68results about How to "Achieving power balance" patented technology

The invention discloses a control strategy for restraining circulating currents of three-phase four-leg inverters on the basis of third-harmonic injection, and provides a method for restraining circulating currents of three-phase four-leg inverters on the basis of third-harmonic injection. The method includes that three-phase current reference signals outputted by voltage loops are synthesized into a zero-sequence current reference signal (4) on the basis (1) of parallel-connection voltage and current double-loop control of the three-phase four-leg inverters for a parallel-connection topology of two three-phase four-leg inverter modules (2) and (3), and error amplifiers track the zero-sequence current reference signal for a mid-line inductive current in a fourth leg of each module, so that mid-line currents of the two three-phase four-leg inverters are shared, and purposes of restraining the circulating currents of the mid-line currents, protecting power tubes and improving the efficiency of each inverter are achieved; and output signals of current loops of the two modules are synthesized to form two third-harmonic signals (5), the two third-harmonic signals (5) are added to obtain a sum (6), an average value (7) of the sum is used as a common third-harmonic signal (8) for being injected into three-phase and mid-line modulation signals of the two inverter modules, zero-sequence modulation components in the third-harmonic signals are eliminated, and the instantaneous zero-sequence circulating currents caused by factors such as inconsistency of parameters of a main circuit filter and inconsistency of switching time of switching tubes are restrained. The method has the outstanding advantages that the circulating currents of the mid-line currents are effectively restrained; control loops are simple; and third-harmonic injection of the parallel-connection inverters is unaffected, and the direct-current voltage utilization rate is increased.

The invention discloses an alternating current / direct current distribution network distributed optimization method considering wind power uncertainty. Based on the natural partitioning properties of an alternating current / direct current distribution network, a typical alternating current / direct current hybrid distribution network structure and distributed optimization framework are established. Within each alternating current / direct current power grid sub-region, the 1-norm and the infinity-norm are considered at the same time to constrain the probability distribution of each wind power outputscene, and a data-driven two-stage distribution robust model is established. The model uses the electricity purchasing cost of a superior power grid, the electricity purchasing and selling cost of alternating current / direct current sub-regions, the wind abandonment cost, the power generation cost of a micro-turbine and the like as optimization goals, and uses the 1-norm and the infinity-norm to constrain the uncertainty of the probability distribution of the screened typical scene. The data-driven two-stage distribution robust model is established, and column and constraint generation algorithms are used to solve.

The invention brings forward a power balancing control method of cascaded photovoltaic grid-connected inverter on the partial shadow condition. The method comprises the following steps: (1), carrying out independent maximum power point tracking (MPPT) controlling on H bridges of all cascade units to obtain all-stage direct-current voltage instruction values and then carrying out PI controlling on a general direct-current voltage to obtain a grid-connected current instruction value; (2), carrying out quasi-proportional resonant (PR) control of the grid-connected current and grid voltage feedforward control so as to obtain initial duty ratio values of the H bridges; (3) carrying out per-unit processing on actual values of the direct-current side voltages of the cascade units according to the respective direct-current side voltage instruction values of all the cascade units, carrying out comparison with 1 and carrying out PI controlling so as to obtain active correction values of the duty ratios of the H bridges, and realizing power balancing control based on the duty ratio correction. According to the control method, floating control of the grid-connected current can be realized; and power balancing of all power units of the cascade inverter can be maintained. The provided control method has advantages of clear conception, simple control structure, and easy engineering realization and the like.

The invention discloses a battery discharge balancing method. The method includes (1) judging discharge demand; (2) calculating storage battery property; (3) calculating bidirectional DC / DC converterperformance; (4) forming a pairing relation. According to the invention, through calculating the storage battery property and the bidirectional DC / DC converter performance, automatic power balance ofthe battery in the discharge process is realized and balancing effectiveness is ensured.

The invention discloses a novel double-drum balanced driving device and a using method. The device comprises a PLC control system, a slide block mechanism, a carrier roller and a material bearing box, wherein the PLC control system comprises a torque sensor, a rotating speed sensor, a motor, a hydraulic pump and a hydraulic cylinder; the torque sensor and the rotating speed sensor are connected to a drum shaft; the motor is connected to the hydraulic pump, and the hydraulic pump is connected to the hydraulic cylinder; the slide block mechanism is fixed on a fixed rack between the two drums and is driven by the hydraulic cylinder to move up and down; the roller is mounted on a carrier roller groove on the slide block mechanism; the material bearing box is arranged right below the carrier roller between the two drums for loading sundries falling from a carrier roller sweeping conveyor belt. The device disclosed by the invention realizes power balance driven by the double drums, reduces imbalance of abrasion of the two drums, and achieves the purposes of reducing the loss and prolonging the service lives of the drums and the conveyor belt.

The invention discloses a charging station locating and sizing method and device. The method comprises the following steps: establishing a traffic network model for calculating road traffic flow in real time according to traffic network data based on a graph theory method, wherein the traffic network data comprises at least two road nodes, longitude and latitude coordinates of the road nodes, a road node connection relationship and the number of electric vehicles among the road nodes with the connection relationship; establishing a traffic flow space-time transfer model based on the road traffic flow and the environment temperature; and achieving information interaction between the traffic network model and the traffic flow space-time transfer model based on the speed, traffic flow and traffic flow density relationship in the traffic network model and the traffic energy consumption relationship in the traffic flow space-time transfer model, predicting the charging load, and determiningthe installation position and capacity of the charging station according to the charging load. The charging load simulation result is closer to the actual load, the installation position and the required capacity of the charging station are accurately determined according to the charging load, and power supply balance is achieved.

The invention provides a dynamic economic dispatch distributed optimization method and system for a smart power grid, and the method comprises the steps: measuring the frequency of each node, and calculating the Lagrange multiplier deviation; updating the Lagrange multiplier at the current moment based on the consistency algorithm and the Lagrange multiplier deviation corresponding to the generating capacity at the previous moment; and updating the generating capacity and the charging and discharging power in the X update and performing judging, and if the conditions are met, performing Y updating on all nodes. On the basis of a neural network controller, the variable quantity of a Lagrange multiplier is calculated through frequency deviation, so that power balance in a power grid is realized, and a novel thought is provided for realizing power balance constraint in an economic dispatching problem.

The invention discloses a battery management system and method. The battery management system comprises a standby battery module, a plurality of switch modules and a controller, wherein the switch modules are in series connection between the standby battery module and a plurality of battery modules in a battery pack, and the controller is used for detecting the voltage value of the battery modules in the battery pack and controls closing and opening of a specific switch module according to the charging and discharging state of the battery pack in order to connect a corresponding battery module in the battery pack with the standby battery module in parallel. The battery management system is provided with the standby battery module, enables the specific battery module in the battery pack to be charged or discharged according to the charging and discharging state of the battery pack, achieves electric quantity balance of the battery pack in the charging and discharging process, and is simple, reliable and low in cost.