A frequency support system arranged for providing frequency support to an AC grid. The system includes an ES arrangement, and a bi-directional DC/AC power electronic converter interface configured for connecting the ES arrangement with the grid. The ES arrangement includes a plurality of series connected ES groups, each ES group including a plurality of parallel connected ES modules, each ES module including an energy storage interfaced by a bi-directional power electronic ES converter configured for connecting the ES with a DC side of the converter interface.

A system (100) for generating electricity comprising - at least one structure (1) defining an upper support surface (11) and a lower support surface (12); - a plurality of cranes (2, 2a, 2b, 2c, 2d, 2e) adapted to move a plurality of bodies (3) from the upper support surface (11) to the lower support surface (12), and vice versa; wherein each crane (2, 2a, 2b, 2c, 2d, 2e) is provided with - gripping means (21 ) adapted to grasp a body (3) of said plurality of bodies (3); - and a device (4) connected to the gripping means (21), adapted to transform into electricity the kinetic energy of a body (3) grasped by the gripping means (21 ), which moves, in particular substantially vertically, under the effect of gravity towards the lower support surface (12).

A flywheel includes a hub configured to rotate about a longitudinal axis. At least one member having a laminate casing connected to the hub, the laminate casing is formed with an enclosed space for housing at least one mass with a fixed shape. The enclosed space is structured to control radial displacement of the at least one mass. Wherein upon rotation, an operational radial force applies a through thickness laminate radial load to the laminate casing, while simultaneously radially displacing the at least one mass to apply a controllable compressive load on the laminate casing. The applied controllable compressive load increases a predetermined laminate loading capacity by an amount of compressive load counteracting the through thickness laminate radial load, resulting in a corresponding increase in a flywheel angular velocity, that therefore increases an amount of energy stored by the at least one energy storage unit.

This disclosure describes novel hybrid energy storage systems for providing short-term and long-term storage and delivery of electricity generated by any energy source including renewable energy sources such as solar energy and wind energy. The hybrid energy storage systems described herein have a higher overall real-world efficiency than energy storage systems currently available.

A stored energy power source uses a wound-rotor induction machine (WRIM) to receive energy from a prime mover via a rotating shaft, provide magnetization reactive energy from a self-excited AC capacitor bank, store the energy in N energy storage elements (ESEs) via tertiary windings, and discharge the ESEs to deliver energy via a secondary winding to a load producing output. Each discharging ESE contributes to a total flux at the secondary winding to sum the individual ESEs voltages. These voltages can be stepped up or down by a transformation ratio between the secondary winding and each of the tertiary windings. A flywheel may be coupled to the shaft to store and delivery kinetic energy. Load factor power control can be used to stabilize the output voltage. The source may be configured to allow for the bi-directional flow of energy between the ESEs, the flywheel and the load. The WRIM provides a safe, reliable and efficient system to provide high-level AC and DC output voltages.

A kinetic energy recovery system with flywheel includes a cascade flywheel doubly-fed electric machine and an electric motor. The cascade flywheel doubly-fed electric machine has a stator end coil, a rotor end coil and a flywheel. The flywheel can store kinetic energy by increasing speed or releasing kinetic energy by decreasing speed. A control circuit has an inverter, a rectifier and a DC bus connecting the inverter and the rectifier. The inverter supplies alternating current to the rotor end coil. The rectifier has an AC end connected to the stator end coil through an AC bus. The rectifier converts alternating current to direct current, so that the inverter can draw power from the DC bus. The electric motor has a phase coil connected to the AC bus. When the cascade flywheel double-fed electric machine decelerates, the system converts mechanical energy into electrical energy.

Heat energy storage systems described in this disclosure can be used for long-term storage of large amounts of thermal energy. In some cases, such systems receive electrical energy from renewable energy sources such as solar panels or wind turbines. Using novel techniques, the heat energy storage systems covert the electrical energy to thermal energy that is stored in hot materials such as molten silicon, molten salts, or any other material that can store large amounts of heat. The heat energy storage systems incorporate extremely good thermal insulation of the thermal energy storage tank that contains the hot materials. The systems are also configured to release thermal energy in an efficient manner to an electricity-producing steam turbine using novel heat exchanger systems and techniques that are described. The energy storage systems described herein have a higher overall real-world efficiency than energy storage systems currently available.

A power transfer system includes a series of energy storage modules (ESMs) or energy storage devices (ESDs) that are coupled together to be able to transfer power between one another, as well as receive power from a power source, such as an onshore power generator. The energy storage modules may be hybrid energy storage modules, each including an electrical-machine-inertial energy store and an electro-chemical energy store. The energy storage modules are configured to receive constant-current DC or AC input from the power source, and are able to provide constant-current and constant-voltage output, either sequentially or simultaneously. The power transfer system allows the modules to operate independently or in conjunction with one another, should some of the connections of the system be broken. The energy storage modules may be used to provide power to underwater systems, for example sonar systems, weapons systems, or underwater vehicles.

A charging system which charges a power storage device mounted on a moving object, includes: an electric power conversion device that converts electric power supplied from a commercial power supply; a kinetic energy storage device that stores kinetic energy; and a rotary electric machine that is electrically connected to the electric power conversion device and is mechanically connected to the kinetic energy storage device.

A power system includes a base, two magnetic bearings mounted on the base, a shaft rotatably mounted on the two magnetic bearings, a flywheel mounted on the shaft, a motor connected with the flywheel, an uninterrupted power supply electrically connected with the motor, a utility power electrically connected with the uninterrupted power supply, a coupling connected with the shaft, a speed change device connected with the coupling, a generating device connected with the speed change device, a load electrically connected with the generating device, a recharge rectifier electrically connected with the uninterrupted power supply, and a reactor electrically connected with the recharge rectifier and the generating device. Thus, the enlarged torque of the flywheel provides the inertia power to enhance the generating power of the generating device.