Abstract: A method for obtaining a three-phase power flow of a power distribution network and a device for obtaining a three-phase power flow of a power distribution network are provided. The method comprises steps of: selecting a three-phase power transformer with an ungrounded neutral connection in the power distribution network; correcting a three-phase admittance matrix of the three-phase power transformer; and applying the three-phase admittance matrix to a preset algorithm to obtain a three-phase power flow of the power distribution network.

Abstract: A method and a device for charging an electric vehicle in a power system are provided. The method includes: obtaining a plurality of electric vehicles connected to the power system at a dispatching time, and obtaining a rated charging power and a charging requirement at the dispatching time; determining a charging period corresponding to the plurality of electric vehicles; determining a forecast period, and obtaining a charging requirement, a remaining charging energy capacity and a maximum charging power; establishing a charging model of the plurality of electric vehicles, establishing a first constraint of the charging model, and establishing a second constraint of the charging model; and solving the charging model under the first constraint and the second constraint to obtain an optimal charging power of each electric vehicle at each charging time in the charging period so as to charge each electric vehicle under the optimal charging power.

Abstract: A method and a device for charging an electric vehicle in a power system are provided. The method includes: obtaining a first electric vehicle connected to the power system, and obtaining a rated charging power and a first charging requirement; determining a first charging period corresponding to the first electric vehicle; determining a forecast period, and obtaining a second electric vehicle to be connected to the power system; revising the first charging period to obtain a second charging period, and obtaining a second charging requirement and a maximum charging power; establishing a charging model, establishing a first constraint of the charging model, and establishing a second constraint of the charging model; and solving the charging model under the first constraint and the second constraint to obtain an optimal charging power so as to charge each first electric vehicle under the optimal charging power.

Abstract: A method and a device for identifying a feasibility of a transmission interface constraint in an online rolling dispatching are provided.

Abstract: A method for obtaining a continuous power flow of an electric power system is provided. The method comprises: establishing first power flow equations for PQ buses, and establishing second power flow equations for PV buses; establishing power flow equations according to the first flow equations, the second power flow equations, and a voltage magnitude and a voltage phase of a balance bus; choosing a bus having a fastest voltage drop as a parameterization bus, and defining a parameterization variable according to a voltage magnitude of the parameterization bus and the load growth factor; defining an equality constraint equation according to the parameterization variable, and generating an extended power flow equation according to the equality constraint equation and the power flow equations; solving the extended power flow equation by a plurality of iterations to obtain a plurality of load summations; generating a P-V curve according to the plurality of load summations.

Abstract: A method and a device for navigating an electric vehicle in charging are provided. The method comprises: S1, obtaining a navigation area, wherein the navigation area comprises a plurality of charging stations; S2, receiving a charging request from an electric vehicle in the navigation area; S3, obtaining a plurality of first time periods according to the electric vehicle and the plurality of charging stations; S4, selecting a minimum first time period from the plurality of first time periods; and S5, navigating the electric vehicle to a charging station corresponding to the minimum first time period.

Abstract: Method and system for charging electric vehicles in an aggregation is provided. The method includes: obtaining a plurality of first charge power curves of a plurality of electric vehicles in the aggregation; obtaining a coordinating information of each of the plurality of electric vehicles from the plurality of first charge power curves; obtaining a first feedback charge power curve of each of the plurality of electric vehicles from the coordinating information and a charging cost curve of each of the plurality of electric vehicles; judging whether the first feedback charge power curve is same with the first charge power curve of each of the plurality of electric vehicles; if yes, charging each of the plurality of electric vehicles in accordance with the first charge power curve.

Abstract: A substation-control center tow-level distributed grid nonlinear state estimation method is provided. RTU measurement data and PMU measurement data at each voltage level in each substation are collected. Performing a first three-phase state estimation is performed to obtain a first estimation result. Bad data from the RTU measurement data and the PMU measurement data are removed to estimate a state of a CB. A new CB island at each voltage level is formed, and a second three-phase state estimation for the new CB island is performed to obtain a final estimation result, in which the new CB island is a bus. The final estimation result is processed to obtain ripe data. And the ripe data, a part of the RTU measurement data and a part of the PMU measurement data are collected and a whole grid state estimation is performed.

Abstract: A security and economy coordinated automatic voltage control method based on a cooperative game theory is provided. The method includes: establishing a multi-objective reactive voltage optimizing model of a power system; resolving the multi-objective reactive voltage optimizing model into an economy model and a security model; solving the economy model and the security model based on the cooperative game theory to obtain the automatic voltage control instruction; and performing an automatic voltage control for the power system according to the automatic voltage control instruction.

Abstract: A static security constrained automatic voltage control method is provided, which includes: performing a single automatic voltage control calculation for a control snapshot of a power system in each control cycle. The single automatic voltage control calculation comprises: obtaining a single-time severe contingency sequencing table and a periodical severe contingency sequencing table from a historical severe contingency information database, and selecting severe contingencies; performing a contingency assessment for the active contingency set, and iterating between a result of the contingency assessment for the active contingency set and a solution of the optimal power flow model to obtain a single automatic voltage control instruction; and performing a contingency assessment for a contingency set, and updating the single-time severe contingency sequencing table and the periodical severe contingency sequencing table according to a comprehensive result of the contingency assessment.

Abstract: A method of substation-control center two-level distributed modeling for power grid is provided. The method comprises: (1) building a substation model for each of substations, each substation model comprising a network model having a topological structure of the substation devices, parameters of the substation devices and measurement information of each substation devices, and a wiring diagram of each substation based on a whole line identification consistency; (2) uploading each substation model for each of the substations to the control center through a state power dispatching data network; and (3) splicing network models for the substations according to the wiring diagrams of the substations to build a whole power grid model of a whole power grid so as to monitor and control the whole power grid.

Abstract: A substation-control center tow-level distributed grid nonlinear state estimation method is provided. The method comprises steps of: collecting RTU measurement data and PMU measurement data at each voltage level in each substation; performing a first three-phase state estimation to obtain a first estimation result, and removing bad data from the RTU measurement data and the PMU measurement data to estimate a state of a CB; forming a new CB island at each voltage level, and performing a second three-phase state estimation for the new CB island to obtain a final estimation result, in which the new CB island is a bus; processing the final estimation result to obtain ripe data; and collecting the ripe data and/or a part of the RTU measurement data and a part of the PMU measurement data and performing a whole grid state estimation.