the control loop dynamics with the main loop dynamic equations and periodic differential equations, a nonlinear differential equation for analyzing the stability of the HVDC transmission system is obtained. This nonlinear differential equation is used to analyze the stability of the HVDC transmission system, solving the problems of existing HVDC transmission systems based on modular multilevel converters where periodic time-varying dynamics and strongly nonlinear limiting behavior induce dynamic bifurcation leading to system instability, and the lack of a universal nonlinear mathematical model and efficient and accurate analysis method.

A method includes determining an operating mode of a hybrid electric propulsion system. The hybrid electric propulsion system includes a conditionally regulated high voltage direct current (HVDC) architecture. The conditionally regulated HVDC architecture includes a first switchable circuit formed between an HVDC bus, an HVDC electrical source, and a bi-directional direct current to direct current (DC-DC) converter configured to regulate electrical power flowing between the HVDC bus and the HVDC electrical source. The conditionally regulated HVDC architecture also includes a second switchable circuit formed between the HVDC bus and the HVDC electrical source. The method also includes configuring the conditionally regulated HVDC architecture based on the determined operating mode.

A transmission / distribution system operation coordination-based HVDC operation system is provided, based on the operation of HVDC (High Voltage Direct Current) to expand supply stability, improve power quality, and enhance the economic efficiency of system operation throughout the domestic power system. The HVDC operation system is characterized by comprising: a power system management terminal that generates power system operation information; a plurality of HVDCs that generate HVDC availability information; a power market management server that generates power market operation information; distribution network operation information; a distribution system management computer that generates distribution network generation planning information and real-time distribution network generator operation information using distribution network generator bidding information and transmission system distribution network generation capacity acceptance information among the power market operation information; and an HVDC operation computer that generates HVDC operation planning information and distribution network generation capacity acceptance information based on the distribution network generation planning information, and generates real-time control information for controlling the operation of the HVDC based on the HVDC operation planning information, power system operation information, and distribution network operation information.

This invention relates to a silicone rubber-based nonlinear conductive insulating composite material composition comprising at least one organopolysiloxane compound A, each molecule of which contains at least two alkenyl groups bonded to silicon atoms; at least one organohydrogen-based polysiloxane compound B; at least one catalyst C; optionally, at least one organosilicon resin D; at least one reinforcing filler E1; at least one conductive filler E2 and / or at least one semiconductor nanoparticle material E3; at least one organic conductive additive F; and optionally, at least one crosslinking inhibitor G. The invention also relates to a silicone rubber-based nonlinear conductive insulating composite material obtained by crosslinking and curing the composition; articles obtained from the composition or the composite material; and the use of the composition or the composite material in the preparation of cable accessories, particularly for high-voltage direct current transmission.

This application provides a harmonic elimination method and apparatus for modular multilevel converter high-voltage direct current (HVDC) transmission, comprising: constructing a current and voltage measurement matrix based on the topology and electrical parameters of an electromagnetic current transformer, its secondary system, an electromagnetic voltage transformer, and its secondary system in the HVDC transmission system; constructing an HVDC transmission impedance model including current and voltage measurement components based on the main circuit topology of the HVDC transmission system and the current and voltage measurement matrix; analyzing the HVDC transmission impedance model under preset operating conditions to obtain the impedance matrix of the current and voltage measurement components; and determining the resonant frequency of the HVDC transmission using the impedance matrix of the current and voltage measurement components to perform harmonic elimination. This application can analyze the mismatch effects caused by the measurement components of the current transformer (CT) and its secondary system, and the current transformer (PT) and its secondary system, respectively, determine the system resonant frequency, and eliminate the resonance effect.

A kind of offshore floating photovoltaic and coupled underwater hydrogen production system, the output end of photovoltaic power acquisition module is connected to DC bus, for obtaining original DC power, the input end of underwater electrolytic hydrogen production execution module is connected to DC bus by high-voltage DC transmission loop, the sensing signal output end of environmental perception monitoring module is connected to the input end of central control module, energy storage smoothing module is bidirectionally connected between DC bus and central control module, active power distribution logic unit is integrated in central control module, and power distribution logic unit is according to the real-time power data fed back by environmental perception monitoring module.The random photovoltaic energy captured by photovoltaic power acquisition module is exchanged with energy storage smoothing module on DC bus, the rapid throughput capacity of lithium battery energy storage unit electrochemical energy is utilized by using bidirectional DC-DC converter unit, to avoid the electrochemical corrosion and polarizing effect of fluctuating current on underwater electrolytic cell catalyst layer.

The application discloses a bridge arm reactor fault diagnosis method and device based on PINN-LSTM, equipment and medium, belongs to the field of power system equipment state monitoring. The method collects the bridge arm reactor package current voltage time series data through high-precision sensors, combines the geometric parameters of each turn in the package, and forms a fusion feature vector after preprocessing; a fault diagnosis model of fusion physical information neural network and long short-term memory network is constructed, and a supervised learning mechanism is introduced; according to the fault diagnosis model trained, the fault degree of the target bridge arm reactor is evaluated and analyzed, the electrical feature vector and the geometric feature vector are taken as inputs, and the fault diagnosis result and the accurate position of the fault turn in the package are output. The application solves the bottleneck of low fault diagnosis rate and the inability to locate the fault turn of the traditional method, is suitable for online fault monitoring of the bridge arm reactor in the high-voltage direct-current transmission system, and significantly improves the accuracy and reliability of fault diagnosis.

The application discloses a kind of considering lightning arrester parameter optimization's flexible direct current converter station insulation coordination design method, belong to high voltage direct current transmission and insulation coordination design technical field, adopt the method that electromagnetic transient simulation and statistical analysis are combined, by constructing the overvoltage statistical model and insulation resistance statistical model of key node of converter station, introduce statistical safety factor as insulation coordination evaluation index, and the economic cost of risk quantification is failed to insulation;Considering the residual voltage level of lightning arrester, energy level and arrangement position, establish the multi-objective optimization function model considering the deviation of statistical safety factor, insulation failure risk cost and lightning arrester cost;Using statistical safety feedback risk convergence iteration algorithm, the optimization function model is solved, to determine the insulation coordination of flexible direct current converter station, the present application can avoid the excessive dependence on experience margin of traditional design, realize lightning arrester parameter and insulation level collaborative optimization while the safe operation of flexible direct current converter station, reduce engineering investment and operation risk.