20 results about "Ac power system" patented technology

A power control system includes: a first energy storage system; a bidirectional AC / DC converter connected between an AC power system and the first energy storage system; and a control device for controlling an operation of the bidirectional AC / DC converter. The control device controls the operation of the bidirectional AC / DC converter to control charging and discharging of the first energy storage system. The power control system includes: a circuit breaker connected between the AC power system and the bidirectional AC / DC converter; a resistor connected between the circuit breaker and the bidirectional AC / DC converter; and a switch for forming a discharge path for discharging the DC power of the first energy storage system via the resistor, while the circuit breaker is open.

The invention discloses a self-healing parallel capacitor aging test device and method for an AC power system. The method comprises the following steps: S1, preparation before test; s2, carrying out a first-stage aging test; s3, carrying out a charge-discharge cycle test; s4, performing a second-stage aging test; and S5, detecting after the test. According to the self-healing parallel capacitor aging test device and method for the alternating-current power system, automatic control over the whole test process is achieved, it is guaranteed that test conditions meet the national standard requirement, the influence and closing impact on a power grid in the test process are eliminated, the accuracy and reliability of a test result are improved, and the test efficiency is improved. A standardized method is provided for performance evaluation of the capacitor, and the problems that an existing test device is low in integration and automation degree, poor in test precision, large in power grid influence and insufficient in safety protection are solved.

A system for frequency regulation in a AC power supply system is disclosed, wherein the system comprises an uninterruptible power supply being electrically connected to the AC power supply system and comprising a phase-locked loop and / or a frequency-locked loop for monitoring the frequency of an AC input voltage received from the AC power supply system, wherein the phase-locked loop and / or the frequency-locked loop is / are designed to be operated with an operation frequency being higher than a nominal grid frequency and being selected to detect a deviation of the monitored frequency from the nominal grid frequency within a predefined time span after a frequency drop-off of the monitored frequency occurred, wherein a control signal (19) is generated based on the detected deviation of the monitored frequency from the nominal grid frequency, and wherein the generated control signal is used to regulate the power flow between the uninterruptible power supply.

The invention belongs to the field of airborne power system design, and particularly relates to a stability constraint method for an MEA variable-frequency alternating-current power system. The method comprises the following steps: firstly, establishing a port impedance / admittance model of each device in a system; secondly, analyzing the stability of each subsystem, and redesigning if the stability margin does not meet the requirement; then, on the premise that all subsystems are stable, the overall stability of the system is analyzed according to a generalized Nyquist stability criterion; if the whole system is unstable or underdamped, quantitatively identifying a high-influence negative subsystem with the maximum stability deterioration degree in a mode of setting admittance of a load-side subsystem to be zero; and finally, the stability margin of the high-influence negative subsystem is improved by redesigning the high-influence negative subsystem. The MEA variable-frequency alternating-current power system is ensured to have enough stability margin in the design stage, so that the stability problem is avoided.

A three-phase UPS system (1) comprises a rectifier (100) and a battery (200). The rectifier (100) has an input side (101) being connectable to an AC power system (2) to provide first input power and to the battery (200) to provide second input power to the rectifier (100). The rectifier (100) has an output side (102) to provide a DC output power in response to a power share of the first input power and the second input power. The rectifier (100) is configured to be controlled such that the power share is adjustable.

A power conversion device (1) comprises: a power converter (4) that is connected to a three-phase AC power system (2) and has a self-extinguishing type semiconductor switching element (Q); and a converter control unit (7) that controls the power converter (4). The converter control unit (7) includes a reverse-phase reduction control unit (8). When an unbalanced fault in which the amplitude of the voltage of at least one phase decreases occurs in the AC power system (2), the reverse-phase reduction control unit (8) generates a reverse-phase current command value for adjusting the phase of the reverse-phase voltage of the AC power system (2) to reduce the maximum value of the amplitude of the voltage of a sound phase in which the unbalanced fault has not occurred. The converter control unit (7) controls the on / off of the semiconductor switching element (Q) on the basis of the reverse-phase current command value.

The embodiment of the invention discloses a control method and a control device of a power supply system and the power supply system. The control method comprises the following steps: monitoring an output waveform of a comparator unit; whether the time interval between the rising edge and the falling edge of the output waveform of the comparator unit meets a preset time threshold value or not is judged, the preset time threshold value is determined based on preset threshold voltage and the output waveform of the main power supply, and the preset threshold voltage comprises first threshold voltage and second threshold voltage; the first threshold voltage is higher than the second threshold voltage; if yes, the power supply system does not need to switch the standby power supply and continues to use the main power supply to work; and if not, determining that the main power supply has an overvoltage or undervoltage fault, and controlling the power supply system to be switched from the main power supply to the standby power supply for working. According to the embodiment of the invention, the technical problems of low main and standby power supply switching detection precision, slow response speed and poor anti-interference capability of the AC power supply system in the prior art are solved.

A power conversion system including: a self-excited power converter that converts power between an alternating-current (AC) power system and a direct-current (DC) line; an AC circuit breaker disposed between the AC power system and the self-excited power converter; an arrester connected between the DC line and a ground or between an AC line and the ground, the AC line connecting the AC circuit breaker and the self-excited power converter; and a control device. The control device causes the self-excited power converter to stop a switching operation when the control device detects a ground fault accident on the DC line, and opens the AC circuit breaker after the self-excited power converter stops the switching operation.

A power conversion system including: a first self-commutated converter connected between a first AC power system, and a first DC main line and a DC return line for first high voltage DC transmission; a second self-commutated converter connected between the first AC power system, and the DC return line and a second DC main line for second high voltage DC transmission; and a control device, wherein when detecting a single or double line to ground fault inside the second self-commutated converter and detecting an occurrence of a missed zero crossing in a non-faulted phase of the first AC power system, the control device causes the first self-commutated converter to output a DC component for eliminating the missed zero crossing to the first AC power system, and then opens an AC circuit breaker in order to separate the second self-commutated converter from the first AC power system.

This invention relates to the field of electrical parameter measurement and analysis technology, and particularly to a method, system, and medium for measuring the initial phase of amplitude-frequency oscillations in AC power systems. The method includes: acquiring three-phase voltage sampling signals; constructing a mathematical model of the oscillation signal based on the sampling signals; performing coordinate transformation on the sampling signals to obtain direct-axis and quadrature-axis components; constructing an amplitude oscillation signal based on the direct-axis and quadrature-axis components and separating the amplitude modulation component; performing analytical expansion of the frequency modulation term based on the mathematical model of the oscillation signal to obtain an analytical expression for the frequency oscillation; performing frequency domain transformation on the time-domain signals corresponding to the amplitude oscillation signal and the analytical expression for the frequency oscillation, respectively; determining the initial phase of the amplitude modulation based on the phase information of the disturbance frequency component; and calculating the initial phase of the frequency modulation based on the phase relationship between the subsynchronous or supersynchronous component and the power frequency component. This invention effectively solves the problem of accurately measuring the initial phase of oscillations when amplitude-frequency oscillations occur at the grid connection point.

The invention belongs to the technical field of aircraft variable-frequency alternating-current power supply system design, and particularly relates to an anti-interference method and device for eliminating sudden loading and network quitting of a variable-frequency alternating-current power supply system. The method comprises the following steps: periodically collecting frequency signals output by a generator, and storing the frequency signals in a queue with a preset length of N; performing filtering processing on the frequency signals in the queue to obtain a frequency average value for judgment; if the frequency average value is lower than the network exiting frequency threshold value, the overclocking identification position is 1, and the period count values are accumulated; if the frequency average value is not lower than the network exiting frequency threshold value, resetting the overclocking identification bit and the period count value; and when the overclocking identification bit is 1 and the period count value reaches a threshold value, controlling the main contactor of the generator to be switched off, so that the power supply system exits from the power grid, otherwise, carrying out detection of the next period. According to the method and the device, the abnormal network quit phenomenon in the system loading process is avoided, and the reliability of the power supply system is improved.

An instantaneous voltage command value calculation unit (140) uses a reference operation phase (θop) and a voltage amplitude command value (Ve) to generate instantaneous voltage command values (Vu*, Vv*, Vw*) of an output voltage to an AC power system in which current suppression control is reflected, wherein said reference operation phase (θop) and said voltage amplitude command value (Ve) are calculated by control calculation based on AC detection values (Vsys, Isys) classified as an active component and a reactive component by a coordinate conversion performed by a coordinate conversion unit (105). A PWM calculation unit (150) generates on / off command signals (Sgu, Sgv, Sgw) for switching elements constituting the power conversion device, in accordance with the instantaneous voltage command values (Vu*, Vv*, Vw*). A rotation phase (θdt) used for the coordinate conversion in the coordinate conversion unit (105) is set so that the phase of the instantaneous voltage command values (Vu*, Vv*, Vw*) matches the rotation phase (θdt).

To protect an AC power system more completely than before.SOLUTION: A protection system (110) for protecting an AC power system (100) includes a compensation reactor (5), a capacitor (6) connected in series with the compensation reactor (5), and a bypass circuit (BP) connected in parallel with at least one of the compensation reactor (5) and the capacitor (6).SELECTED DRAWING: Figure 2

This application provides a generator controller control method for a constant frequency AC power system to solve the engagement problem caused by the weak constant load capacity of the constant frequency AC power system at low speeds. The method includes: periodically acquiring the generator excitation voltage, frequency, generator control switch signal, main contactor signal, and generator three-phase current obtained through the current transformer; when it is determined that the generator excitation voltage and frequency are less than predetermined values, and the generator control switch signal and main contactor signal are both on, and any current in the three-phase current transformer is less than a predetermined value, a chopping indicator is generated; based on the chopping indicator, the voltage regulator is controlled to disable operation, so that the excitation current in the generator excitation circuit undergoes a chopping process to adjust the duty cycle of the excitation current, thereby reducing the generator three-phase AC output voltage, reducing the load power, increasing the generator frequency, and causing the constant frequency AC power system to enter underfrequency protection, thus solving the main contactor engagement problem.

Techniques for alternating current (AC) powering methods deployed at a power transmitter and a power receiver for line fault detection. AC power is applied to a pair of lines at a power transmitter to transmit the AC power to a power receiver. An occurrence of a predetermined characteristic of an AC voltage waveform or an AC current waveform is detected. The AC power is disconnected from the pair of lines upon detecting occurrence of the predetermined characteristic. Fault detection is performed during a safety check time window upon disconnecting the AC power from the pair of lines. The AC power is reconnected to the pair of lines when a fault is not detected from the fault detection during the safety check time window, and the AC power is maintained disconnected from the pair of lines when a fault is detected during the safety check time window.

The power conversion system of this embodiment includes multiple converters and a control unit. The multiple converters are arranged in parallel phase-to-phase configuration for each phase of a multiphase AC power system. The control unit uses multiple carrier signals with a predetermined phase difference to perform PWM control on the multiple converters. At predetermined time intervals, a predetermined number of even-numbered timings are determined within one cycle of a specific carrier signal. At each of these even-numbered timings, the control unit detects the primary-side current of the multiple converters. The control unit uses the detected primary-side current value and a primary-side current reference value to generate a voltage reference for the PWM control, and updates the voltage reference at each of the four or more even-numbered timings. The control unit uses the specific carrier signal and the updated voltage reference to control a specific converter among the multiple converters.

The invention discloses a multi-mode intelligent alternating current electricity testing and operation process safety monitoring method and device only suitable for an alternating current power system, and belongs to the technical field of power system safety operation and maintenance. According to the method, a multi-mode electricity testing mechanism combining power frequency non-contact type electric field perception and contact type electricity testing is adopted, the intensity of an electric field is detected in real time through a handheld device, image acquisition is automatically triggered, a deep learning model is used for carrying out target recognition and electricity testing position correctness verification on power equipment, and it is ensured that the electricity testing position is accurate. After the electricity testing data is packaged, encrypted and uploaded, the device realizes hardware locking of no-electricity-testing forbidden grounding wire hanging according to the data, and continuously monitors the electric field change during the period from electricity testing to grounding completion, thereby preventing the risk of sudden power transmission. The device is composed of a handheld electricity testing device, a monitoring terminal and a cloud platform, a complete and safe closed loop of sensing, recognition, verification, locking and monitoring is formed, the technical problems that a traditional electricity testing technology is low in safety and prone to misjudgment, and the process is not traceable are effectively solved, and the intrinsic safety level of electric power operation is remarkably improved.

In a control device of a power conversion device, in order to control an AC current outputted from a power converter, a first generator generates a first voltage command value based on a positive-phase current command value and a given reverse-phase current command value. A reverse-phase voltage compensator generates the reverse-phase current command value to compensate for a reverse-phase component contained in an AC voltage of an AC power system. When a state in which imbalance is determined as being minor based on comparison of an assessment value relating to a degree of imbalance of the AC voltage of the AC power system with a threshold value continues for a certain time period or longer, the reverse-phase voltage compensator generates the reverse-phase current command value and provides the reverse-phase current command value to the first generator.

An active filter circuit is connected to a power reception end of a power line that supplies AC power supplied from an AC power system or a DC power source interconnected with the AC power system or DC power supplied from the DC power source to a power conversion device, reduces a harmonic component of conducted noise propagated to the power line, and outputs to the power line, and a control section monitors a state change of input power input to a power module that generates driving power of an active element constituting the active filter circuit or a state change of the driving power supplied from the power module, and diagnoses an abnormality of circuit operation of a circuit including the active element of the active filter circuit based on the state change of the input power or the state change of the driving power.

The invention relates to the technical field of cable damage detection, and discloses a 400V plant AC power supply system cable and load insulation fault on-line detection device, which comprises a pulse instrument, the socket position of the pulse instrument is in buckle connection with a contraction conduction wire, and one end, far away from the pulse instrument, of the contraction conduction wire is fixedly connected with a metal pipe. In order to solve the problem that the connecting position of a metal pipe and a metal clamp is abraded, when a worker presses the metal clamp every time, the metal clamp drives a sliding frame to slide along the outer wall of a track through a rotating rod, a rotating plate forces a rotating ring to rotate along the outer wall of the metal pipe along with downward sliding of the sliding frame, and the metal pipe drives a bidirectional threaded pipe to rotate; the two-way threaded pipe forces the meshing ring to perform intermittent reciprocating sliding, the meshing ring drives the rubber ring to perform short-distance sliding along the outer wall of the contraction conduction wire through the fixing rod, the contact position of the rubber ring and the contraction conduction wire is changed, and the problem that the skin of the contraction conduction wire is damaged due to the fact that a single position bears torsion pressure for a long time is prevented.