81results about How to "The calculation process is clear" patented technology

The invention discloses a three-phase load flow calculation method of a weak looped distribution network comprising multi-type distributed power sources. Firstly, the effective three-phase load flow calculation method of a weak looped distribution network is put forward in a distribution sequencing network based on a sequence component calculation method and in combination with characteristics of the weak looped distribution network and a loop analysis of a road. Secondly, detailed formula derivation of iterative computation of distributed generation (DG) of a PQ node type, a PQ (V) node type, an OV node type and a PI node type is conducted and the easy formula is introduced into the load flow calculation method. The three-phase load flow calculation method of the weak looped distribution network comprising the multi-type distributed power sources can effectively process multi-type DG and the weak looped distribution network and is distinct in calculation procedure, simple in programming, and easy to achieve. In addition, the three-phase load flow calculation method of the weak looped distribution network comprising the multi-type distributed power sources retains strong points of rapid calculation and stable convergence of a forward-back substitution method catering to branch circuits. Finally, effectiveness and good convergence of the three-phase load flow calculation method of the weak looped distribution network comprising the multi-type distributed power sources is tested and verified by means of a IEEE (institute of electrical and electronic engineers)-37 generatrix test calculation case, and the three-phase load flow calculation method of the weak looped distribution network comprising the multi-type distributed power sources has good ability of processing the multi-type DG and the looped network.

The invention discloses a three-phase decoupling load flow calculation method of a power distribution network based on a path matrix. The method comprises the following steps: firstly, adopting a symmetrical component method to perform sequence component decoupling on a three-phase unbalanced power distribution network to obtain zero sequence, a power distribution sequence network with positive sequence and negative sequence, and adopting a loop-analysis method based on the path matrix to perform one-phase-sequence component load flow calculation to obtain load flows of the three-sequence networks; and secondly, transforming sequence network load flows in a phase component mode by an inverse transformation principle of the symmetrical component method to obtain three-phase load flows. By using the method, a three-phase unbalanced power distribution network system is decoupled into zero sequence, positive sequence and negative sequence networks, so that large matrix manipulation in the three-phase load flow calculation is avoided, the calculated amount is decreased, and the calculation efficiency is improved. The method has the advantages of clear calculation process, simple programming and fast calculation speed. Finally, a 6-busbar test example verifies the correctness and good convergence; and the method is good in generality and practical applicability.

The invention discloses a three-phase decoupling power flow calculation method for a power distribution network containing multiple transformer branches. According to the characteristics of basically symmetrical three-phase line parameters, unbalanced three-phase load and the tree structure of the power distribution network, the method comprises the following steps: performing sequence component decoupling on the three-phase unbalanced network of the power distribution network by a symmetrical component method; in a power distribution three-sequence network model, transforming the transformer branches into the common branches by a phase transformation technology; and calculating the sequence network power flow of the power distribution system by a path matrix-based loop analysis method and transforming sequence component power flow into phase component power flow by an inverse transformation principle so as to realize three-phase decoupling power flow calculation of the three-phase unbalanced system of the power distribution network containing multiple transformer branches and reduce calculated quantity. The method is clear in calculation process, simple in programming and high in calculation speed. The correctness and high convergence property of the method are verified through 34 bus test calculation examples. The method has high generality and practicability.

The invention discloses a distributed generation power distribution network three-phase load flow calculation method taking a phase sequence mixing method into consideration. The distributed generation power distribution network three-phase load flow calculation method comprises the following steps that firstly, a power distribution network three-phase load model, a network phase sequence parameter model and a distributed power supply access model are built based on the phase sequence mixing method, an effective three-phase unbalance power distribution power network improved load flow calculation method is disclosed in a power distribution sequence network, and a sequence component method is fully utilized to process the advantages that a three-phase unbalance system has access to symmetrical distributed generation (DG) and PV nodes; and then PQ, PQ(V), PV and PI node type DG calculation models are deduced in detail and are induced into the discloses load flow calculation method. The distributed generation power distribution network three-phase load flow calculation method taking the phase sequence mixing method into consideration has the advantages of being clear in calculation process, simple to program, quick in calculation speed and good in convergence. Finally, the effectiveness and generality of the distributed generation power distribution network three-phase load flow calculation method are tested and verified through diffset. The distributed generation power distribution network three-phase load flow calculation method has good convergence and strong capacity of processing DG nodes and generating reactive power boundary cross.

The invention discloses a method for calculating the power flow of a radial power distribution network based on variable substitution. The method comprises the following steps of: firstly, converting 2/3 of unbalance equations into linear equations in power flow calculation by using variable substitution according to the special topological structure and characteristic of the radial power distribution network, wherein the other 1/3 of unbalance equations are also relatively simple; then, because nonzero elements of a jacobian matrix formed by an unbalance equation set are relatively fixed, respectively calculating the invariant elements and a small number of variable elements of the jacobian matrix by using a sparse technique, wherein the invariant elements do not need to be repeatedly calculated, and a calculation formula of the variable elements is also relatively simple; and finally, carrying out iteration solving on the unbalance equation set to obtain the power flow of the system. The calculation speed and efficiency of a power flow algorithm are improved foundationally through the variable substation and the sparse technique; and the method has the characteristics of clear calculation process, easiness for programming and the like. Finally, the effectiveness and efficient calculation capability of the method are proved through a plurality of test cases.

The invention relates to an evaluation method of transformer substation grounding grids. The evaluation method comprises the following steps: (1) deriving the thinning speed of metal thickness of a grounding grid by applying the faraday's law; (2) determining the minimal section area Sg of a grounding wire without considering corrosion; (3) determining the minimal section area Sg2 when considering the influence of the corrosion factor; and (4) determining the evaluation years of the grounding grid. According to the method, the calculation process is clear, the accuracy rate is high, and the theoretically powerful support is provided for the safety running of a power system grounding grid.

The invention provides an urban traffic health indicator system evaluation method based on the complex network theory. The method mainly comprises the following steps: A: establishing a reliability indicator R of an urban traffic network; B: establishing a brittleness indicator B of the urban traffic network; C: establishing an elasticity indicator S of the urban traffic network; based on obtainedactual urban traffic operation data, importing seepage analysis to calculate the size of a functional sub-group of the urban traffic network under a given threshold, and establishing the reliabilityindicator R of the urban traffic network; mining a key road in the urban traffic network, analyzing a road set collapsing the functional sub-group of the urban traffic network to a certain proportion,and establishing the brittleness indicator B of the urban traffic network; and finally, establishing the elasticity indicator S of the urban traffic network through a whole process of generation-evolution-dissipation. The establishment of the urban traffic health indicator system can provide a support for the assessment of the actual operation state of the urban traffic, the development of targeted traffic management measures, and the improvement of the urban traffic health.

The invention discloses an optimization method for an industrial circulating water system. The optimization method comprises the following steps: 1, carrying out field measurement on the inlet and outlet temperature and the mass flow-rate of a cooling medium and a cooled medium in a heat exchanger in the circulating water system, and the input energy of water supply equipment; 2, according to themeasurement data, determining the optimal mass flow-rate of the cooling medium in each heat exchanger, and according to the height difference and the temperature of the least favorable point of the system, determining the optimal pressure of the system; and 3, according to the obtained optimal mass flow-rate of the cooling medium and the obtained optimal pressure of the system, estimating and calculating the savable energy of a pump house by using an energy consumption balance method to determine whether the equipment is replaced or not, and if the savable energy is more than 5% of the input energy, considering the reconfiguration of the equipment. According to the optimization method, the optimal water supply amount and the necessary minimum pressure can be accurately calculated and the system is controlled to reach the requirements, the energy can be saved for the circulating water supply equipment, the running life of the system can be prolonged, and the production process is more reasonable.

The invention discloses a self-reduction multi-loop centralized predictive control system for reheat steam temperature of a secondary reheat unit. The system is composed of a flue gas recirculation fan rotation speed control loop and a flue gas damper opening degree control loop. The deviation of the primary reheat steam temperature and the secondary reheat steam temperature from a set value is sent to a predictive controller. The optimized values of the flue gas recirculation fan rotation speed and the flue gas damper opening degree are calculated to ensure that the primary reheat steam temperature and the secondary reheat steam temperature of the unit are maintained within a reasonable and safe range. According to the invention, predictive control is used to easily handle the optimization of a large inertia multivariable system; the calculation process is clear and simple; during engineering application, programming is easy to implement; the corresponding control amount can be adjusted in time for the prediction of future output deviation; the primary reheat steam temperature and the secondary reheat steam temperature are stable within a reasonable range, which ensures the stability and safety of the unit; and the control system has a better control effect than traditional PID control.

The invention discloses a thermal power generating unit distributed coordination control system based on multi-parameter dynamic matrix control. The control system comprises a load control loop, a main steam pressure control loop and a separator temperature control loop, load, main steam pressure and separator temperature as well as deviation of a set value are sent to a prediction controller based on a dynamic matrix control algorithm, optimization values of steam turbine regulating valve opening degree, coal feed and water feed flow are acquired by calculation, and tracking performance of a unit to load instructions and running safety performance of the unit are ensured. The optimization problem of a multi-variable system can be processed conveniently by adopting dynamic matrix control, and the calculation process is clear and simple; during engineering application, programming is convenient to implement; corresponding control quantity is adjusted timely by predicting future output deviation, actual generating power can quickly track the load instructions, stability of the main steam pressure and the separator temperature can be ensured, and the unit is high in stability. The control scheme has control effect better than that of conventional PID control.

The embodiment of the invention discloses an installation method of a stay cable of a cable-stayed bridge reduced-scale test model. The method comprises the steps of building a cable-stayed bridge reduced-scale finite element model and a stay-cable-free cable-stayed bridge reduced-scale test model according to the bridge parameters; obtaining the cable force tension value of each stay cable in a cable-stayed bridge according to the bridge forming state requirement of the cable-stayed bridge and the reduced-scale finite element model of the cable-stayed bridge; and installing the stay cables according to the cable-stayed bridge reduced scale test model without the stay cable and the cable force tension values. The method is not limited to a single expected value, different design requirements can be met, the calculation process is concise and clear, the tensioning steps are clear, only the tension information of one cable needs to be paid attention to each time of tensioning, and the complex step that overall optimization cable adjustment is conducted after all stay cables are tensioned, is avoided.

The invention discloses an active power distribution network harmonic source positioning analysis method. The method includes the following steps that according to the characteristics of an active power distribution network, network parameters and measurement data of various fundamental waves and harmonic waves are obtained; then voltage of fundamental waves of all nodes of the active power distribution network and voltage of sub-harmonic waves of the all nodes of the active power distribution network are worked out through a fundamental wave and harmonic wave state estimation method; currents of fundamental waves of all branches of the active power distribution network and currents of sub-harmonic waves of the all branches of the active power distribution network are worked out respectively according to voltage of the fundamental waves of nodes at the two ends of each branch, voltage of the sub-harmonic waves of the nodes at the two ends of each branch and branch parameters; finally, through the relationship formula of branch currents and node injection currents, node injection fundamental wave currents of each node and node injection sub-harmonic wave currents of each node are worked out, the distribution situation of current total harmonic distortion of all nodes of the active power distribution network is worked out further, therefore, distribution positions of all harmonic sources can be positioned accurately, and the characteristics of the harmonic sources are analyzed. The active power distribution network harmonic source positioning analysis method has the advantages that multiple harmonic sources of the active power distribution network are positioned accurately, the calculation process is clear, and programming is easy.

The invention belongs to the technical field of power system planning, and particularly relates to a wind-thermal bundled power generation system optimization planning method. The minimum total bundled system cost including the operation cost, the investment and the maintenance cost serves as an objective function, the minimum startup and shutdown and the maximum output and the minimum output of a thermal power unit and the like serve as constraint conditions, a wind-thermal bundled power generation system optimization planning model including a system operation behavior is built, and the model is solved by adopting algorithms such as dynamic planning and a tree drop technique. On the basis of simulating the operation behavior of the bundled system and in consideration of the operation constraints of the thermal power unit, the operation cost of the thermal power unit can be acquired more accurately, and the wind-thermal capacity planning result in the bundled system is more accurate and more reasonable.

The invention discloses a photovoltaic generated power forecasting device and method. The invention relates to the technical field of photovoltaic power generation. The photovoltaic generated power forecasting device comprises a PM10 (Particulate Matter) sensor, a PM2.5 sensor, a humidity sensor, a visibility sensor, a temperature sensor, a RS232 (Recommend Standard) communication interface, a single chip, a power circuit, a clock circuit, a 3G (The 3rd Generation Telecommunication) communication module, a FPGA (Field Programmable Gate Array) chip and a FLASH chip. Based on acquiring a large number of actual samples of PM2.5 concentration-PM10 concentration-humidity-visibility-AOD (Aerosol Optical Depth), the power forecasting method forecasts the AOD by using a BP (Back-Propagation) neural network method; the AOD and the precipitable water are selected as main change parameters; the two-band atmospheric radiation transmission model is adopted to calculate the solar direct radiation intensity and the scattering radiation intensity; thus, the total radiation intensity received by the photovoltaic cell panel is forecasted; at last, the photovoltaic generated power is precisely forecasted in real time through the photovoltaic conversion model; the output power of the photovoltaic power generation is forecasted; and the method is advantaged in clear calculation process and high forecasting precision.

The invention discloses a method for determining the grade of a single-bus trip-out loss of load accident in a double-bus connection mode. The method identifies the voltage loss of a transformer station caused by the trip-out through network analysis, and measures the shedding load of a stability control device caused by the trip-out by power flow analysis, and determines and analyzes the grade ofa loss of load accident in combination of the results in the two previous aspects. The method is clear in calculation process, simple in structure, convenient to operate, and good in practicality, and can provide reference and basis for scheduling operation risk assessment. According to the inventive idea, the present invention also provides a system for determining the grade of a single-bus trip-out loss of load accident in a double-bus connection mode.

The invention discloses a safety constraint unit combination rapid calculation method and system based on model dimension reduction. The method comprises the steps as follows: performing calculation to obtain an active power output result of each unit and a power flow result of each power transmission section according to a preset safety constraint economic dispatching relaxation model; dividing generator units into must start and stop units and buffer units according to the active power output result of each generator unit; dividing the power transmission sections into valid sections and invalid sections according to the power flow result of each power transmission section; obtaining a safety constraint unit combination dimension reduction model by taking the start-stop state of the buffer units as a combination decision variable and considering the limit value constraint of the valid power transmission sections; and performing calculation to obtain a unit combination result accordingto the safety constraint unit combination dimension reduction model. By identifying invalid shaping variables and network constraints, the feasible region is reduced, and the calculation efficiency is improved.

The invention discloses an electric power spot market clearing calculation method based on multi-strategy fusion dimension reduction, and the method comprises the steps: firstly obtaining a power gridrange and a calculation period for carrying out the clearing calculation of an electric power spot market, and determining a calculation boundary; then carrying out merging analysis of similar time periods, and reducing the number of time periods for entering clearing calculation; establishing and solving a relaxation safety constraint unit combination model, carrying out invalid start-stop variable identification and effective safety constraint identification according to a calculation result, and reducing the number of start-stop variables and safety constraints entering clearing calculation; establishing a time period merged security constraint unit combination dimension reduction clearing model, and quickly solving to obtain a unit combination result; and carrying out full-time-periodeconomic dispatching and safety check analysis based on a unit combination result, adding the out-of-limit time period and the monitoring section into a unit combination dimension reduction clearingmodel, and finally obtaining an electric power spot market clearing result through iterative computation.

The invention provides an improved method for selecting a high-voltage circuit breaker in a power transformation and distribution system, which summarizes a relationship between a periodic component and a direct current component of breaking short-circuit current and improves a calculation formula for the breaking capacity of the circuit breaker. Different from the traditional calculation method, the improved method respectively calculates the periodic component and the direct current component of the short-circuit current and then compares with breaking current of the circuit breaker so as to judge whether the breaking current of the circuit breaker can meet requirements or not. The time-periodic component relationship which is relatively simple and easy to search and calculate is found out by using a relational expression, a value range of a time constant in a power distribution system is deduced, and a calculation method is provided; and the breaking capacity of the circuit breaker is determined through comparing the breaking time. The improved method is simple and clear in calculation process, the original calculation data is easy to obtain, and the calculation result is accurate. Electrical equipment with a high performance-cost ratio can be accurately selected because the accuracy is substantially improved.

The invention discloses an RDE data post-processing method, device and equipment and a storage medium. The method comprises the steps that RDE test data and an emission delay time table of a vehicle are acquired; performing data translation on the RDE test data according to the emission delay time table, screening out RDE calculation data meeting preset requirements, and unifying data formats; dividing time windows according to laws and adjustments, determining an average emission set corresponding to each time window according to the RDE calculation data, and determining an emission test result corresponding to each average emission in the average emission set. The method is suitable for RDE test data acquired by different RDE emission devices. The RDE data post-processing method solves the problem that existing RDE data post-processing software can only process RDE test data collected by specific RDE emission equipment and has limitation, can conveniently and quickly analyze and calculate the RDE test data to obtain a test result, and is clear in calculation process and accurate and reliable in result.

The invention relates to a reactive power compensation method and device for a distributed power supply. The reactive power compensation method comprises the steps of calculating reactive power of a system according to acquired current and voltage of the system; acquiring a reactive power regulation value which the system is supposed to have in order to enable the reactive power of the system to approach to the set value according to a set value and the reactive power of the system; and calculating reactive power of a distributed power supply branch according to acquired current and voltage of the distributed power supply branch. Compensation is performed on the reactive power of the system, and the voltage and current of the system are acquired in real time to act as feedback values so as to perform real-time regulation, and a closed-loop control system for the reactive power of the system is formed. When reactive power compensation is performed on the system, a reactive power compensation value for the system is enabled to be the difference between a reactive power regulation value of the system and the reactive power of the distributed power supply branch, so that variations in reactive power of the distributed power supply branch are balanced through regulating the reactive power compensation value for the system in real time, reactive power compensation can be performed quickly, and thus voltage fluctuations of the system are suppressed.