A method and an apparatus are presented which enable the identification of a capacitor fault in a given string of a capacitor bank, based on the computation of the string impedance by measuring the string AC current and voltages, where each string includes a plurality of capacitor elements connected in series. The method consists of measuring the string capacitive impedance and comparing this value with a previously measured capacitive impedance of the same string. If a difference between these two values is obtained, which exceeds a given threshold for a certain duration, a fault is recorded.

A method can be used to control a flexible interconnection device that includes a number of converters. The method includes receiving a plurality of voltage signals indicating respective voltages of a plurality of load branches and a plurality of current signals indicating respective currents of the plurality of load branches, determining reference active power values for each of the plurality of converters based on the plurality of voltage signals and a plurality of reference voltage signals, determining reference reactive power values for each of the plurality of converters based on the plurality of voltage signals, the plurality of reference voltage signals and the plurality of current signals, and controlling the plurality of converters based on the determined reference active power values and the determined reference reactive power values.

An online voltage control method for coordinating multi-type reactive power resources is provided. First, a linearized power flow equation of branch reactive power is established, and an online voltage control model of multi-type reactive power resources including an objective function and constraint conditions is constructed. The constrain conditions includes generator reactive power constraints, reactive power compensator constraints, transformer tap position constraints, a nodal reactive power balance constraint, and slack contained nodal voltage constraints. Then, an optimization result of voltage control is obtained by solving the model. The method makes full use of reactive voltage operation characteristics of a power grid, constructs a practical online solution model for reactive voltage control of large power grid of coordinating multiple reactive power resources, and under a condition of acceptable accuracy loss, takes in account safety of power grid operation, economy of reactive power resource actions and high reliability of online operation.

It is desirable to improve the accuracy of voltage control in the grid interconnection device for supplying the power generated by the distributed power source to the interconnection point. Provided is a grid interconnection device for supplying power generated by a distributed power source to an interconnection point, comprising: a calculation unit for calculating voltage at the interconnection point based on output voltage of the grid interconnection device, output current of the grid interconnection device, and an impedance component between the grid interconnection device and the interconnection point; and a control unit for controlling output power from the grid interconnection device, based on voltage at the interconnection point calculated by the calculation unit.

Provided in the present invention are a microgrid control system and a microgrid, the microgrid control system comprising: a grid-connected switch, an energy router, a first controller and a second controller; the first controller controls the grid-connected switch and sends a first control instruction; the second controller receives the first control instruction and responds to the first control instruction for controlling the energy router.

The present innovations control and improve operation of one or more microgrids optionally and/or intermittently coupled to an Electric Power System(s).

A microgrid power flow monitoring and control system is described herein. The control system may determine active and reactive power sharing shortage on the electric power delivery system. The control system may utilize the control strategies of generation units, such as ISO control, droop control and constant power control to estimate power flow within a microgrid or other isolated system. A control strategy of one or more generators may be modified based on the determined power flow.

The invention provides systems, methods, and devices relating to the provision of system-wide coordinated control voltage regulation support in power transmission and distribution networks using multiple inverter based power generation or absorption facilities, which are coupled to the power transmission and distribution networks for minimizing transmission and distribution line losses and for performing Conservation Voltage Reduction. The invention uses a novel control method of inverter based Distributed Generators as Static Synchronous Compensator (STATCOM) in a way that provides a dynamic voltage regulation/control with the inverter capacity remaining after real power generation or absorption, thereby decreasing system line losses and performing Conservation Voltage Reduction.

A device for reactive power compensation in a high-voltage network contains a phase conductor. A high-voltage connection is provided for each phase of the high-voltage network. Each high-voltage connection is connected to a first high-voltage winding which surrounds a first core portion and to a second high-voltage winding which surrounds the second core portion. The core portions are part of a closed magnetic circuit. The low-voltage ends of each high-voltage winding can be connected to at least one saturation switching branch configured to saturate the core portions and has actuatable power semiconductor switches controlled by a control unit. To manufacture the device inexpensively, each saturation switching branch has a two-pole submodule having a bridge circuit and a DC voltage source so that, depending on the actuation of the power semiconductor switches, the DC voltage source can either be connected in series to the high-voltage winding or can be bridged.

A system, method and apparatus for an interactive dynamic interface for wireless distributed capacitor control that comprises a touchscreen display that eliminates the conventional dials and switches that are part of a conventional control, and with these efficiencies can locally, remotely or autonomously implement “personality” settings for the capacitor control that speeds and simplifies custom configurations and recovery in relation to user, electrical and environmental input that meets certain operating criteria, including after a shut-down event, thereby improving the of the capacitor control system to function more appropriately, effectively, and efficiently under a greater range of parameters.