66 results about "Neutral systems" patented technology

The invention relates to a fault identification method for an isolated neutral system. According to the method, zero sequence voltage abrupt change amount detection is additional arranged in the initial phase of the algorithm and single-phase earth fault line selection is judged; then in order to reduce harmonic interference and accurately judge initial time of the fault, a negative sequence amount threshold value is set so that negative sequence amount of unbalance in normal operation is avoided; and non-earth fault line selection is judged according to the characteristics that zero sequence and negative sequence components do not exist in the system and high fault abrupt change current exists in the fault line when three-phase short circuit occurs. Group amplitude and phase comparison and zero sequence reactive power direction line selection methods are integrated in the aspect of algorithm, and variable threshold detection is additionally arranged so that interference of harmonic waves on the line selection process can be effectively reduced, and the complete fault identification method for the isolated neutral system is formed.

A load center with a circuit breaker with a first recess and a second recess, a main busbar with a first stab that is operatively arranged to insert into the first recess and support a front end of the circuit breaker. The load center also includes a neutral support bar having a second stab and a lug. The lug is connected to a neutral system and the second stab is operatively arranged to insert into the second recess of the circuit breaker. The second stab also supports a back end of the circuit breaker.

The invention relates to a fault phase selection method for an isolated neutral system, which comprises the following steps: step one, grounding fault judgment, wherein the step further comprises the sub-steps of (1) grounding fault judgment, (2) single-phase grounding fault judgment and (3) two-phase grounding fault judgment; and step two, non-grounding fault judgment, wherein the step further comprises the sub-steps of (1) asymmetric fault judgment, (2) two-phase short circuit judgment and (3) three-phase short circuit judgment. According to the invention, algorithm improvement is performed on a current difference sudden change phase selection method, the current difference sudden change phase selection method is divided into a grounding short circuit fault phase selection method and a non-grounding fault phase selection method according to characteristics of a line after a fault occurs, and a set of complete fault phase selection method for the isolated neutral system is formed. The method has very high phase selection reliability for isolated neutral systems which are complicated in harmonic wave, strong in electromagnetic interference, instable in operating mode and high in grounding resistance, and can act as a common means for fault phase selection for the isolated neutral system.

The invention discloses a single-phase grounding simulation modeling system of a power distribution network. The single-phase grounding simulation modeling system of a power distribution network is only suitable for carrying out qualitative analysis of the transient characteristics and steady characteristics when a singlephase earth fault occurs in an isolated neutral system and a neutral point grounding system through an arc extinguishing coil. The single-phase grounding simulation modeling system of a power distribution network applies incorporation and simplification on complicated network branches, and can carry out qualitative simulation analysis for a mainstream fault line selection method. Aiming at the factors influencing singlephase earth fault line selection of the power distribution network, such as a line type, a fault position, a grounding resistor and an initial phase angle, the single-phase grounding simulation modeling system of a power distribution network can simulate the current changing characteristics of the grounding fault, the current changing characteristics of different injection signal modes, the current changing characteristics of different injection resistance/reactance and the related electrical quantity characteristics so as to obtain single-phase grounding and the general changing rules of the fault characteristics when the neutral point is ungrounded and the neutral point is grounded through the arc extinguishing coil, and can also perform power distribution network single-phase grounding line selection and positioning method verification. The single-phase grounding simulation model of the power distribution network has high applicability and a wide simulation range.

The invention discloses a method for testing a capacitive current of an isolated neutral system, and belongs to the technical field of high-voltage testing. The method includes the steps that different-frequency signals are injected from the neutral point of a capacitor bank (2) by a single-phase electromagnetic voltage transformer (6) through an insulated cable (5), and the capacitive current of the isolated neutral system is obtained through calculation. The method can be carried out in an electrification mode, the problem that an original capacitive current test is low in testing efficiency, inaccurate in testing result, unsafe in testing method and the like is solved, and the testing method provides a basis for accurately measuring the capacitive current of the isolated neutral system and allocating an arc suppression coil according to the testing result or checking the capacity of the arc suppression coil.

The invention discloses a control method for developing time delay and derivative dependency thereof through a linear memoryless state feedback control law for uncertain neutral systems with time-varying delay, incentive restraint and norm-bounded parameters to ensure local stabilization of a closed ring system in a predetermined attraction domain in an initial state, provides an LMI optimization method to design state feedback gain to make an estimation value in the attraction domain maximum, solves an attraction domain estimation value with less conservative property based on a Lyapunov-Krasovskii function method, and provides solution conditions and solution strategies for the deigns in an LMI form.

The invention relates to a comprehensive automatic monitoring method for a middle-voltage power supply system, which solves the problem that a faulty line is selected correctly in a short time when an isolated neutral system or a small current grounding system has single-phase grounding failure and puts forward an opinion that during line selection process, a comparison is made between the time value of reference quantity and the time value of zero-sequence current at the same time and a method comprising the steps of sampling and wave-recording for 24 hours, continuously recording the condition of each electrical quantity, carrying out data analyzing and processing, releasing warning, displaying and storing results once abnormal conditions occur and unloading the results by a remote transmitting system. The method has simple calculation and high correctness. As a device collects all electrical quantities of a power substation, the statistics of situation that a main transformer is impacted by short cut, analysis on the harmonic components of current and the statistical calculation of the qualification rate of voltage can be achieved.

The invention discloses a grounding fault detecting method based on a steady state fault quantity. The method comprises the following steps: collecting a three-phase voltage, a zero-sequence voltage and a zero-sequence current of a system to be detected; comparing whether the zero-sequence voltage is greater than a starting threshold value of the zero-sequence voltage, if so, judging that a single-phase grounding fault occurs in the system; if the single-phase grounding fault occurs, comparing a size of the three-phase voltage, judging that a lagging phase of a maximum voltage phase is a faultphase, and calculating an amplitude value and a phase of a fault phase voltage at this moment and an amplitude value and a phase of the zero-sequence current; comparing sizes of the fault phase voltage and a high-resistance grounding voltage threshold value, if the fault phase voltage is greater than the high-resistance grounding voltage threshold value, judging that a high-resistance grounding fault occurs, and according to a phase relation of the fault phase voltage and the zero-sequence current, judging whether a single-phase high-resistance grounding fault occurs in the circuit. The method is weak in dependence to a fault starting moment, and capable of completing single-phase high-resistance grounding fault detection of an isolated neutral system.

The invention discloses a preparation method of enzyme-hydrolyzed butter with a high flavor intensity and use thereof in essence with a milk flavor. In the method, a neutral system prepared by mixing butter and water is used as a screening module, and one or a mixture of several of a group of screened lipases is subjected to enzymolysis reaction to form a group of corresponding enzyme-hydrolyzed butter products; the group of products are treated by an acid value and gas value combined analysis method under the same process conditions to determine the flavor materials of the enzyme-hydrolyzed butter; and the final preparation method is determined when final products of the same acid value and flavor components under the same process. In the invention, the flavor intensity of the enzyme-hydrolyzed butter is improved by screening and evaluating lipase and controlling an enzymolysis process. The final products can be used as raw materials for preparing the milk-flavor essence with improved mellow taste and long-lasting fragrance and can be applied to baked products.

An extracting method of a reference voltage of a dynamic voltage restorer in an isolated neutral system comprises the steps that amplitudes of phase voltages of an A phase, a B phase and a C phase and amplitudes of three line voltages on the DVR system side are measured after faults, the minimum value and the maximum value of the amplitudes of the three line voltages are respectively obtained to judge whether falling off can be compensated, if falling off can be compensated, the measured amplitudes of the three phase voltages on the DVR system side can be compared with corresponding rated values, the procedure is completed when it is determined that no fault occurs according to comparing results, and voltages on the DVR load side after compensation are obtained according to fault types when it is judged that the faults occur; it is determined that reference voltages of the phases of a DVR are phasor differences of the voltages on the DVR system side after compensation and the voltage on the DVR system side after the faults. The voltages needing to be compensated by the DVR can be obtained only by detecting the amplitudes of the phase voltages and the amplitudes of the line voltages on the DVR system side, implementation is easy to achieve, and important practical value is brought to improvement on the practical level of the DVR in the isolated neutral system.

The invention discloses a ferromagnetic resonance fault detection method for an isolated neutral system. Three-phase voltage and a zero-sequence voltage signal of a bus are analyzed to detect the ferromagnetic resonance fault of the system. According to the method, with Hilbert Huang transform (HHT) based on empirical mode decomposition (EMD) as the core, in combination with FFT, FFT analysis is firstly performed on the three-phase voltage and the zero-sequence voltage signal, then HHT analysis is performed, and finally the moment of ferromagnetic resonance and the amplitude value of ferromagnetic resonance over-voltage are obtained through a three-dimensional Hilbert spectrum, so that the ferromagnetic resonance type, the amplitude value and the inducing moment are accurately analyzed in a quantified mode. The HHT signal analysis method is adopted for completely getting rid of linearity and stability constraints, namely, frequency-domain analysis can be performed on the voltage signal, and meanwhile time-domain analysis can be performed; in the process of HHT analysis, an RBF-point symmetry continuation method is adopted, in combination with a mirror image continuation method, the end effect of HHT is improved, and mode superposition is avoided.

The invention discloses a method for acquiring a single-phase earth fault current of a three-phase three-core cable. The head end of a three-phase three-core cable shielding layer is serially connected with a zero-sequence current transformer, the three-phase three-core cable shielding layer is earthed through the zero-sequence current transformer and is used for acquiring the capacitance current without being influenced by a load imbalance current when the single-phase earth fault of the three-phase three-core cable is caused, so that the insulation property of the three-phase three-core cable can be well reflected; a voltage limiter is arranged on the far end of the three-phase three-core cable shielding layer, when the voltage of the three-phase three-core cable shielding layer raises to a limit value, the voltage limiter is of low impedance to guide current to the earth, the zero-sequence current transformer is not limited by the impedance, the number of turns of a primary side can be increased freely, so that the sensitivity of the protection of a low-current grounding and isolated neutral system is improved; and meanwhile, an iron core of the zero-sequence current transformer can adopt a cold-rolled particle oriented silicon steel sheet with high magnetic conduction property, so that high-frequency transient current when the earth fault is caused can be well reflected, the protection sensitivity is improved, and the strong popularization and application value is achieved.

The invention discloses a preparation method of monodispersed conductive polymer microspheres with core-shell structure, which relates to a conductive polymer microsphere and provides a preparation method of monodispersed conductive polymer microspheres with core-shell structure. The stabilizing agent and lower alcohol mediator are added to a reactor, stirred and warmed up to dissolve the polyvinyl pyrrolidone; the vinyl monomers dissolved with initiators are added to obtain the polymer dispersion liquid which is then centrifugal separated; the stabilizing agent and lower alcohol adsorbed on the polymer microsphere surfaces are washed out; the polymer microspheres are positioned inside the reactor after being dried, then water is added enabling the polymer microspheres occupying 10% to 30% of the whole reacting system; oxidant is added after ultrasonic decentralization; inorganic acid is added after the oxidant is dissolved; conductive polymer monomers are injected after ice-water bath; and then ice-water bath, coating polymerization while stirring, centrifugal separation of the production, repeating washing by deionized water for the neutral system, and vacuum desiccation are performed.

This invention relates to one functional central neutral damage dialogue test protein chip and its process method, which comprises the following steps: using protein chip to fix multiple central neutral system damage generation development key function abnormal protein factor antigen and its array; the said protein antigen and its array abnormal protein factors act as key property protein factors in the neutral system for inflammation and activation reaction and cell ion balance adjust and signal transmission.

The invention provides a single phase earthed relay protection device, comprising a signal acquisition module, a signal processing module, a fault judging module, a releasing module and a power supply module, wherein the signal acquisition module is used for acquiring current transient state traveling waves and voltage transient state traveling waves of a line; the signal processing module is used for respectively acquiring a wave head polarity of a current transient state traveling wave modulus and a wave head polarity of a voltage transient state traveling wave modulus from the current transient state traveling waves and the voltage transient state traveling waves; the fault judging module is used for comparing the wave head polarity of the current transient state traveling wave modulus with the wave head polarity of the voltage transient state traveling wave modulus, which are acquired by the signal processing module, and determining that a single phase earthed fault is generated when the two wave head polarities are opposite; the releasing module is used for release the output of the fault judging module; and the power supply module is used for supplying power for the single phase earthed relay protection device. Through the technical scheme in the invention, the defects that the traditional protection method of the non-effectively earthed neutral system is insensitive or disabled due to unobvious single phase earthed fault phenomena is overcome, and the sensitivity and the reliability of single phase earthed relay protection are improved.

The invention provides a singlephase earth fault signal generating device and method for a simulation isolated neutral system. The singlephase earth fault signal generating device for a simulation isolated neutral system comprises a three-phase 10KV power line, a single-stage breaker, a disconnecting switch and a grounding resistor group, wherein one end of the single-stage breaker is connected with a one-phase power line among the three-phase 10KV power line; the other end of the single-stage breaker is connected with one end of the grounding resistor group through the disconnecting switch; and the other end of the grounding resistor group is grounded. The singlephase earth fault signal generating device for a simulation isolated neutral system determines the grounding type of the simulation isolated neutral system by means of simulation grounding under different analog quantity and adjusting of the grounding resistor group and according to the angular phase difference variance, caused by different grounding resistance values, of the zero sequence voltage, the zero sequence current, the opening triangle voltage and the zero sequence current voltage of a sampling zero sequence voltage transformer group, so as to provide power transmission and distribution early warning parameters for a high resistance singlephase earth fault.

The invention provides an air cathode and a microbial fuel cell. The air cathode comprises a catalyst layer, a current collection layer and a diffusion layer, wherein the catalyst layer is made of nitrogen-doped carbon. Thus, through nitrogen-doped carbon, the embodiment of the air cathode is low in cost and efficient in catalysis and can play a better role in a neutral system of the microbial fuel cell.

The invention relates to an application of a composite membrane in a neutral system zinc-iron flow battery. A porous membrane, which is prepared from one or more of organic polymer resins, is taken as the matrix, and a compact membrane, which is made of cationic polymer resin, is compounded on the surface of the porous membrane to prepare the composite membrane. Compared with the original porous membrane, the composite membrane has a higher hydrophilic performance and stronger ion selectivity, can effectively solve the problem of migration of electrolyte solution, prolongs the circulation life of batteries, and improves the performance of batteries, and at the same time, the production cost of the composite membrane of the flow battery is reduced.

The invention discloses a small current fault line selection protection system of a power grid isolated neutral system. In a typical system which adopts a post-set arc suppression coil controller and a small current fault line selection device which are separate from each other, the system is additionally provided with a grounding overvoltage relay and a time relay. The coil of the grounding overvoltage relay is connected with an open delta voltage signal output end of a busbar potential transformer. The normally open contact of the grounding overvoltage relay is serially connected with the coil of the time relay and then is powered by an external power supply. The normally open contact of the time relay is serially connected between a signal input end of the small current fault line selection device and the open delta voltage signal output end of the busbar potential transformer. The system staggers the dynamic compensation process of a post-set arc suppression coil and process of the small current fault line selection capturing a ground fault, so that the small current fault line selection device is enabled to carry out fault line selection after arc suppression coil compensation residual current is stable, the motion correctness of the small current fault line selection device is improved further, and wrong selection and selection leakage are avoided.

The invention discloses a small current grounding line selection device CT polarity error judgment method. The method comprises the following steps that when a grounding fault occurs, a fault branch zero sequence current is determined based on a fault line selected by a device; instantaneous values of all branch currents are recorded by the device sampling wave recording function; and all instantaneous values of all branch currents are calculated and compared, if prescriptive features are not met, branch CT polarity error exiting is determined, line selecting result is not reliable, and the condition is displayed on the device. Based on the premise that isolated neutral system small current grounding line selection device adopts zero sequence CT to obtain zero sequence currents of brancheson a bus, and with combination of the line selection results of the line selection device, the conclusion of whether zero sequence CT inverse connection in the branch existing is obtained through analysis and calculation of characteristics of each branch current when the single-phase grounding fault occurs in the branch.

The invention relates to a laundry detergent containing polylysine and chitosan. The laundry detergent contains the polylysine and the chitosan, wherein the weight ratio of the polylysine to the chitosan is 1:(5 to 35); the laundry detergent also contains citric acid by which the pH value of the laundry detergent is weakly acidic or neutral. According to the laundry detergent disclosed by the invention, the polylysine and the chitosan are combined and the dose ratio of the polylysine to the chitosan is optimized, so that the chitosan enhances sterilization effects of the polylysine on gram-positive bacterium, gram-negative bacterium and mould under the action of amino group, and particularly the long-effect sterilization effect of the laundry detergent is improved; further, a proper amount of the citric acid is added into the laundry detergent, and a stable weakly acidic-neutral system is formed by a balancing effect of the citric acid; the damage of the laundry detergent to clothes is reduced while a suitable action environment is provided for the polylysine and the chitosan; in addition, the flexibility of the clothes can be kept well, and original colors and textures of the clothes can be retained. The laundry detergent provided by the invention is comprehensive in effect and extremely-high in market promotion value.

The invention relates to a control method for a neutral system with distributed time delay based on an interval two-type T-S model. The method firstly determines a mathematical model of a chemical reactor of the petroleum refinery, secondly converts the mathematical model into an interval two-type T-S fuzzy model, designs a T-S fuzzy controller by the parallel distributed compensation method, finally determines a stability condition of the interval two-type T-S fuzzy system, and transforms the stability condition into a linear matrix inequality to obtain a control gain. The control method provided by the invention utilizes the interval two-type T-S model to describe the chemical reactor refining process in the petroleum refinery, and the interval two-type T-S fuzzy set has advantages overthe one-type fuzzy set in the processing system uncertainty, and at the same time has lower computational complexity than the two-type fuzzy set. Therefore, modeling the system using functions of theinterval two-type fuzzy set not only makes the system description more accurate, but also makes the control method more efficient.

The invention discloses a positioning method for single-phase earth fault sections of an isolated neutral system. The method comprises the following steps: firstly, collecting synchronous stable zero sequence current instantaneous values at two ends of the previous section of a to-be-detected line; calculating the difference value of the two synchronous stable zero sequence current instantaneous values; and determining the fault position regions by virtue of the polarity of the difference value and polarities of the two zero sequence current instantaneous values. The method disclosed by the invention can be used for positioning the fault regions for the condition that a transitional resistance is relatively great and the change of length of the line is inconsistent in the system and has a low requirement on the precision of equipment, so that the accuracy of positioning the fault regions is improved.

The invention provides a capacitive current test method, device and system. The method comprises the steps that the primary side of an electromagnetic voltage transformer is electrically connected with the a-phase end, the b-phase end and the c-phase end of a switch cabinet live indication device; the high frequency voltage module of the capacitive current test device outputs the preset abnormal frequency current signal; the test module acquires the abnormal frequency voltage of the secondary side of the electromagnetic voltage transformer under the abnormal frequency current signal; and the total ground capacitance and the ground capacitive current of the isolated neutral system can be calculated according to the abnormal frequency voltage, the abnormal frequency current and the capacitance of the live indication sensor. The abnormal frequency signal is injected and measured by ingeniously using the open delta of the electromagnetic voltage transformer so as to have the characteristics of high safety, high anti-interference capacity and convenient measurement in comparison with the method of direct signal injection. The method is simple in test loop and high in safety without power outage so as to be suitable for the ungrounded system capacitive current test.