110results about "Reactive/real component measurements" patented technology

The present invention relates to a method of identifying the voltage stability of power grid in real time via figuring out the weak links of power grid; and uses a basic line voltage stability index BLSI or an extended line voltage stability index ELSI which is improved on the basis of the BLSI index to monitor, identify and judge power grid. The steps of identifying are as follows. Firstly, the requisite real-time date can be obtained via a PMU system or SCADA and EMS; Secondly, useless measurements get filtrated; thirdly, the parameters of the line are reassessed in real time if necessary in a given time interval; fourthly, a BLSI index or ELSI index is used to identify the weak links of the system; lastly, the system emergency protection control is started up to avoid the breakdown of system voltage at the BLSI value or ELSI value which is the weakest link that leads to voltage breakdown. The present invention has the advantages of identifying voltage invariability of the system in real time and weak lines and weak links that cause voltage breakdown of the system; and automatically dealing with actual loading properties relevant to voltage or frequency.

Aiming at a problem that an ip-iq algorithm cannot precisely acquire fundamental wave positive sequence active currents under the conditions of non-ideal power network voltages, the invention provides a method for detecting a harmonic wave and a reactive current based on spatial transformation of voltage vectors. The method comprises the steps of performing coordinate transformation on currents and voltages on an ip-iq algorithm channel to acquire phase information of three-phase fundamental wave positive sequence voltages; defining a p-q coordinate system; defining correct positive sequence active components and positive sequence reactive components by using the projection of a current vector on a voltage vector and a normal line thereof under the coordinate system; then accurately solving fundamental wave positive sequence active components, fundamental wave positive sequence reactive components, fundamental wave negative sequence active components and fundamental wave negative sequence reactive components in a load current by taking the correct positive sequence active components and the positive sequence reactive components as reference volumes and using an improved ip-iq algorithm; and popularizing the detection of the four fundamental wave current magnitudes into the detection of any sub-harmonic current magnitude to form a current detection system under the conditions of non-ideal voltages so as to provide reasonable reference instruction currents for various compensation requirements.

The invention provides a device capable of measuring physical quantity of alternating current at a long distance. The device comprises an analogue sampling passageway, a sampling switch, a register, a bus and a timing controller, wherein the analogue sampling passageway is used for inputting the alternating current to carry out analogue sampling so as to output an analogue sampling value, the sampling switch is used for resampling so as to obtain a remote-measurement data frequency required at a receiving side, the register is used for storing a resampling value from the sampling switch, the bus is used for outputting the resampling value in the register to the receiving side, and the timing controller is used for controlling resampling frequencies of the analogue sampling passageway and the sampling switch; and the device is characterized by further comprising a digital low-pass filter which is used for filtering a high-frequency component in the sampling value, wherein an input of the digital low-pass filter is connected with the analogue sampling value output by the analogue sampling passageway, an output of the digital low-pass filter is connected with the sampling switch, and cut-off frequency of the digital low-pass filter must be 0.5 folds smaller than the resampling frequency of the sampling switch. The invention also provides a corresponding method. When the device is adopted, the remote measurement accuracy of power physical quantity is increased, a waveform value is output through resampling, and an effective value, a steady-state value as well as a fundamental harmonic effective value and steady-state value are also output, so that many requirements of the receiving side for remote measurement data can be met.

System and methods in which endpoint control devices, such as, for example, switches and wall sockets, are arranged to monitor the power used by the controlled load as well as the power-factor of the load. In one embodiment, the monitored power and power-factor of a controlled device is fed back to a central point within the premises and then sent on to a more global monitoring point. In one embodiment, the endpoint device can send power parameter data to another location and receive instructions as to maximum allowable loads for a given power parameter or power-factor.

The invention relates to a method for detecting positive sequence, negative sequence, idle and harmonic currents of a power supply system. The detection method is based on three-phase voltage space vector oriented positive sequence synchronous coordinate rotation transformation, negative sequence synchronous coordinate rotation transformation and low-pass filtering. The method is very effective for detecting various positive sequence, negative sequence, idle and harmonic currents of three-phase four-wire and three-phase three-wire non-linear circuits. The method only transforms the tested current, and does not need to transform voltage. Therefore, the invention has the advantages of simple structure and clear conception. The invention is the simplest engineering method for dynamic and static idle and harmonic compensation.

Systems and methods thereof for obtaining metrics and an accurate threshold to prevent loudspeaker overheating, based on autocorrelation and cross-correlation of band-pass filtered current and voltage measurements are disclosed. The methods invented are based on instantaneous voltage and current measurements. The invention does not require a DC or pilot signal to be added to the audio signal in order to do perform the measurement, and it is not disturbed by capacitive or inductive components in the complex impedance of the voice coil.

The invention discloses an improved instantaneous symmetrical component method-based current detection method for a distribution static synchronous compensator (DSTATCOM), which comprises the following steps of: 1, determining a symmetrical component method and a method for expressing an instantaneous value in a phasor time domain; 2, determining the instantaneous value; 3, implementing the improved instantaneous symmetrical component method; 4, establishing a model by adopting a MATLAB simulation tool to perform simulation analysis on a conclusion; 5, filtering, converting and processing data; and 6, subtracting obtained three phases of positive fundamental active currents iafp<+>, ibfp<+> and icfp<+> from a load current to obtain required comprehensive compensation command currents iac, ibc and icc comprising harmonic components, negative sequence components and reactive components. The method avoids a complex phase shift circuit, a phase locked loop circuit, and an address generator and a table lookup process of sine and cosine function table, and eliminates errors and faults caused thereby.

The invention provides a static var compensation device current detection method based on transient power balance. The static var compensation device current detection method specifically comprises the following steps of: performing phase locking on the phase voltage of an A phase on the low voltage side of a transformer and the phase voltage of the A phase at a compensation point of a static var compensator (STATCOM); performing abc / pq transformation on the three-phase current n the low voltage side of the transformer according to a direction of a rotation vector of the phase voltage on the low voltage side of the transformer to obtain a reactive DC component of load current; converting the reactive DC component of the load current into a reactive current DC component required to be injected into the compensation point of the STATCOM as a q-axis DC component iqref of the output reference current of the STATCOM according to a transient power balance principle; and performing abc / pq inverse transformation on the iqref according to the direction of the rotation vector of the phase voltage at the compensation point of the STATCOM to obtain a three-phase output reactive current directive value of the STATCOM to control the actual output current of the STATCOM. By the method, the problems of current detection caused by the transformer crossing of the compensation point of the STATCOM and a load current detection point are solved, the STATCOM can be flexibly arranged at any position, and simultaneously, a reactive current detection algorithm is quick in response.

The invention relates to an intelligent monitoring system for the operation state of a low-voltage transformer area, and the system comprises a data collection module which is used for collecting operation parameter data; a topology identification data analysis module which is used for carrying out statistical analysis by utilizing a topology identification calculation model, identifying or verifying a box-table relationship and a user-transformer relationship to achieve topology identification mapping; and a topology identification imaging module which is used for visually displaying a data analysis result, dynamically generating a topological graph and performing real-time tracking verification, and supporting dynamic and conditional query of transformer area management, transformer areatopology, abnormity and analysis logs. According to the invention, a power grid safety power utilization management and safety operation and maintenance monitoring mode can be effectively realized, and a reliable basis is provided for overall planning and overall management of the power grid.

The invention discloses a compensating current detection method based on instant space voltage vector orientation .The compensating current detection method based on instant space voltage vector orientation comprises the steps that an on-voltage instant value and an on-current instant value are collected, coordinate transformation from three phases to two phases is carried out respectively, and two-phase instant voltage and two-phase instant current are obtained; a sinusoidal signal and a cosine signal corresponding to a phase angle of a three-phase composite rotational voltage vector are calculated through the two-phase instant voltage, the projection of the two-phase instant current value on the voltage vector is solved, and instant active current and instant reactive current are obtained; direct-current components of the instant active current and the instant reactive current are separated, a fundamental wave positive sequence current component is solved, coordinate transformation from two phases to three phases is carried out on the fundamental wave positive sequence current component, and a fundamental wave current component in three-phase current is obtained; three-phase compensating current is obtained by subtracting the fundamental wave current component from the three-phase current instant value .A compensating current instruction obtained with the method includes fundamental wave negative sequence current and harmonic current elements, and the ideal effects of suppressing harmonic waves and balancing three-phase loads can be achieved at the same time .

A power system measurement data time difference compensation state estimation method takes the quickest data acquisition time as the state estimation reference time to compensate measurement errors caused by other measurement time delays to obtain an updated electric network state. Regarding a PMU quick belt time mark measurement, updated real-time measurement data is adopted to take part in the state estimation and serve as the time of state estimation electric network section; regarding the measurements with time delays, corresponding time difference compensation factors are introduced according to the different time delays to finally obtain the updated state of the whole electric network through using the measurement variance of the updated continuous data section, modifying the time difference compensation factors according to the actual time delay conditions in the interactive process, and solving the time difference compensation state estimation equation.

The invention relates to an integrated processing system for real-time data of electric power based on cloud computing and a designing method. The computing and processing of tristate data can be completely realized by adopting a set of acquisition equipment and a set of distributed cloud storing, a cloud computing and cloud service mode, and respective computing values can be provided for various different application components so as to greatly reduce the number of configurated acquisition units of intelligent equipment; uniform data processing, computing and sharing are actually realized, a conventional functional device is changed into a functional component, the traffic and nodes on external network are effectively reduced, the communication network structure is optimized, and the network communication pressure is reduced, thereby being favorable for improving the system reliability and reducing the installation cost and maintenance expenses of the system.

An apparatus (1) for measuring the loss factor of an insulator (2) for medium or high voltages, equipped with a tap adapter (3) forming a point for picking up an electrical signal (4), comprises: a reference capacitor (9) having a first electrode (10), which can be connected to the tap adapter, and a second electrode (11); a first voltage detection module (12) operatively connected to the first electrode (10) of the reference capacitor (9) for detecting a signal representative of the voltage applied to the reference capacitor (9); an active electronic device (13) connected to earth and to the second electrode (11) of the reference capacitor (9) and configured to keep the potential of the second electrode (11) at a predetermined reference value; a second voltage detection module (14) operatively connected to an output of the active electronic device (13) in order to detect a signal representative of the electric current that flows through the reference capacitor (9).

The invention provides an APF (active power filter) harmonic wave detection system based on nerve network minimum root mean square and a detection method thereof. The system comprises an instruction current operation module, a current tracking control module, a driving module, and a main circuit module. The detection method comprises steps of calculating a demand signal, generating a PWM signal, amplifying the PWM signal and .generating compensation current. The system and the method have the following advantages: (1) hardware apparatus design is simple, cost is low, and realization is easy; (2) by employing a minimum root mean square harmonic wave current detection method, transient harmonic wave current in an electrical network can be detected accurately in real time, and compensation performance of an AFP is ensured; (3) through combining nerve network control with the minimum root mean square harmonic wave current detection method, a controller has self-learning capability; (4) the controller is not needed to be trained in advance, a dynamic response speed is fast, and a structure is simple.

Disclosed is a method for online detecting leakage resistive current of a lightning arrestor. The method includes that three components including a capacitive linear current component, a linear resistive current component and a non-linear resistive current component of leakage current of the lightning arrestor are subjected to superposition, namely IX=IC+IR+IF, before a reference point is found, the three leakage current components are separated into a linear part of IC+IR and a non-linear part of the IF, after a total leakage current waveform starting from a null point for a complete period is obtained, a maximum value is searched within the first 1 / 4 period to be the maximum value Im for the linear part, and position of the maximum value is tm; via computing, the non-linear resistive current component IF is obtained, the maximum value IF_Max is obtained to be the peak value of the non-linear resistive current component IF, and the peak value is taken as the reference point, the position of the peak value is tF, the value IX (tF-T / 4) at the position tF-T / 4 is found out on the total current waveform IX, and the value IX (tF-T / 4) is the peak value of the capacitive current component IC, and then an included angle alpha between the total current and resistive current and the peak value of the linear resistive current component IR is obtained via computing. The method for online detecting leakage resistive current of the lightning arrestor has the advantages of low cost, high precision, convenience in operation and the like.

The invention discloses a metallic oxide lightning arrester leakage current live test device and method. The test device comprises a noninductive shielding resistance and a lightning arrester leakage current tester, the noninductive shielding resistance is connected to a grounding wire of the metallic oxide lightning arrester in series, and disturbance of the surrounding electromagnetic environment for a leakage current can be shielded by the noninductive shielding resistance; a voltage transformer is connected with the two ends of the metallic oxide lightning arrester in parallel, the leakage current input end of the lightning arrester leakage current tester is electrically connected with the noninductive shielding resistance, and the input end of a reference voltage is electrically connected with a secondary voltage terminal of the voltage transformer. An analysis is carried out by the lightning arrester leakage current tester according to phase changes of the waveforms of a collected reference voltage signal and a leakage current signal, and the aging degree of the metallic oxide lightning arrester can be determined. According to the metallic oxide lightning arrester leakage current live test device and method, the metallic oxide lightning arrester leakage current can be simply, precisely and effectively tested, and the aging degree of the metallic oxide lightning arrester can be analyzed.

The invention relates to a measurement synchronization method and system for power electronic equipment. The method comprises a data transmission method, a period variable sampling method, and a zero-crossing synchronization method. The system is composed of an AD data sampling module, an AD data receiving and storage module, an AD data packaging module, an AD data sending module, a power grid voltage data analysis module, a zero-crossing time calculating module, a synchronous signal sending unit, a phase-locked loop module, a real-time power grid frequency calculation module and a sampling period adjustment module. According to the solution scheme provided by the invention, the structure of the system is simple and novel and the system is suitable for a digital signal processing chip. The method is simple; application is flexible; and the system and the method can be realized conveniently. A power grid frequency can be tracked in real time; and an actual voltage value, an actual current value, and an actual reactive value can be calculated accurately under the circumstance that the power grid frequency fluctuation is large. The method and system have wide application range and can be applied to an FACTS device and can be applied to all pieces of power electronic equipment needing realization of functions of period variable sampling and zero-crossing synchronization.

The invention discloses a double-voltage closed-loop-control harmonic current detection method and system. In an ip-iq detection method, a double-voltage closed-loop control is added so as to eliminate distortion generated during sudden change of load current; a novel low-pass filtering-based a-phase positive sequence voltage extracting unit is used for replacing a PLL phase-locked loop in the ip-iq detection method; under the condition of three-phase voltage distortion, the a-phase positive sequence voltage can be still normally extracted so as to accurately detect harmonic and reactive current. Simulating and studying results that by the double-voltage closed-loop-control harmonic current detection method, the distortion of the current during the sudden change of the load current can be eliminated, and under the condition of the voltage distortion, the harmonic component and the reactive current can be still correctively detected; under the condition that an instruction current has a very large sudden change, DC-side voltage closed-loop control and pressure-equalizing closed-loop control of upper and lower capacitors are added, so that zigzag distortion of grid current during the sudden change of the load current is avoided, and tracking and compensating characteristics are improved; the double-voltage closed-loop-control harmonic current detection method has wide applicability.

The invention discloses an active and passive component detection method for different current components in the distorted and asymmetric voltage state of electrical network. The method comprises the following steps that the angular frequency of voltage fundamental wave is extracted via a phase-locked loop, the voltage of the electrical network is switched into a dq coordinate system, and the initial phases of the negative sequence fundamental wave vector, the positive sequence kth harmonic wave vector and the negative sequence kth harmonic wave vector of the voltage are calculated respectively; the dq coordinate system is rotated so that the axis d is overlapped with the negative sequence fundamental wave vector, the positive sequence kth harmonic wave vector and the negative sequence kth harmonic wave vector of the voltage; current signals are transformed to the rotated dq coordinate system, and DC components are obtained by low pass filtering; and DC components of the axis d and the axis q in each dq coordinate system is transformed reversely to obtain corresponding active and passive components. When the voltage of the electrical network is distorted and asymmetric, the detection method can be used to accurately extract the active and passive components of the negative sequence fundamental wave vector, the positive sequence kth harmonic wave vector and the negative sequence kth harmonic wave vector of load current.

The invention discloses a lightning arrester resistive current and capacitive current transient value measuring method which includes that leaked current sampling values of a three-phase lightning arrester grounding down lead at all sampling times and high voltage side voltage sampling values of an A-phase lightning arrester at all sampling times are collected; phase angle of fundamental frequency voltage of high voltage side voltage of the A-phase lightning arrester, amplitude valueof fundamental frequency voltage, phase angle of tertiary voltage harmonic wave and amplitude value of tertiary voltage harmonic wave are calculated in a Fourier algorithm; influences of tertiary voltage harmonic wave and inter-phase coupling capacitance are considered, and transient values of capacitive current and resistive current in leaked current of the three-phase metallic oxide lightning arrester are obtained through calculation. According to the lightning arrester resistive current and capacitive current transient value measuring method, influences of tertiary voltage harmonic wave and inter-phase coupling capacitance are considered on a mathematical model, accurate measurement of the transient process of resistive current and capacitive current in leaked current of the three-phase lightning arrester is achieved, insulating property monitoring time points of the three-phase lightning arrester are shortened to all the sampling times, and reliable basis is provided for finding lightning arrester insulating property dynamic change conditions and fast making lightning arrester overhaul schemes.

The invention discloses a DSP (Digital Signal Processor) and SAPF (Shunt Active Power Filter)-based real-time phase shift detection system, which is characterized by comprising a signal reshaping and transformation processing circuit, a DSP central data processing circuit, an isolating and driving circuit and a thyristor circuit. A working method of the DSP and SAPF-based real-time phase shift detection system comprises coordinate transformation, filtration, calculation, phase shift and coordinate inverse transformation. The system and the working method thereof have the advantages that 1 three-phase voltage distortion, and fundamental wave positive sequence active current in case of asymmetry can be detected in real time by using a real-time phase shift method, 2 the speed and the accuracy of control are improved and the system has excellent adjustment performance and reliability, 3 the device capacity and the voltage level are greatly improved, the stability of a power grid is enhanced, and operation of the entire system is prevented from being influenced by harmonic pollution, and 4 the system and the working method thereof have broad market application prospect.

A method for determining a fault in a power filter of a wind turbine generator, the method including the steps of: calculating a reactive power consumed by the power filter; and comparing the calculated reactive power to a predefined threshold reactive power to determine the fault. A system for detecting a fault in a power filter of a wind turbine generator, and a computer readable medium containing computer program code for determining a fault in a power filter of a wind turbine generator are also disclosed.

The embodiment of the invention discloses a method and device for measuring parameters of the inner potential and the reactance of a synchronous generator and relates to the technical field of power system synchronous phasor measurement. The method comprises the steps that a generator end voltage phasor U( ), a generator end current phasor I( ), a generator power angle delta and a generator end voltage value U of the synchronous generator are measured and obtained through a synchronous phasor measuring device; a generator end power factor angle phi is generated according to the generator end voltage phasor U( )and the generator end current phasor I( ); the inner potential amplitude Eq of the synchronous generator is determined according to the generator power angle delta, the generator end voltage value U and the generator end power factor angle phi. The method and device can solve the problem that the inner potential amplitude is calculated through an indirect electric method currently, the result is not accurate, and large errors exist.

The invention relates to a quick harmonic and reactive current detection method based on the instantaneous reactive power theory. The method includes the step that a current disturbance system is provided. The current disturbance system comprises a control and monitoring unit. The harmonic and reactive current monitoring process of a current detection control circuit for monitoring harmonic and reactive currents in the system in the control and monitoring unit includes the steps that firstly, three-phase voltage and current instantaneous values in a three-phase power grid are collected; secondly, by the adoption of alpha-beta transformation, three-phase voltage and currents are changed into an alpha beta orthogonal stationary coordinate system; finally, virtual voltage vectors are added for replacing real voltage vectors participating in operation, instantaneous active and reactive power is calculated, and direct current power components are acquired through filtering of an LPF; fundamental components in detected currents are calculated through reverse transformation; harmonic components can be acquired by subtracting the fundamental components from the detected currents. The method can quickly detect harmonic currents and reactive currents.

The invention relates to a device for measuring resistive current fundamental component of a zinc oxide arrester; and the device comprises a data collecting unit LC1, a data collecting unit LC2 and a DSP (Digital Signal Processor) signal processor, wherein the data collecting unit LC1 is used for carrying out Fourier transform on a voltage signal Un and a voltage signal Us so as to obtain a fundamental phase Ph1 of the voltage signal Un relative to the voltage signal Us; the data collecting unit LC2 is used for converting a current signal Is into a voltage signal Us and carrying out Fourier transform on a power frequency leakage voltage signal Ux and the voltage signal Us so as to obtain a fundamental phase Ph2 of the power frequency leakage voltage signal Ux relative to the voltage signal Us; and the DSP signal processor is used for calculating a phase difference Ph of a power frequency leakage current signal Ix relative to the voltage signal Un according to the fundamental phase Ph1 and the fundamental phase Ph2. According to the invention, a complicated analog signal processing circuit is not needed, stability in long-time working is guaranteed and influences from harmonic interference can be effectively suppressed.

The invention discloses a method for acquiring excitation current characteristic quantities of a transformer online. The method comprises the steps of A, performing experimental acquisition of neutralpoint direct current and excitation current characteristic quantity sample data of the transformer; B, training a neural network; and C, acquiring the excitation current characteristic quantities ofthe transformer online. According to the invention, the direct current component of the neutral point current of the transformer can be measured online, four types of characteristic quantities, namely, the direct current component, the maximum value, the minimum value and the total harmonic distortion rate of the excitation current of the transformer can be calculated by fitting through utilizinga neural network algorithm, and a clear relationship between the excitation current characteristic quantities and the neutral point direct current of the transformer can be obtained, data support andguidance can be provided for analysis and suppression of direct current magnetic bias of the transformer, and the method has high engineering application value.

The invention discloses a three-phase voltage asymmetric ip-iq detection method. The three-phase voltage asymmetric ip-iq detection method is characterized by including: extracting A-phase positive sequence fundamental wave voltage, passing through a symmetric transformation unit T, extracting positive sequence signals ean of A-phase fundamental waves and subharmonic voltage, multiplying the ean and any sine or cosine signal matrix with initial-phase angle alpha to obtain es and ec, and filtering by a low-pass filter to obtain Es and Ec. The A-phase positive sequence fundamental wave voltage eal is obtained through matrix transformation on the basis, instruction signals ic* of compensating current are compared with actual compensating current signals ic, deviation delta ic of the instruction signals ic* and the actual compensating current signals ic serves as input of a hysteresis comparator, pulse width modulation (PWM) signals for controlling opening and closing of a main circuit are generated through the hysteresis comparator, and the (PWM) signals control closing and opening of a switch through a driving circuit so as to control variation of the compensating current ic. The three-phase voltage asymmetric ip-iq detection method is improved on the basis of an ip-iq detection method so as to be suitable for detection when three-phase voltage is asymmetric.

The present invention discloses a signal noise processing device during the electrical parameter metering process. The device comprises a waveform processing module, a metering operation module and a noise calculation module, wherein the above modules are electrically connected with one another. The waveform processing module is used for sampling an analog signal, converting the analog signal into a first digital signal and respectively outputting the first digital signal to the metering operation module and the noise calculation module. The noise calculation module is used for extracting a noise component from the first digital signal, adopting the noise component as a second digital signal and outputting the second digital signal to the metering operation module. The metering operation module is used for calculating the active power according to the first digital signal. The metering operation module is further used for calculating the average value of the active power and the second digital signal, so that the noise component in the average value of the active power is reduced. Based on the signal noise processing device, the extraction and the compensation for the key noise component of a small signal can be realized. The metering performance of the small signal is improved.

The invention discloses a fundamental wave positive sequence active current detection method and is applied to a voltage asymmetric or distortion three-phase system. The method comprises the following steps: step one, acquiring three-phase asymmetric voltage values for converting onto two mutually perpendicular coordinates through coordinate transformation; step two, after calculation of what is obtained from the first step, obtaining DC components through a low pass filter; step three, respectively multiplying the DC components obtained in the second step by the sine and cosine signal matrix of an initial phase angle pi / 4, and finally removing a negative sequence component including voltage fundamental waves through addition and subtraction operation; and step four, eliminating the sine and cosine signal matrix of the pi / 4 phase angle by use of the characteristic of a trigonometric function to obtain a voltage fundamental wave positive sequence component; and step five, after the voltage fundamental wave positive sequence component Uall is obtained, by use of a phase-locked loop and sine and cosine generation circuit, providing sine and cosine signals which have the same phase as an a-phase voltage fundamental wave positive sequence for a system, and finally obtaining fundamental wave positive sequence active current values. The detection method provided by the invention can accurately detect the fundamental wave positive sequence active currents in real time.