A method for controlling a virtual generator including at least one renewable power source, an accumulation system including a power and/or energy reserve, an inverter and a control law, the virtual generator delivering an active P/reactive Q electrical power of voltage V and of current I to a microgrid, the voltage V and current I having a frequency f, the active P/reactive Q electrical power controlling, via droop control, the frequency f and the RMS voltage V.sub.rms of the voltage V, respectively, the method including control of the virtual generator via the control law for which it carries out an adjustment of the active P/reactive Q power delivered to the microgrid, the adjustment being capable of compensating for a variation in the active/reactive power consumed by the microgrid.

Distributed static synchronous series compensators (DSSSCs) which may also be designated tower routers capable of injecting series inductive or capacitive impedances to enable distributed power-flow control. When a large number of these (a fleet of) DSSSCs are distributed over the grid for power-flow control, it is necessary to ensure that coordinated communication and control capabilities are also established, enabling fast reaction to changes that can exist across the grid. A system architecture and method for enabling localized high-speed low-latency intelligent control with communications between subsections (local network) of the grid along with communication to the central Grid operations center at the utility for supervisory control is disclosed herein. The architecture provides sub-cyclic (< 1/60 of a second) response capability, using the local DSSSCs with high-speed communication at the local network level to power-system disturbances, such as power-oscillation damping (POD), sub-synchronous resonance (SSR) etc.

The present disclosure provides a DC power supply system and its control method. The system includes: a first power supply circuit and a second power supply circuit, at least one of the first power supply circuit and the second power supply circuit including a phase shifting transformer, wherein the first power supply circuit includes a number N of first AC/DC conversion circuits, and the second power supply circuit includes a number N of second AC/DC conversion circuits, where N is an integer greater than or equal to 2; an output side of each of the N first AC/DC conversion circuits is electrically connected in parallel with an output side of a corresponding second AC/DC conversion circuit of the N second AC/DC conversion circuits through a DC busbar to form N sets of redundant backup circuits.

A starting and stopping method for a static synchronous series compensator (SSSC) is provided. A starting process includes: first, connecting a converter (4) to a shunt transformer (2), and closing an incoming line switch (1) of the shunt transformer to charge the current converter until a direct-current voltage is stable; then, opening the incoming line switch of the shunt transformer, and connecting the converter to a series transformer (5) through a change-over switch (3); deblocking the converter, and controlling a current of a bypass switch (6) of the series transformer to approach zero; further, opening the bypass switch of the series transformer, and enabling the converter to enter a normal operation mode after a line is stable; and in stopping the SSSC, first, switching a control mode of the converter to make the current of the bypass switch approaches zero when closed the bypass switch, then controlling a current of the series transformer to be gradually reduced to zero to make the series transformer out of service, and then blocking the converter. By means of the method, an overvoltage and an overcurrent of a converter when a series transformer is put into use and exits can be effectively suppressed, and current oscillation of an line and impact on the series transformer can be reduced, thereby achieving stable starting and stopping of an SSSC.

A connecting device for connecting two n-phase alternating voltage grids of the same frequency includes n susceptance elements each having continuously variable susceptance values. Through the use of each susceptance element, two connecting conductors, which are associated with one another, of the alternating voltage grids can be connected to one another and the active power exchange between the AC voltage grids can be controlled by varying the susceptance values in a targeted manner. A method for operating the connection device is also provided.

Systems and methods for supplying power (both active and reactive) at a medium voltage from a DCSTATCOM to an IT load without using a transformer are disclosed. The DCSTATCOM includes an energy storage device, a two-stage DC-DC converter, and a multi-level inverter, each of which are electrically coupled to a common negative bus. The DC-DC converter may include two stages in a bidirectional configuration. One stage of the DC-DC converter uses a flying capacitor topology. The voltages across the capacitors of the flying capacitor topology are balanced and switching losses are minimized by fixed duty cycle operation. The DC-DC converter generates a high DC voltage from a low or high voltage energy storage device such as batteries and/or ultra-capacitors. The multi-level, neutral point, diode-clamped inverter converts the high DC voltage into a medium AC voltage using a space vector pulse width modulation (SVPWM) technique.

The present invention proposes a hybrid converter branch operating mode for a Modular Multilevel power Converter MMC with MMC cells in distinct subsets operating according to a “pulse blocked” cell operation mode with DC cell voltage increase or according to a “bypass” cell operation mode without DC cell voltage increase. Repeated cell subset assignment and corresponding alternation of cell operating mode allows to reduce or at least manage a mean deviation of the cell capacitor DC voltages of the converter cells. The invention also reduces no-load losses of the MMC in standby mode and a charging voltage in an MMC charging mode.

The present invention provides a power control circuit connectable to a load adapted to receive a power supply, the power control circuit adapted to absorb power from the power supply and adapted to deliver power to the power supply to stabilize at least one electrical parameter of the power supply. The present invention also provides an associated method of stabilizing at least one electrical parameter of a power supply connectable to a load, the method including absorbing power from the power supply or delivering power to the power supply. The at least one electrical parameter of the power supply includes parameters such as voltage and frequency.

A high-voltage hierarchy hundred-megawatt level (100 MW) battery energy storage system and optimizing and control methods are provided. The system includes a multi-phase structure, of which each phase is divided into multi-story spaces from top to bottom. A battery module is provided in each story of the multi-story spaces. The battery module is connected to a DC terminal of an H-bridge converter, and each phase is cascaded by the H-bridge converter. A capacity of the single-phase energy storage apparatus of the present invention is large, and multiple phases can be connected in parallel to form a 100 MW battery energy storage power station. The power station has the advantages of simple structure, easy coordinated control, low control loop model and coupling, and optimal system stability. The control system of the present invention has fewer hierarchies, a small information transmission delay, and a rapid response speed.

The invention provides a method and system for operating a solar farm inverter as a Flexible AC Transmission System (FACTS) device—a STATCOM—for voltage control. The solar farm inverter can provide voltage regulation, damping enhancement, stability improvement and other benefits provided by FACTS devices. In one embodiment, the solar farm operating as a STATCOM at night is employed to increase the connectivity of neighbouring wind farms that produce peak power at night due to high winds, but are unable to connect due to voltage regulation issues. The present invention can also operate during the day because there remains inverter capacity after real power export by the solar farm. Additional auxiliary controllers are incorporated in the solar farm inverter to enhance damping and stability, and provide other benefits provided by FACTS devices.