1852 results about "High voltage direct current transmission" patented technology

A high-voltage direct-current breaker is composed of an initial current path (1) and a fail current interdicting path (2). The initial current path (1) comprises at least one electric electronic switch module (3) and a mechanical switch (4), and the fail current interdicting path (2) comprises an initial capacitor (C) and a modular switching subunit series connection component (5). The modular switching subunit series connection component (5) is formed by connecting a plurality of sub units (6) in series. When a high-voltage direct-current electric transmission line fails, the opening and closing of a fail electric transmission line can be rapidly achieved.

The invention discloses a total bridge type MMC (Microsoft Management Console)-HVDC (High Voltage Direct Current Transmission) sub-module fault in-situ diagnosing and protecting method, belonging to the technical field of power transmission and distribution. According to the technical scheme, the method comprises the following steps: realizing fault in-situ diagnosis through an electric amount and a communication state of a monitoring sub-module, and transmitting a fault signal to a valve base controller (VBC); then locking a fault sub module through a sub module controller (SMC), and triggering a bypass fault sub module of a bypass device, so that the fault sub module and the system can be protected. The invention provides the total bridge type MMC-HVDC sub-module fault in-situ diagnosing and protecting method, which can be used for monitoring the state of the sub module in real time, and protect the system and the fault sub module after the sub module has a fault, and provides a method capable of keeping the system to stably operate when a signal transmission channel is caused by the fault of the superior controller of the communication fault or sub module controller (SMC).

The invention discloses a control method of an alternating voltage sensorless high voltage direct current transmission converter, belonging to the technical field of electrical equipment and comprising the following steps: establishing a stator resistor and an inductor for a virtual motor; building relative position relationships among a current vector, a voltage vector and a flux linkage vector, and analyzing a vectorgram; establishing a converter and flux linkage mathematic model, and calculating a virtual flux linkage vector of a system to obtain a power feedback quantity of the system; acquiring an active control signal and a reactive control signal of the system through a direct power control algorithm, and generating a PWM trigger converter for respectively and independently controlling the active power and reactive power of the system; and utilizing MATLAB simulation software to set up a system model for verifying, and obtaining a systematic selection device when the verification is successful. By utilizing Matlab/Simulink to set up a corresponding simulation model, the designed method is verified to have rapid response speed, the voltage and power after startup can still reach stable values after about 2 power frequency periods and have high steady state precision.

The present invention discloses an LCC and MMC series-connected HVDC system with DC fault ride-through capacity, comprising rectifier and inverter linked by DC transmission line; Both the positive pole and the negative pole of the rectifier and the inverter consist of line-commutated converter and modular converter in series-connection; the modular converter adopts one MMC or several parallel-connected MMCs. The present invention has the advantage of low cost, low power loss and high reliability of the LCC, as well as flexible control, low harmonics and AC voltage support of the MMC. Further, the present invention is able to deal with DC fault by itself, hence additional DC fault clearing equipment is not needed. As a result, the present invention is suitable for the field of long-distance large-capacity power transmission and has broad development potential.

The invention relates to a ground electrode circuit grounding protective system of a high-voltage DC transmission system. The system is provided with two parallel ground electrode circuits respectively connected in series with a high-voltage DC breaker, sets an allowable range of current differences of two ground wires and an allowable range of the subtraction of the line current sum of the two ground wires from the line current difference of the two ground wires and then sequentially executes the following control program: (1), reading currents of the two ground wires; (2), judging and comparing whether an absolute value of the current difference of two ground wires is larger than the allowable range thereof, if the absolute value is not larger than the allowable range, returning to the step (1); if the absolute value is larger than the allowable range, (3) then, judging whether the subtraction of the line current sum of the two ground wires from the line current difference of the two ground wires is smaller than or equal to the allowable range; if the subtraction is smaller than or equal to the allowable range, returning to the step (1); and if the subtraction is not smaller than or equal to the allowable range, enabling the high-voltage DC breaker which is connected in series with the ground wire with larger line current to trip and terminate the program. The system can avoid the imbalance of the ground electrode circuits due to the failures of the ground electrode circuits and protects the caused DC transmission system to be closed down.

The invention relates to a training examination system, in particular to a training examination system for technical staffs about operation and maintenance of a converter station of a high voltage direct current power transmission system. The intelligent training examination system of the high voltage direct current power transmission technology consists of a direct current power transmission simulation system, a database, a training examination system server, a router, a remote access server and an instructor subscriber terminal, and a plurality of local student subscriber terminals or a plurality of remote student subscriber terminals. The system can be adopted to undergo on-line learning, training and examination which comprises a theory training examination and a direct current power transmission system practical operation training examination, thereby automatically building the questions, timing, estimating scores and forming score reports based on the set question types and difficulties and meeting demands of normalized and intelligentized training and examination on primary workers, secondary workers and advanced workers for the operation and the maintenance of the direct current power transmission system.

The invention discloses a determination method of network side harmonic current of a high-voltage direct current power transmission system. The determination method comprises the following steps: if the harmonic current voltage at a direct current power transmission line inlet is zero, decoupling and equalizing a rectifying side and an inverting side into a plurality of independent six-pulse moving bridge units; dividing a work period of the six-pulse moving bridge units into six phase converting sections and six non-phase converting sections; calculating a phase converting overlapping angle of each phase converting section; equalizing a current converter into a harmonic current voltage source containing internal resistance; calculating the direct current side harmonic current according to the concrete forms of a smoothing reactor and a direct current filter; obtaining valve side harmonic current according to an equivalent circuit of the current converter; and converting the valve side harmonic current to a network side according to a connecting structure of a transformer to obtain the network side harmonic current. The invention considers background harmonic current and other nonideal factors, and can quickly and accurately obtain the harmonic current at the network side of a converter transformer, accelerate the period for designing an alternating current filter in the high-voltage direct current power transmission engineering and improve the design quality and the design efficiency.

A direct current to alternating current inverter sub-system is for a HVDC distribution system. The DC to AC inverter sub-system includes an enclosure and a DC to DC galvanically isolated buck converter having a DC input electrically connectable to a HVDC cable and a DC output. A DC to AC inverter includes a DC input electrically connected to the DC output of the DC to DC galvanically isolated buck converter and an AC output electrically connectable to an AC transmission line. The DC to AC inverter is mounted in an enclosure with the DC to DC galvanically isolated buck converter, in order that the DC output of the DC to DC galvanically isolated buck converter is directly electrically connected within the enclosure to the DC input of the DC to AC inverter.

The invention relates to a high-voltage capacitor imbalance protecting method for a high-voltage DC transmission system, comprising the following steps of: (1) analyzing imbalance current of a high-voltage capacitor in breakdown of a capacitor element during failure development in a high-voltage DC transmission system; (2) judging a symmetrical or dissymmetrical failure of the high-voltage capacitor in the high-voltage DC transmission system; and (3) proposing a corresponding setting principle and an action strategy aiming at the symmetrical or dissymmetrical failure. The high-voltage capacitor imbalance protecting method for a high-voltage DC transmission system has simple structure, convenience and practicability.

The invention relates to an ultra-high voltage direct current transmission line lightning stroke interference recognition method based on voltage relevancy and wavelet transformation transient state energy distribution characteristics, and belongs to the technical field of power system relay protection. When voltage of an ultra-high voltage direct current transmission line fluctuates, positive voltage and negative voltage of the initial 5ms are monitored; the relevancy between voltage of each electrode and voltage of each axis is calculated, and the lightning stroke interference is recognized according to the relevancy; the recognition of fault classifications is shifted to if the interference is caused by a fault; an additional component of line modal voltage is calculated, and seven dimension decomposition is performed on the additional component by utilizing a db3 wavelet; and the ratio of high frequency energy to low frequency energy is calculated, fault categories are distinguished, and fault protection is performed. According to the method, the signal acquisition time is short, the sample acquisition scale is small, and the voltage relevancy theory is used for recognizing lightning stroke interference and fault, so that the thought is clear, and the accuracy is high; the transient state energy distribution characteristics obtained through wavelet transformation are used for recognizing lightning stroke fault and short circuit fault, and the effect is obvious; and the method is easy to implement and is not easily influenced by system parameters and transition resistance.

The invention provides an audible noise calculating method for a high-voltage direct current electric transmission line of 4 to 8 bundle conducting wires and can effectively solve the audible noise prediction problem of an extra-high-voltage direct current electric transmission line. The calculating method comprises three parts that (1) the surface electric field intensity of the conducting of the high-voltage direct current electric transmission line is calculated; (2) the audible noise level (in summer) of the high-voltage direct current electric transmission line is calculated; and (3) the audible noise level of other seasons is obtained through adding or reducing correction items. The calculating method is simple, the implementation is easy, the audible noise of the direct current line corona of the 4 to 8 bundle conducting wires obtained through the calculation can be preferably coincided with the measuring results of testing line in China through being compared with calculation results of other formulas. The direct current corona audible noise of multiple conducting wires, obtained through calculation by the calculating method provided by the invention can more adapt to the environment climate condition in China. The audible noise calculating method is particularly suitable for the extra-high-voltage direct current corona audible noise calculation when during the 4 to 8 bundle conducting wire adoption in north China.

The invention relates to an extra-high-voltage DC power transmission line area internal and external fault identification method, and belongs to the technical field of high-voltage DC power transmission system relay protection. Fault current data are acquired firstly, current traveling wave direction is determined by comparing polarity of fault current at waveform mutation points, and then whether a fault signal comes from the outside of a rectification side area or the inside or the outside of an inversion side area is judged. A problem of double-end information interaction can be solved by adopting a single-end current transient protection method so that whole line protection is realized, and the method is used for distinguishing the fault outside the rectification side area, the fault inside the area and the fault outside the inversion side area.

The invention relates to a traveling wave analysis and recognition method for distinguishing lightning shielding failure from lightning counterattack of direct current transmission line. The lightning shielding failure of line is that lightning avoids the lightning shield line and directly strokes on the transmission line, while lightning counterattack of line is that lightning directly strokes on the lightning shield line or the tower. Because the earth resistance of tower exists, the potential on tower top suddenly increases and causes insulation flashover. The electromagnetic transient component generation mechanism of the high voltage direct current transmission line and the propagation path of lightning electromagnetic transient of the line in the lightning shielding failure are different from those in the lightning counterattack, the size and polarity of the initial surge voltage and the second surge voltage of the voltage transient signal exist significant difference. The traveling wave analysis and recognition method of the invention analyzes zero mode voltage using wavelet and distinguishes the lightning shielding failure and lightning counterattack failure according to the size and polarity of the initial surge voltage and the second surge voltage of the zero mode voltage in the traveling wave analysis and high-speed acquisition system of the protection zone. A lot of simulation results show that the method is reliable and effect. The physical concept of the invention is visible and clear, the method is easy to achieve and wide to use in the direct current system protector, also provides accurate initial data for researching lightning characteristics, analyzing lightning accident, discussing lightning protection countermeasure of transmission line and designing insulation coordination in the power system.

The invention discloses a high voltage direct current power transmission line protection method based on a voltage and current mutation direction. The method comprises the following steps that when a fault exists in a line area, the directions of the voltage mutation quantity and the current mutation quantity at the protection measurement of a rectifying side are opposite, and the directions of the voltage mutation quantity and the current mutation quantity at an inverter side are the same; the feature is also applicable for anode lines and cathode lines; and faults at other areas do not satisfy the condition. Thus, the protection criterion of the high voltage direct current transmission line is structured and the protection method is disclosed. As the method provided by the invention is adopted in the protection of the direct current transmission line, actions can be performed fast and accurately when fault lightning, high impedance earthing faults and pole-pole faults exist in the line area; no error action is carried out under the situations of lightning disturbance, faults outside the line protection area and the like; the protection method is simple and clear; the requirement on communication channels is not high; the requirements on data calculating speed and sampling frequency are low; no synchronizing processing is required for sampled data; and various operation ways of a bipolar direct current power transmission system are applicable, and the practical value is high.

The invention relates to a high voltage DC power transmission line shielding failure current waveform inversion recovery method. When the transmission line suffers the lightning stroke, the transient state traveling wave is spread and transmitted by the power transmission line, so the transient response at the protection installation place is different. The transmission line is equivalent to a natural lightning current air-termination system, and when the shielding failure happens, the prior traveling wave fault location technology can precisely locate the lightning stroke point; the parameters of the power transmission line can be obtained by measuring and analyzing on line; and with the transfer function of the transmission line deduced by the method, the lightning current waveform at the lightning stroke point can be finally obtained by carrying out the phase amplitude transformation, noise reduction, and Prony fit process, and deconvolution operation of on the transient voltage which is obtained through a high-speed collection at the protection installation place of the transmission line.

The invention relates to a method for identifying extra-high voltage direct current transmission line area inside and outside fault wavelet energy. The method comprises the following steps of: starting a starting element when a direct current fails and selecting bipolar direct current voltage data detected at a protection installation part after 5 ms of the fault, wherein the direct current voltage data are a discrete signal with sampling frequency of 100 kHz and sample sequence length of 500; finding out a direct current system line-mode voltage for four layers of wavelet decomposition by utilizing the bipolar direct current voltage so as to obtain low frequency coefficients and high frequency coefficients of the wavelet decomposition at different scales; and finding out wavelet high frequency energy from first scale to fourth scale and wavelet low frequency energy at the fourth scale according to the definition of wavelet energy of the signal at a certain scale, finding out the ratio of the wavelet high frequency energy to the wavelet low frequency energy, and comparing the size of the ratio of the wavelet high frequency energy to the wavelet low frequency energy so as to distinguish the inside faults and the outside faults. A large amount of simulation results show that the invention has good effect.

The invention relates to a high-voltage direct-current transmission detecting system and relative method, wherein it is formed by data collector, server and user terminal; the server comprises a forward data server, a real-time data server, a communication manage server and a history data server; the user terminal displays variable data information and supply graph detecting operation; he collector converts the collected analogue signal into digit signal, via network to be sent to the forward data server; the forward data server processes and calculates out relative signal value, and transmits the data to the real-time data server; the real-time data server stores the digit signal value, according to the request of user terminal, to send displayed data to relative user terminal, or transmit the user operation command via forward data server to the operator; the operator will control the executer to complete the operation; the server has stable and reliable operation; the user interface is friend, with simple operation.

The invention provides a compound type high-voltage direct current transmission system which comprises at least one rectifier station, a contravariant station and an aerial electric power transmission line. The rectifier station and the contravariant station both comprise positive electrodes and negative electrodes, a thyristor current converter is adopted in the rectifier station, a positive electrode and a negative electrode of the thyristor current converter both comprise at least one twelve-impulse thyristor current converter, a voltage source current converter which has direct current fault processing capacity is adopted in the contravariant station, and a positive electrode and a negative electrode of voltage source current converter both comprise at least one multi-level current converter with two series-wound modules. Connection points of the positive electrodes and negative electrodes of each station are connected with a grounding electrode or a local network according to operation mode, a double electrode ground return wire or a single ground return wire or a single electrode metal return wire, of the direct current transmission system. By means of the compound type high-voltage direct current transmission system, a commutation failure of the contravariant station in the direct current transmission system is avoided, operation mode is flexible, reliability is high, and project cost is reduced. Besides, the advantages of the thyristor current converter and the voltage source current converter are integrated, and thus the compound type high-voltage direct current transmission system has direct current side fault processing capacity.

The invention provides a method for high-voltage direct-current transmission commutation failure prevention. The method comprises the following steps that: whether commutation failure caused by alternating current-side faults occurs or not is judged; a commutation failure prevention system outputs rectangular wave commands to a control protection system; and rectangular waves are subtracted from trigger angle commands in the control protection system, and a thyristor is triggered in advance. With the method adopted, commutation failure can be prevented when grounding faults or interphase short-circuit faults occur on an alternating current system, and the reduction amplitude of direct-current voltage and power transmission can be lowered after the faults occur.