536 results about "Load loss" patented technology

The invention belongs to a risk evaluation method for the operation of a large power grid. The method comprises the following steps of (1) statistics of fault and risk factors; (2) computation of risk probability; (3) risk quantitative evaluation based on the load loss; (4) classification and result evaluation on risk index. According to the risk evaluation method for the operation of the large power grid, the occurring probability of power system accidents and the number of load loss of the system are combined to form a new quantitative index, so a scheduling person can be helped to perform real-time risk evaluation and analysis, can further comprehensively master the safe operation condition of the power grid, and controls the risk level of the system within a reasonable range by adopting necessary measures, and the occurrence of the disaster fault is avoided. The real-time evaluation and management and control on the risk are realized by a power gird scheduling center and the method belongs to a load loss-based risk evaluation method for the operation of the large power grid.

The invention discloses a circuit cluster-based method for analyzing a grid cascading failure, belonging to the technical field of safety protection of a power system. The method comprises the following steps of: applying a Bayes network failure tree theory to cascading failure analysis based on a distribution failure probability model of a self-critical circuit cluster and establishing a probability analysis model for a grid cascading failure based on cascading failure probability analysis of the self-critical circuit cluster in combination with the probability characteristic of a cascading failure developing stage; and through simulating a cascading failure process, performing risk assessment on the cascading failure by using a system load loss index and analyzing weak links of a system. By adopting the method, foundations are provided for a prevention strategy for further research on the reduction of cascading failure risk.

The invention discloses a concrete tensile creep testing device which comprises a bracket, an upper perforated-articulated chuck, a lower perforated-articulated chuck, a perforating test piece, a deformation gauge and a balance weight load, wherein the two perforated-articulated chucks which are connected with the perforating test piece are respectively hung on the bracket and are connected with the balance weight load, so that the testing device can be formed. A concrete shrinkage stress creep testing method adopts a standard creep chamber and natural environmental condition, is restrained by complete or non-complete constraint stiffness, adopts loading ways of 'step loading' and 'follow-up loading', is carried out under the shrinkage threshold value and fixed age period loading control condition, and can be used for testing the concrete shrinkage stress creep. After the testing device and the testing method are adopted, the problems of connection between the concrete test piece and the chucks, physical alignment and load loss can be solved, and the test operability can be improved; furthermore, creep and strain can be tested gradually, so that more creep behaviors and performance problems can be researched; particularly, the concrete shrinkage stress creep test can be realized in the natural environment.

The invention discloses a method for evaluating the electric power system risk based on fault pre-scanning. The method comprises the steps that firstly, according to the current structure of an electric power system and a planning scheme, a corresponding planning scheme model is established; secondly, based on device data and a power grid structure, predicted faults and the possibility of the predicated faults of a power grid are analyzed, and then a pre-scanning fault set is formed; thirdly, through the risk state based on direct-current power flow, screening and ordering are conducted on the predicated fault set, so that a fault state list is formed; fourthly, all power flow corresponding to the faults in the list is worked out, and for the fault with the power flow out of range, the consequence of the fault is load loss; fifthly, according to the load loss of the fault states and the possibility of the fault states, the system risk indicator is worked out; sixthly, according to the system risk indicator, the system weak link is found out. By the adoption of the method for the evaluating electric power system risk based on fault pre-scanning, analysis of all the fault sates in the fault set through alternating-current power flow is avoided, so that the calculation amount of follow-up alternating-current power flow analysis and risk indicator processing is greatly reduced, and a large mount of calculation time is saved.

The invention discloses a method for evaluating the power system static risk based on hybrid power flow. The method comprises the steps that (1) according to the current structure of a power system and a planning scheme, a corresponding planning scheme model is established; (2) according to equipment data and the structure of a power grid, predicated faults of the power grid and the possibility of the predicated faults are analyzed, and then a predicated fault set is established; (3) the power flow corresponding to all the faults in the predicated fault set is worked out through the risk state based on the hybrid power flow, and for the fault with power flow out of range, load loss is used as a fault consequence; (4) according to the load loss of the fault states and the possibility of the fault, the system risk indicator is worked out; (5) according to the system risk indicator, the weak link of the system is found. According to the method for evaluating the power system static risk based on the hybrid power flow, the problem that when high-order fault occurs in a large complicated power grid, misconvergence of power flow is caused due to the fact that only alternating-current power flow is applied during risk evaluation is solved through the hybrid power flow.

The invention relates to an electric power system net rack reconstruction optimization method capable of considering a microgrid as a black-start power supply. The method comprises the following stepsthat: inputting electric power system parameters; taking the maximum recovery of the power generation capacity of the system and the minimization of a load loss amount in the microgrid as targets toconstruct a net rack reconstruction optimization model capable of considering the microgrid as the black-start power supply; determining the constraint condition of the net rack reconstruction optimization model capable of considering the microgrid as the black-start power supply; on the basis of a node importance degree and path recovery time, constructing a synthesis path evaluation index to optimize the recovery path of a unit to be recovered; and jointly combining a bee colony algorithm with a quantum theory to solve the model. A net rack reconstruction strategy which adopts the microgridwhich contains high-ratio renewable energy sources as the black-start power supply has certain feasibility and effectiveness. Under a situation that the conventional black-start resources of the system are insufficient, the microgrid can be taken as the black-start power supply to provide starting power for non-black-start units, and the non-black-start units can be quickly recovered to achieve apurpose of net rack reconstruction.

A synchronous induced wind power generation system is provided, comprised of a horizontally rotatable turbine-generator section that wind vanes into the prevailing wind direction. The turbine-generator section has a horizontally disposed turbine shaft therein, and air induction shrouds at either end thereof, the anterior areas of the air induction shrouds having larger areas than the interior area of the turbine-generator section, so as to induce a larger differential air pressure across the turbine. The turbine is directly coupled to a synchronous AC generator that is synchronized with an external power line in connection therewith, and directly generates synchronous AC power. Further, turbine magnetic brakes and/or adjustable pitch directrix blades are employed to control the speed of rotation of the turbine 1) during synchronization with the electrical line, 2) to modulate turbine power, and 3) to protect against overspeed during high wind and loss of load.

The invention discloses a probability assessing method for a stage type protection operational risk of an electric power system, and the probability assessing method belongs to the field of the relay protection of the electric power system and the reliability of the electric power system. The probability assessing method comprises the following steps: determining a protection system to be assessed and a false action source set; carrying out invalidation classification analysis on the protection system to be assessed; calculating the instantaneous false action probability of a protection element in the false action source set in a new electric network structure and in a power flow state; if the false action of the protection system in the false action source set also cuts off a line where the false action is positioned, carrying out N-2 power flow calculation to obtain load loss corresponding to a current faulty line; calculating the instantaneous non-startup probability of the protection element in the false action source set and the load loss caused by a remote backup action; calculating the risk indicator, the total instantaneous false action probability and the total instantaneous non-startup probability of the protection system to be assessed; and judging a weakest protection link in the electric network. The probability assessing method has the beneficial effects that the principle characteristic of protection is reflected, and the action rejection probability, the false action probability and the corresponding operational risk of the protection can be quantitatively calculated.

The invention relates to a sweeping and twisting type three-dimensional blade diffuser. According to the structure, the front edges of blades are designed into a sweeping shape, the sweeping angle ranges from -45 degrees to 45 degrees, and the blades are suitable for incoming flow and are twisted to be expanded into different air flow angles. The main blade is designed into a three-dimensional integral structure from an inlet to an outlet in the axial direction. The flow-dividing blades are arranged on the rear section in a main blade channel. The sweeping and twisting type three-dimensional blade diffuser has the advantages that interaction of shock waves and a boundary layer is relieved, so that flow in the diffuser is modified; blade surface air flow separation and load loss which are caused by a relative large positive/negative attack angle in part of the blades in the high portion are eliminated, flow loss is reduced, and therefore a stator part diffuser of a centrifugal/oblique flow gas compressor can reach the higher efficiency and the larger pressure ratio. The strength of the shock waves is changed and the shock waves are even eliminated and influence caused by interaction of the shock waves and the boundary layer is relieved; flow loss caused by the overlarge positive attack angle or the overlarge negative attack angle is avoided, the expansion capacity and the operation range of the diffuser are improved, and therefore the improvement in the performance of the whole-level gas compressor is assisted.

A power distribution network N-1 calibration method taking segmental load transfer into consideration comprises the following steps: carrying out initial analysis of a lattice structure; carrying out simplification analysis of the lattice structure; analyzing circuit transfer analysis; carrying out N-1 calibration and load loss calculations of a circuit and N-1 calibration and load loss calculations of a main transformer respectively, namely, carrying out load segmental cutting sequentially when N-1 calibration and N-1 calibration of the circuit and the main transformer do not pass, and carrying out load transfer capability analysis of the main transformer, load transfer analysis of an interconnection unit of a transformer station, overload transfer correction of the main transformer, and transfer capability calculation of the network of the transformer station sequentially; carrying out load segmental cutting when N-1 calibration and N-1 calibration of the circuit and the main transformer does not pass. The calibration method has the advantages that the power distribution network N-1 calibration result can be higher under the premise that the calculation accuracy is guaranteed; load is cut when a calibration result does not pass, so as to facilitate improvement of calibration level of power distribution network power supply safety, and more accurately guide analysis and selection of planning, reformation and running method of a power distribution network.

The invention discloses an asymmetric half-bridge converter and a control method thereof. A one-way clamping network is additionally arranged and is connected in parallel with a primary side, a secondary side or a third winding of a transformer, an auxiliary switch is controlled to be switched off when an excitation inductance current reaches a set value, the one-way clamping network is conducted,a clamping current passes through the one-way clamping network, the clamping current is clamped and maintained to be basically unchanged by the one-way clamping network, the one-way clamping networkis controlled to be switched off within a certain time before a main switch is conducted, the clamping current is released, voltages of two ends of the main switch are reduced to zero or be approximate to zero, and zero-voltage conduction of the main switch is achieved. By the asymmetric half-bridge converter, effective control of negative peak of the excitation inductance current can be achieved,a current effective value of a power device under light load of a converter is reduced, the light-load efficiency of the converter is substantially reduced under the condition that the advantages ofzero-voltage conduction of an existing technical scheme is maintained, the no-load loss is reduced, and control implementation is simple and efficient.

A wind-photovoltaic-energy-storage power generation system capacity optimizing method based on a wind-photovoltaic hybrid characteristic belongs to the technical field of a wind-photovoltaic-energy-storage power generation system. According to the wind-photovoltaic-energy-storage power generation system capacity optimizing method, through controlling the hybrid power generation system, island-mode operation and grid-connected-mode operation of the hybrid power generation system can be realized. According to the wind-photovoltaic-energy-storage power generation system capacity optimizing method, a capacity optimizing model which is suitable for the wind-photovoltaic-energy-storage power generation system is presented, wherein system cost minimizing is used as an optimizing target, and furthermore the wind-photovoltaic hybrid characteristic, a grid-connected power fluctuation condition and a system load loss rate are comprehensively considered. The wind-photovoltaic-energy-storage power generation system capacity optimizing method has advantages of sufficiently utilizing the wind-photovoltaic hybrid characteristic, ensuring high reliability in power supplying of the system just through a relatively low storage battery capacity, and reducing system cost.

The invention relates to a dynamo using slot wedge using compound soft magnetic powder magnetic conductance material. The powder is the compound soft magnetic powder compounded from MnZn ferrite powder and reduced iron powder or carbonyl iron dust. The radio is 10-90wt% high resistivity magnetic powder, and 10-90wt% high magnetic permeability magnetic powder. Adding certain quantity glass fiber into compounded magnetic powder layer, separating structure would be formed. The invention could decrease supplementary load loss of dynamo, as well as eddy current loss, and improve efficiency of dynamo.

The invention discloses a method for predicting the relaxation life of a spiral spring on the basis of the stress relaxation theory of a temperature accelerating material. The method comprises the following steps of: testing stress relaxation data of the spiral spring at test temperature and drawing a relaxation curve; drawing a semilogarithmic curve of load loss rate and time and fitting a regression equation; drawing a relation curve of relaxation factors A and B and temperature and fitting a regression equation; and calculating relaxation factors A (actual) and B (actual) of the spiral spring at an actual use temperature and calculating the relaxation life of the spiral spring. Compared with the traditional compression loading and unloading method, the method has the advantages that due to adoption of an RDL10 spring stress relaxation testing machine, errors are reduced and the accuracy is improved; and since a temperature accelerating mode is adopted for predicting the relaxation life of the spiral spring, the predication accuracy is higher, simultaneously the test period is greatly reduced, the efficiency is improved and the cost is lowered.

The invention provides a control circuit and a control method with self-adaptive blanking time. The blanking time control circuit generates a blanking control signal according to current peak value of a main switch; the blanking control signal is used for controlling the blanking time in a feedback voltage signal sampling process, so that the blanking time can be changed along with the change of the current peak value of the main switch tube. According to the control circuit and the control method with the self-adaptive blanking time, accurate feedback and sampling can be realized without causing wrong detections; and in addition, the blanking time can be well controlled by the circuit according to actual changes, and the no-load loss is reduced.

The present invention relates to an oil-immersed transformer overtemperature warning method under a harmonic condition. The method comprises a step of determining any harmonic current distribution and the transformer winding eddy current loss, transformer stray loss and transformer total load loss actual values of a same total current effective value, a step of determining the relation among a transformer load loss, a harmonic distortion rate and a load rate, a step of determining the relation among a transformer hottest point temperature rise, the harmonic distortion rate and the load rate, and a step of determining the threshold of a corresponding alert level. According to the method, through transforming the basic formula of the transformer harmonic loss, the relation among the harmonic loss, a harmonic current distortion rate and the load rate is obtained, thus according to the relation model between transformer temperature rise and loss, the temperature rise condition of a transformer after a certain time is derived, and the early warning of the transformer temperature rise is realized.

The invention discloses an apparatus for large-scale oil-immersed transformer no-load and on-load comprehensive tests and a method. The apparatus is composed of a test power source part and a measurement system. The test power source part includes an induction regulator, an intermediate transformer, an oil-immersed intensive compensation capacitor bank and a test control system which are successively connected via a circuit. The measurement system includes a precision measurement current transformer, a voltage transformer and a power analyzer. The apparatus can conduct on-site no-load and on-load loss measurement tests on 110-kV and 220-kV voltage class transformers, and can complete measurements of no-load current, no-load loss, no-load harmonic waves, short circuit impedance and load loss of transformers, and can automatically calculate the measurement test results of no-load and load loss.

The invention provides a power grid load loss risk assessment method based on a PSASP model and an emergency power supply automatic throw-in strategy. The method includes the steps of extracting a node card, a branch card and a virtual branch card of a PSASP load flow calculation model, establishing a mapping relation between emergency power supply automatic throw-in device action logic and the PSASP load flow calculation model, establishing an emergency power supply automatic throw-in device strategy simulation model configuration table and conducting power grid power supply load loss risk simulation assessment. According to the method, the problem that power grid power supply load loss risk cannot be accurately assessed in power grid operation research and analysis work is solved, previous power grid fault simulation analysis modes are changed, a powerful technological support is provided for simulation analysis work of faults of a power grid N-1, a power grid N-2, important transmission sections and the like, and power grid potential safety hazard checking and controlling are analyzed more accurately and effectively.

The invention provides an interconnected power grid cascading fault risk assessment and alarming method considering communication vulnerability degrees. Unified empirical extreme values are constructed separately for the sending delay, propagation delay, queue delay and link utilization rate of communication links; normalization processing, zero suppression processing and equal weight addition areperformed, so that the vulnerability degrees of the communication links of the same standards under different time cross sections are obtained; and the vulnerability degrees of communication nodes are constructed through using the node degree-based performance vulnerability degrees, service routing matrix-based topological vulnerability degrees, and business criticality degrees of the communication nodes. With the communication vulnerability degrees are considered, the outage probability model of branches at all levels of an interconnected power grid is established; load loss quantities, voltage fluctuation degrees, average communication link utilization rates and communication unobservable rates are defined as the consequence indicators of cascading fault paths; and the cascading fault paths are sorted and assessed, and a variety of alarms are given out. According to the interconnected power grid cascading fault risk assessment and alarming method considering communication vulnerability degrees of the invention, power risk assessment and communication vulnerability are combined together, so that the fault analysis and control of an interconnected power grid wide-area measurementand control system can be more comprehensive and reasonable.

The invention discloses a power system risk assessment method taking into consideration rainfall-induced landslide geological disasters. The method comprises the following steps: estimating the cumulative rainfall capacity of a rainfall-induced landslide disaster and the deflection of transmission tower deformation caused by landslide mass according to the data information of rainfall and the geological data information around transmission towers; getting the joint probability distribution of transmission tower damage by means of curve fitting; forming a 'weather-power network-grid' integrated layer based on a gridding technology, calculating the number of effective transmission towers corresponding to transmission lines covered by rainfall, and calculating the failure probability of the transmission lines; sampling the transmission lines through a non-sequential Monte Carlo method to get the load loss state of the system; calculating the amount of system load shed under the load loss state of the system based on an optimal load shedding model of AC power flow; and finally, doing statistics of the risk indicators of the system.

The invention discloses a generator and a control method for load adjustment based on an optimization model. By establishing an objective function and a model, an overloading branch power flow is reduced by adopting the mode of adjusting the output of the generator or the mode of adjusting the generator and controlling the load shed; and the purpose of greatly shortening the optimal solution process of the searching is achieved by a simplified method of the optimization model and the solving strategy flow of the model. Combined with the online real-time measurement ability of WAMS, after the control measure in each step is adopted, the quantity of the WAMS is measured as feedback information to form a closed loop control mode so that the normal operation of a grid can be reasonably ensured to recover under the condition of control cost and load loss so as to achieve the purpose of eliminating the inter-tripping of circuit branches caused by overloading, and can be suitable for the dynamic changeable process after a circuit branch cutting event occurs in the grid.

The invention discloses a reactive compensation method and device having a transformer reactive current real-time compensation function and belongs to the field of electric energy quality control. The reactive compensation method and device are used for conducting real-time calculation on the no-load loss and the loss (changing along with the load rate) in the load-available condition, real-time compensation of reactive current of a transformer is achieved, and the problem that the power factor is low due to the reactive loss of the transformer is solved. Meanwhile, the optimal control theory is used for calculating the switching strategy of capacitance compensation of an SVG and a TSC, switching of the SVG and the TSC can reach the optimized effect, and the advantages of fastness and nonpolarity are achieved completely.

The invention discloses a large synchronous camera group running-down simultaneous connection method. The method comprises the following steps: a SFC device is used to drag the camera group; when therotational speed of the camera group is accelerated to 1.05 times of the rated rotational speed, the SFC device exits, and the excitation system boosts voltage; The adjuster set is subjected to mechanical friction, the effect of no-load loss and excitation loss of main transformer, As that rotate speed decreases gradually, the monitor system sends a synchronization instruction to the synchronization device after detecting that the terminal voltage rise to the set value, and the synchronization device detects the voltage on the waiting side and the grid side for real-time calculation, capturesthe connection opportunity in the idle process of the unit, and sends out the connection circuit breaker closing instruction when the synchronization condition is judged to be met; After detecting theswitching-on signal of the grid-connected circuit breaker, the synchronous device feeds back the synchronous success signal of the monitoring system, and the grid-connected success is achieved at thesame time. The invention can realize fast and reliable grid connection of the synchronous camera group, and has guiding significance for the synchronous grid connection of other similar idle-type equipments.

The invention relates to a distribution transformer, in particular to an arcless on-load volume regulation and voltage regulation distribution transformer, which comprises a transformer body, an on-load volume regulation high-voltage combination switch, an on-load volume regulation low-voltage combination switch, a three-phase on-load voltage regulation combination switch and a distribution transformer monitoring judgment unit, wherein the transformer body is used for arcless on-load volume regulation and voltage regulation operation, energy transmission and voltage transformation, the on-load volume regulation high-voltage combination switch and the on-load volume regulation low-voltage combination switch are used for volume gear shift, the three-phase on-load voltage regulation combination switch is used for high-voltage gear shift, and the distribution transformer monitoring judgment unit is used for monitoring, judging and controlling the on-load volume regulation high-voltage combination switch, the on-load volume regulation low-voltage combination switch and the three-phase on-load voltage regulation combination switch. The arcless on-load volume regulation and voltage regulation distribution transformer provided by the invention has the advantages that the no-load loss of the distribution transformer is effective reduced, the power supply voltage quality of users is improved, the operation management efficiency of a distribution station zone is improved, and in addition, the goal of improving the reliable and economic operation level of the distribution station zone is reached.