14 results about "Harmonic pollution" patented technology

The invention belongs to the field of intelligent power distribution systems, and provides a design method and system for an online harmonic monitoring system of a power system, and the method comprises the following steps: collecting a voltage signal of a transformer in a transformer substation in real time through a voltage transformer; performing frequency domain analysis on the acquired voltage signal by applying Fourier transform, and extracting each frequency component in the signal; setting a time window and a time interval, obtaining the frequency corresponding to the frequency component with the maximum amplitude in each time interval, and recording the frequency as the highest frequency; obtaining a harmonic super-harmonic frequency difference through the highest frequency, and obtaining a harmonic violent wave band time window through the harmonic super-harmonic frequency difference; and obtaining a harmonic violent band ratio through the harmonic violent band time window, and monitoring the operation condition of the power system through the harmonic violent band ratio. According to the design method provided by the embodiment of the invention, the problem can be quickly detected at the initial stage of harmonic pollution, and the harmonic filter is timely started or the load distribution is adjusted, so that the stability of the power system is ensured.

The utility model belongs to the technical field of electronics, and particularly relates to a low-harmonic rectification control circuit which remarkably counteracts low-order harmonics such as five-order harmonics and seven-order harmonics through multi-phase superposition of a phase-shifting transformer, the total harmonic distortion (THD) is lower than 5%, the environmental protection requirement of high-power industrial equipment for a power grid is met, and a control cable has the advantages of low harmonic pollution, low cost and the like. The DSP main control chip is combined with the digital timer, and the serial-to-parallel circuit only needs one PWM pin and three GPIO pins, so that the DSP resource occupation is reduced; the gating circuit adopts a general multiplexer (74HC4051D), so that the hardware complexity is reduced; the drive circuit realizes strong and weak current isolation through the isolation transformer, prevents high-voltage interference from damaging a control chip, improves the system safety, and reduces the maintenance cost of the circuit.

The invention discloses an electric energy metering error evaluation method, system, equipment and medium, and belongs to the technical field of power system energy storage equipment, and the method comprises the steps: collecting full-wave data of a power transmission and distribution line in a power grid, and carrying out the harmonic distribution analysis of the full-wave data, and obtaining a spatial-temporal characteristic parameter; according to the spatio-temporal characteristic parameters, performing multi-mode decomposition on the electric signals of the harmonic pollution area of the power grid by using a structure preserving algorithm; estimating the stochastic intensity of the cox process of each mode, and constructing an error response function in combination with the metering error parameters of the electric energy metering equipment; and performing quantitative evaluation on the error of the measurement result of the electric energy metering device by using the error response function. According to the method, the harmonic modal separation precision and efficiency are improved through an iterative optimization symplectic geometric modal decomposition algorithm, and high-precision input is provided for error evaluation; and an error response function is constructed in combination with stochastic intensity of the cox process, dynamic quantitative evaluation of the operation error of the electric energy metering equipment is realized, and the metering precision is improved.

The invention relates to the technical field of power electronics, and discloses a self-adaptive harmonic isolation method and device based on dynamic regulation and control of magnetic flux of a transformer, and the method comprises the steps: calculating the total harmonic distortion rate of a power grid to analyze the harmonic pollution level of the power grid, and calculating the harmonic distortion rate of the power grid according to the harmonic pollution level; generating a target magnetic flux compensation instruction for suppressing the dominant subharmonic corresponding to the power grid; inputting the target magnetic flux compensation instruction into a power converter connected with an auxiliary compensation winding in a preset harmonic isolation transformer to generate compensation harmonic magnetic flux of the target magnetic flux compensation instruction; the compensation harmonic magnetic flux is injected into the transformer iron core, the dominant sub-harmonics are offset, offset net magnetic flux is obtained, and a target magnetic flux compensation instruction and a magnetic flux error of the offset net magnetic flux are calculated; and when the magnetic flux error accords with a preset magnetic flux error threshold value, sine wave back electromotive force is generated in a main winding in the harmonic isolation transformer by utilizing the offset net magnetic flux so as to execute harmonic isolation. The isolation effect of harmonic propagation can be improved.

The present application belongs to the technical field of power system, and particularly relates to a method, device, equipment and medium for reconstruction planning of a small-area power distribution network. The method is based on the structure of the small-area power distribution network and load characteristics, and performs electrical characteristic analysis and harmonic pollution prediction, and then simulates power quality, maps harmonic distribution and system performance. The harmonic propagation is analyzed through state simulation, a dynamic model for harmonic suppression is established, and control parameters are adjusted in real time to optimize power quality. A multi-level feedback control system is constructed, power supply reliability is predicted, and integrated optimization technology is used to improve the network structure. In combination with the power flow path diagram and the optimized network structure, the power supply parameters are aligned, and finally an optimized power distribution network reconstruction scheme is formulated, aiming to improve power supply quality and reliability.

The invention discloses a harmonic wave treatment method for an LNG dual-fuel ship, and belongs to the technical field of crossing of ship engineering and power electronics. According to the method, the active power filter is introduced into the ship power system, the situation of lack of ship harmonic suppression is thoroughly changed, the crossing of passive tolerance and active control is realized, the technical system of the ship power system is perfected, and the industrial technology development is promoted to a new step. The total harmonic distortion rate of the power grid can be accurately controlled, it is ensured that the total harmonic distortion rate is stably controlled within 5%, and the strict standard requirements of IEC 6100-3-6 and the like are completely met. Meanwhile, a power filter in the waste gas treatment system solves the problem of harmonic waves generated by an SOX supply pump frequency converter in a desulfurization treatment device. By inhibiting generation and propagation of harmonic waves from the source, the problem of harmonic wave pollution troubling a ship power system for a long time is effectively solved, and a solid guarantee is provided for stable operation of ship electrical equipment.

The present application belongs to the technical field of low-voltage reactive power compensation. A method for identifying harmonic risk and inhibiting misoperation of an intelligent metal comprehensive distribution box is disclosed. First, the present application collects harmonic-related operating state information and constructs a harmonic risk feature vector. Then, a light gradient boosting classification model is used to estimate the basic risk probability of future short-term harmonic risk. Next, the harmonic level is corrected at the combination level according to the basic risk probability and the current total harmonic distortion rate, combined with the equivalent compensation capacity of the candidate compensation combination, to generate a set of allowed branches. Finally, the comprehensive control cost is calculated in the allowed set, and the combination with the minimum cost is selected to execute the switching. The present application jointly uses the future harmonic risk probability, the candidate combination harmonic level estimate, the zero sequence current, the branch health state and the compensation capacity for switching decision, which can effectively reduce the number of harmonic over-limit windows and the number of misoperation actions, and can balance the inhibition effect and compensation performance under harmonic pollution conditions.

The invention discloses a harmonic suppression method and system under a high background harmonic condition, and the method comprises the steps: carrying out the wavelet transformation of an input power grid voltage signal, and extracting the amplitude information of each harmonic in real time; dynamically determining a target harmonic set which needs to be suppressed at present through a preset threshold judgment mechanism according to the extracted amplitude information of each harmonic; for each harmonic in the target harmonic set, synchronously executing harmonic suppression and phase compensation operation; sending the signal subjected to harmonic suppression and phase compensation into a phase-locked loop to obtain a power grid synchronous phase; the system provided by the invention comprises an extraction module, a determination module, a compensation module and a suppression module, and provides a highly purified input signal for the phase-locked loop, so that the phase-locked loop can still maintain rapid and overshoot-free high-precision phase locking under serious harmonic pollution; and the operation stability and the electric energy quality of the grid-connected inverter in a complex power grid environment are remarkably improved.

The invention discloses an ice-melting rectifier transformer with high overload resistance and harmonic suppression, and relates to the technical field of transformers. The oil tank comprises an oil tank body, and an iron core in the oil tank body is of a stepping stacked structure and a 45-degree full-inclined seam and is fastened through a clamping piece module. Three coil assemblies and a grounding electric shielding layer are arranged on the core column, each coil assembly comprises an upper winding and a lower winding, oxygen-free copper wires smaller than or equal to 2 mm are adopted to be matched with the K transposition technology, and supporting blocks are arranged between the adjacent wires to form oil channels. The grounding electric shielding layer is composed of a copper foil shielding plate and a connecting plate and is grounded. The oil tank and the air cooler form a circulating heat dissipation system through an oil way and an oil pump. Through cooperation of multiple structures, magnetic resistance and loss are reduced, structural stability is improved, efficient heat dissipation is achieved, harmonic pollution is suppressed, overload resistance and short circuit resistance are enhanced, the requirement for direct-current ice melting is met, and safe operation of a power grid in winter is guaranteed.

This invention belongs to the field of converter control technology, specifically disclosing a converter grid-connected harmonic suppression method and system based on the TD3 algorithm and instantaneous reactive power theory, including the following steps: acquiring three-phase current signals; and obtaining observed state variables from the three-phase current signals based on instantaneous reactive power theory and the TD3 algorithm. S t ; Observe the state quantity S t Input the trained TD3 agent and obtain action values. a t ; For action values a t Coordinate transformation and SVPWM processing are performed to obtain a modulation signal; the modulation signal is then applied to the grid-connected converter. This invention has the advantages of high dynamic response speed, wide harmonic suppression bandwidth, and strong adaptability, and can effectively solve the dynamic suppression problem of harmonic pollution in new energy grid-connected scenarios.

The invention provides a three-phase power supply tail end protection method and system based on hydrogen-harmonic linkage, and relates to the technical field of power system safety protection, and the method comprises the steps: synchronously collecting the concentration of hydrogen released by cable insulation, cable temperature and harmonic current data; performing digital filtering and feature extraction on the collected data to obtain a hydrogen concentration mean value, a temperature rise peak value and a harmonic average current; calculating a dynamic risk index through a multi-parameter fusion risk model; triggering and executing a corresponding grading protection response according to the dynamic risk index; and the change conditions of the hydrogen concentration, the cable temperature and the harmonic current after the graded protection response is executed are monitored in real time, and a subsequent protection strategy is dynamically adjusted. According to the invention, through hydrogen-harmonic wave-temperature multi-parameter fusion sensing and frequency spectrum division cooperative treatment, on the premise of no power failure, accurate advanced early warning of cable insulation early degradation and efficient suppression of harmonic wave pollution are realized, and the problems of early warning lag, low treatment efficiency and measure separation can be solved.

The application relates to the technical field of power quality optimization of power distribution networks, and discloses a power quality optimization method and system for a power distribution network with distributed energy access, which comprises the following steps: collecting distributed energy output and power grid node voltage data in real time, quantifying the incoordination state of the system by calculating fluctuation rate and dispersion; performing preliminary time sequence coordination of multiple units based on the state to determine the output time sequence; obtaining node estimated voltage and evaluating harmonic level by using power flow calculation to trigger the amplitude optimization process; constructing an optimization model with the aim of inhibiting harmonics and stabilizing voltage, fitting the nonlinear relationship between output and voltage / harmonics, generating a constraint set and solving to obtain the final output amplitude sequence; integrating the time sequence and the amplitude sequence to generate a collaborative control instruction. The application effectively suppresses voltage fluctuation and harmonic pollution, and improves the power quality and operation stability of the power distribution network with high-proportion distributed energy access.

The application discloses a high-overload-resistance and harmonic-suppression ice-melting rectifier transformer, and relates to the technical field of transformers. The high-overload-resistance and harmonic-suppression ice-melting rectifier transformer comprises an oil tank, the iron core in the oil tank adopts a step-by-step stacking structure and a 45-degree full-inclined joint, and is fastened through a clamping piece module; three coil assemblies and a grounding electric shielding layer are arranged on a core column, the coil assembly comprises upper and lower windings, adopts a <2mm oxygen-free copper wire matched with a K transposition process, and a supporting block is arranged between adjacent wires to form an oil channel; the grounding electric shielding layer is composed of a copper foil shielding plate and a connecting plate and is grounded; and the oil tank forms a circulating heat dissipation system through an oil circuit, an oil pump and an air cooler. Through cooperation of multiple structures, the high-overload-resistance and harmonic-suppression ice-melting rectifier transformer reduces magnetic resistance and loss, improves structural stability, realizes efficient heat dissipation, suppresses harmonic pollution, enhances the anti-overload and anti-short-circuit capability, meets the demand of direct-current ice melting, and guarantees safe operation of a power grid in winter.

The application belongs to the field of intelligent power distribution systems, and provides a design method and system for an online harmonic monitoring system of a power system, which comprises the following steps: collecting voltage signals of transformers in a substation in real time through a voltage transformer; performing frequency domain analysis on the collected voltage signals by applying Fourier transform, and extracting each frequency component in the signals; setting a time window and a time interval, obtaining a frequency corresponding to a frequency component with the largest amplitude in each time interval, and recording the frequency as a highest frequency; obtaining a harmonic super-harmonic frequency difference through the highest frequency, and obtaining a harmonic severe wave band time window through the harmonic super-harmonic frequency difference; obtaining a harmonic severe wave band ratio through the harmonic severe wave band time window, and monitoring the operation of the power system through the harmonic severe wave band ratio. According to the design method of the embodiment of the application, problems can be quickly detected in the early stage of harmonic pollution, and a harmonic filter can be started or load distribution can be adjusted in time, so that the stability of the power system is ensured.