41 results about "Ac power system" patented technology

The invention discloses an alternating current power supply system low-voltage switch cabinet for an intelligent station and a power supply control method, and relates to the technical field of electric power automation and intelligent control, and the switch cabinet comprises an intelligent monitoring terminal, a transfer learning module, a self-adaptive optimization engine and an equipment fingerprint similarity evaluation module. According to the alternating-current power supply system low-voltage switch cabinet for the intelligent station and the power supply control method, a quantitative evaluation system is established through equipment composite fingerprint similarity evaluation, reliable improvement guarantee is provided for the reuse rate and the fault coverage rate after a fault prediction model is applied, and the reliability of the system is improved. Moreover, the isomorphic dual-channel feature fusion network improves the characterization capability of the time sequence dependence features and the topological correlation features, improves the intermittent fault detection rate, and achieves the exponential shortening of the model optimization period through the cooperation with incremental learning, thereby reducing the operation and maintenance cost, shortening the non-planned shutdown time of equipment, and improving the reliability of the system. And the autonomous operation and maintenance level of the smart power grid can be effectively improved.

The invention relates to an electric leakage suppression system for an alternating-current power system, and the system comprises a variable-frequency compensation control module which adjusts the frequency and signal amplitude in a circuit according to the equipotential characteristics of a power utilization loop of the power system, so as to match the load characteristics and achieve the dynamic fixation of the signal amplitude; the real-time monitoring module is used for monitoring the frequency, current and voltage of the power system; the central processing unit is used for processing data from the monitoring module, executing data analysis and identifying frequency and current changes under the condition of electric leakage or electric shock; and the electric leakage suppression module is connected with the real-time monitoring module, is provided with a mechanism which is automatically activated when frequency and current are detected to be abnormal, and is used for dynamically adjusting circuit response to suppress leakage current. And the modules are connected in parallel to the power utilization loop, perform rapid self-adaptive modified modulation compensation on the parallel frequency resonance of the load loop, and dynamically adjust the current phase and amplitude so as to realize the zero potential difference of the target load end and the current suppression on the target load, and form the suppression and shielding effects on the leakage of the circuit.

In a power conversion system, a first power converter is connected between a first AC power system, and a first DC main line and a DC return line. A second power converter is connected between the first AC power system, and the DC return line and a second DC main line. A first control device controls the first power converter in accordance with a first active power command value. A second control device controls the second power converter in accordance with a second active power command value. A common control device sets the first active power command value and the second active power command value by distributing a command value of total active power output from the entire power conversion system to the first AC power system. The common control device makes the first active power command value and the second active power command value different from each other.

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.

An electric power control system includes: a bidirectional electric power converter including AC and DC terminals, the AC terminal being connected to an AC power system, the DC terminal being connected to a DC power system to which one or more DC power loads are connected, the bidirectional electric power converter mutually converting AC power of the AC power system and DC power of the DC power system; an electric power storage that is connected to the DC power system and stores electric power of the DC power system; and a bidirectional electric power conversion controller that performs first control of controlling an output or input of the AC terminal of the bidirectional electric power converter such that a charge current, discharge current, charge electric power, or discharge electric power of the electric power storage coincides with a predetermined target current value or a predetermined target electric power value.

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.

1. Name of the Design Product: Prefabricated Cabin for Flexible AC Transmission Converter Valve. 2. Use of the Design Product: For dynamic power regulation, dynamic voltage control, oscillation suppression, and harmonic elimination in AC power systems. 3. Design Key Points of the Design Product: Lies in the shape. 4. Picture or Photograph that Best Illustrates the Design Key Points: Perspective view.

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.

To provide a power system switching device and a power system switching method for an AC power source which can switch power systems of the AC power source without stopping an AC motor by a simple device configuration even when power supply to the AC motor is blocked.SOLUTION: A power system switching device for an AC power source comprises: a first power system which supplies power from the AC power source to an AC motor; a second power system which is connected in parallel with the first power system to supply power in the same phase as power of the first power system from the AC power source to the AC motor; an uninterruptible power supply device which is connected between the AC power source and the AC motor in the second power system, stores power from the AC power source and supplies power to the AC motor; an overlap type power system switcher which switches a supply path of power to be supplied to the AC motor between the first power system and the uninterruptible power supply device; and a control unit which controls a switching operation of the overlap type power system switcher.SELECTED DRAWING: Figure 1

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.

The invention discloses a station AC power supply system protection setting value adaptation degree evaluation method and system, and the method comprises the steps: current amplitude adaptation: taking the protection of the current level as a reference, when the current protection action amplitude of the protection of the current level is smaller than that of the upper level, the adaptation of the current amplitude protection of the current level is 1, and otherwise, the adaptation is 0; action time adaptability: taking the protection of the level as a reference, when the action time of the protection of the level is smaller than that of the upper level, the adaptability of the action time of the protection of the level is 1, and otherwise, the adaptability of the action time of the protection of the level is 0; sensitivity adaptability: taking the protection at the level as a reference, when the sensitivity of the switch protection is not lower than a standard requirement, the adaptability of the sensitivity of the switch protection is 1, otherwise, the adaptability of the sensitivity of the switch protection is 0; according to the evaluation of the adaptation degree of the protection setting value of the alternating-current power supply system for the station, the weights of the three dimensions of current amplitude, action time and sensitivity are respectively taken for calculation, the adaptation degree of the protection setting value is estimated from the three dimensions of the current amplitude, the action time and the sensitivity of the protection setting value, and a reliability evaluation index is formed.

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).

This invention discloses a multi-source, partitioned, parallel underwater AC power supply network and method for substation noise reduction, relating to the field of ship AC power supply. The multi-source, partitioned, parallel underwater AC power supply network for substation noise reduction mainly includes multiple independent power supply zones and an integrated monitoring system. Each independent power supply zone supplies power to the loads in each power supply area of ​​the ship. Each independent power supply zone includes at least one AC power source and an AC distribution board. The at least one AC power source supplies power to the AC distribution board through an AC output switch. The AC distribution board supplies power to multiple loads in each power supply area through multiple AC switches. The AC distribution boards of the multiple independent power supply zones are electrically connected through interconnecting AC switches. The multiple independent power supply zones and the integrated monitoring system are electrically connected. Implementing the multi-source, partitioned, parallel underwater AC power supply network and method for substation noise reduction provided by this invention can improve the power supply reliability of the ship's AC power system.

The present invention discloses a method and circuit for monitoring insulation faults in a station AC power supply system, wherein the method comprises: collecting three-phase voltage, line current, and three-phase voltage phase angle; calculating the line current vector sum based on the line current, and calculating the line apparent power based on the three-phase voltage and the three-phase voltage phase angle; determining whether the line current vector sum is 0; if not, outputting a line-to-ground insulation fault alarm based on the line current vector sum; if so, determining whether the line apparent power is greater than a preset line apparent power; if so, outputting an inter-line insulation fault alarm based on the line apparent power. Since an insulation fault is detected in real time in the station AC system, an alarm is output, so that when the station AC system loses power or a protection malfunction occurs, maintenance personnel can perform maintenance on the station AC system based on the alarm to reduce the impact of the fault.

A portable residual current detection device belongs to the technical field of power grid monitoring. The invention aims to solve the problem that an existing residual current monitoring device of a low-voltage alternating-current power supply system cannot directly obtain a fault point. Current acquisition calipers are used for acquiring current signals of a neutral point of an alternating current power supply and a feeder line branch, a monitoring controller is used for independently calibrating current transmitted by each current acquisition caliper, and then current synthesis and dual-power-supply common-zero feeder line current synthesis are carried out on a feeder line zero line; the synthesized current received by the man-machine interaction unit is displayed, and a control port monitoring controller for recording the current of the zero feeder branch is provided for receiving a current recording control signal, recording the synthesized current and detecting whether the recording amplitude exceeds a threshold value or not, and if yes, an alarm signal is sent to the man-machine interaction unit; and the man-machine interaction unit is used for displaying the wave recording graph and the alarm signal. The method is mainly used for detecting the residual current of a station AC power supply system.

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

The present invention discloses a neutral point grounding method for a three-phase AC power system, which includes a neutral point. A switching device is connected between the neutral point and the ground. When the three-phase AC power system operates normally, the switching device is in an open state. When a single-phase grounding occurs in the three-phase AC power system, the switching device changes from the open state to the conducting state and then changes back to the open state after a preset period of time. And the electric energy accumulated on the switching device and the three-phase AC power system respectively by the current passing through the switching device within the preset period does not exceed the tolerance limits of the switching device and the three-phase AC power system. In this grounding method, when a single-phase grounding occurs, it can generate an obvious instantaneous large current, or directly trip the system to cut off the fault, or can successfully detect the single-phase grounding fault point.

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.

An AC electrical system for a vehicle and a method of operation thereof are provided. In one aspect, an AC electrical system includes a first electric machine mechanically coupled with a first spool of a gas turbine engine and a second electric machine mechanically coupled with a second spool of the gas turbine engine. The system also includes a first AC bus and a second AC bus. A first electrical channel electrically couples the first motor to the first AC bus and a second electrical channel electrically couples the second motor to the second AC bus. The system also includes one or more connection links and one or more power converters for selectively electrically coupling the first electrical channel and the second electrical channel such that power generated by one electric machine can be converted and shared with electrical loads of the other electric machine and the other channel.

The invention discloses a temperature control load frequency modulation method and system considering a node frequency differentiation dead zone, and the method comprises the steps: building a relation between each node frequency in a synchronous AC power system and the rotating speed of a synchronous power supply, and obtaining the time domain expression of the node frequency; setting the maximum load fluctuation at the node where the temperature control load is located, and taking the node frequency deviation at the moment as a frequency modulation action dead zone of the temperature control load of the node; determining the adjustable power and the adjustable time of the temperature control load, and setting a temperature control load droop coefficient based on the adjustable power and the adjustable time, so that the temperature control load fully utilizes the adjustable power under the expected maximum disturbance; and adjusting the power of the temperature control load by using the set droop coefficient in response to the fact that the frequency of the node where the temperature control load is located exceeds the frequency modulation action dead zone. After the differential dynamic dead zone is provided, the temperature control load does not malfunction under normal load fluctuation, the self adjustable capacity can be fully utilized after disturbance occurs, and a better frequency modulation effect is achieved.

The utility model relates to the technical field of residual current on-line monitoring, in particular to a residual current on-line monitoring and protecting device for an alternating current power supply system for a transformer substation, which comprises a residual current transformer unit, a 485 communication acquisition unit, a wireless LORA acquisition unit, a magnetism gathering iron core unit, a data gathering unit and a comprehensive monitoring management terminal, the magnetism gathering iron core unit and the residual current transformer unit are both arranged on an external cable to be monitored, the residual current transformer unit is electrically connected with the 485 communication acquisition unit and the wireless LORA acquisition unit, the wireless LORA acquisition unit is electrically connected with the comprehensive monitoring management terminal through the data collection unit, the magnetism gathering iron core unit is electrically connected with the wireless LORA acquisition unit, and the wireless LORA acquisition unit is electrically connected with the comprehensive monitoring management terminal through the data collection unit. The 485 communication acquisition unit is electrically connected with the comprehensive monitoring management terminal, and can measure the residual current of a plurality of lines at the same time and wirelessly transmit the residual current to the terminal for monitoring.