35results about How to "Solving Harmonic Problems" patented technology

The invention dsiclsoes a microgrid system with an asymmetric non-linear load and a power balancing control method. The system comprises a plurality of DG units connected in parallel and line impedors connected with all DG units. The line impedors are connected to a microgrid bus by PCC points. A three-phase balancing resistive load, an asymmetric linear load, and a diode rectifier non-linear load of a load unit are connected to the microgrid bus by PCC points. A measurement module for measuring voltage fundamental wave positive sequence and negative sequence components and harmonic wave components of the PCC points is also connected to the microgrid bus. The microgrid bus is connected with a 10-kV main power grid by a static switch and a transformer successively. According to the invention, reactive and harmonic power balancing of the microgrid is realized by using a selective virtual impedance based on the virtual fundamental positive and negative sequence impedance and the virtual variable harmonic impedance; a harmonic and unbalancing voltage compensation controller enables equal division of an unbalanced power and a harmonic power to be realized; and a problem of unbalancing of the harmonic wave and the voltage of the microgrid can be solved.

The invention discloses an interconnection detection cloud platform facing electric vehicle charging facilities. The platform is used for a charging facility network access detection, engineering acceptance detection, a business expansion operation detection, a transportation and maintenance detection, compatibility and consistency tests of charging facilities and an electric vehicle and the like;the cloud platform is composed of a detection management center, a knowledge expert database, a data analysis center and a service data interface, and are used for providing support of a detection standard, equipment state analysis, fault analysis and the like for on-site detection personnel, and providing technical support for an industry management equipment platform account, an electric vehicle characteristic library, a charging equipment detection library, a charging equipment fault library, a detection method and the detection standard, and providing professional charging facility detection statistic analysis reports for the national power grid, the government, charging operators and suppliers, and providing a device fault detection report and a diagnosis report interface for the charging operators.

The invention relates to a DC supply mode of an LED street lamp and belongs to the field of low-voltage power supply and distribution. A DC power supply system comprises a DC power station composed of a street lamp transformer (1), a rectifier filter (2) and a reactive power compensator (3), a DC transmission line, an LED street lamp driving power supply (4) and the like. With the advancement of the LED light source technology, the service life of the light source exceeds 50, 000 hours, the consumption of electric energy is lower than one half of that of a conventional light source, the LED street lamp technology gradually comes into practice, and the LED light source is more and more widely used; the working mode of the conventional LED street lamp is as follows: each lamp is provided with a driving power supply for converting alternating current into direct current, so that the LED light source emits light; the single-phase rectifier, the filter capacitor and the PFC (power factor correction) circuit in the power supply are the bottleneck of popularization and application of the LED street lamp due to shorter service life besides harmonic pollution; and to fully exert the advantages of the LED light source with energy conservation and long service life, the invention provides a solution for DC supply mode of the LED street lamp, electric energy is provided for the LED street lamp by the DC supply mode, and the rectifier bridge, the filter capacitor and the PFC circuit in the conventional power supply are saved, so that the purpose of long-term secure and reliable operation of the LED street lamp is achieved.

The invention provides an alternating current signal effective value measuring device which comprises an absolute value conversion circuit, a high-frequency triangular wave generation circuit, a PWM signal modulation circuit, a front-end integral circuit, a rear-end integral circuit, a reset circuit, a sampling maintaining circuit, a dividing circuit, a root circuit and a timing circuit. According to the alternating current signal effective value measuring device, the absolute value | v(t)/of signals to be tested v(t) and single-polarity symmetric high-frequency triangular wave signal v(t) are subjected to modulation, and high-frequency PWM signals far higher than the v(t) frequency are obtained; due to the fact that v(t) are continuous signals, and vc(t) frequency is far higher than v(t), the area of the PWM signals in each cycle is equal to the area formed by the| v(t)/in the corresponding PWM signal cycle; meanwhile, v(t)<2> is also a continuous function, so that the effective value of v(t) can be obtained by calculating the square and evolution of the PWM signals in the cycle T of v(t). According to the alternating current signal effective value measuring device, the alternating signals v(t) for calculating the effective value are all alternating cycle signals, namely alternating current cycle signals containing direct current components and alternating current components, so that the alternating current signal effective value measuring device can effectively solve the problem that the signal to be tested contains direct current components and harmonic waves and is wider in application range.

The invention discloses an active damping optimization method for grid-connected current control of an L-type grid-connected inverter, which solves the problem that the control system is unstable dueto the existence of a digital control delay, and solves the problem of insufficient mid-band phase margin due to a compensation delay. The active damping optimization method includes the following steps: obtaining a difference delta ie of a beat delay output of a current reference preset value iL_ref and an actual current sampled value iL sampled by the system; adding a current prediction method,using the predicted inductor current as a research object, and compensating the delay link. The active damping optimization method is added to a current loop, which essentially adds a second-order differential feedback link into the current loop, the problem that the active high-frequency damping method is added to cause instable mid-frequency band of the system can be solved; a resonance peak caused by a system delay is suppressed; the stability of the system is improved; the gain range of current control is expanded; and dynamic and static errors of the system are reduced.

The invention discloses a direct hanging type large-capacity electric energy quality comprehensive managing device for an electrified railway. The direct hanging type large-capacity electric energy quality comprehensive managing device comprises an active compensation system and a passive compensation system. The passive compensation system comprises two passive high-pass filters for filtering higher harmonics out and providing partial capacitive reactive power, and the active compensation system is formed by connecting a plurality of active compensation units in parallel. The direct hanging type large-capacity electric energy quality comprehensive managing device has the advantages of being simple in structure, low in cost, good in reliability, capable of solving various electric energy quality problems and the like.

The embodiment of the invention provides an antenna connecting device, an antenna assembly and electronic equipment. The electronic equipment can be a mobile phone, a tablet personal computer, a notebook computer, a super mobile personal computer (UMPC), a handheld computer, an interphone, a netbook, a POS machine, a personal digital assistant (PDA), a wearable device, a virtual reality device, a wireless USB flash disk, a Bluetooth loudspeaker/earphone, a vehicle-mounted front part or other mobile or fixed terminals with antennas. Through the antenna connecting device, non-contact coupling connection between the antenna and the feeding point or the grounding point is realized, arrangement of an elastic bonding pad or a flexible metal buffer material on the antenna is avoided, arrangement of an elastic pin and a flexible metal buffer material on the feeding point or the grounding point is avoided, and the cost of antenna connection is reduced; and the occupied space of the antenna connecting device in the mobile phone is reduced.

According to a high-voltage direct-current urban rail transit traction power supply system, the input voltage of a main substation is converted into +/-10 kV or direct currents of other voltage classes and distributed to all traction substations, the output positive voltage of a direct traction station is connected to a traction network, and the output zero voltage of the direct traction station is connected to a walking rail. If a negative voltage output by the direct traction station is connected to the return line and the three-end voltage output by the direct current AT in the direct current autotransformer station is respectively connected to the traction network, the running rail and the return line, the direct current AT power supply system is formed. The multifunctional DC transformer in the direct traction station can realize bidirectional energy flow, so that high-voltage DC buses of stations such as a main substation, the direct traction station and a direct coupling stationand all DC capacitors on a traction network can be used as energy buffers during train braking, and the problem of train braking energy utilization is solved from the source. In addition, the systemcan effectively reduce rail potential and stray current.

The invention relates to a mobile outdoor high-voltage active filtering apparatus. The mobile outdoor high-voltage active filtering apparatus comprises a body; a main casing installed on the body; a power supply module installed on the body; and a high-voltage active power filter which is installed in the main casing and is connected with the power supply module. Compared to the prior art, the apparatus has the advantages of effectively solving the problem of system harmonic waves of a remote region, being good in safety and wide in application scope, and the like.

The invention relates to a converter switching frequency control method and system, and the method comprises the steps: firstly detecting actual harmonic content of a converter, then comparing the actual harmonic content with a set content threshold value, and controlling to improve the switching frequency of the converter when the actual harmonic content is greater than the set content thresholdvalue and the converter is in a seven-segment control mode; and when the actual harmonic content is less than or equal to the set content threshold and the switching frequency of the converter is greater than the minimum allowable switching frequency, controlling to reduce the switching frequency of the converter. When grid-connected stable operation of the converter can be ensured, according to the change condition of the harmonic content output by the grid-connected point, the working mode and the switching frequency of a switching device of the converter are correspondingly controlled and changed, it is guaranteed that the converter has small harmonic content within the full-power output range, low-harmonic and high-efficiency operation within the full-power interval of the converter isachieved, and the working efficiency of the converter is improved.