A system includes a computing device that selectively communicates with a self-powered device. The self-powered device has several modes of operation, including a first low-power mode of operation and a second high-power mode of operation. The self-powered device is to communicate with the computing device when the self-powered device is in the second mode of operation. The self-powered device may conserve power by alternating between the first mode of operation and the second mode of operation such that the self-powered device is in the second mode of operation during pre-determined or adaptively-determined time intervals. A duty-cycle of the second mode of operation relative to the first mode of operation may be in accordance with a power budget for the self-powered device.

Self-Powered Devices and Methods

Electric power uses or loads in a premises are controlled or managed depending upon whether the use is for heating, hot water, heat pump, air conditioning, lights, appliances, pumps, etc., according to programs that are controlled by the electric Power Company, for the purposes of spreading power uses at the premises over a day or other time interval, to avoid peak load periods encountered by the Power Company, while still providing the normal comfort levels required by the subscriber from the various power uses. Power levels of several uses at the subscriber's premises are sensed and the power for each use is controlled according to a program that includes a schedule of power level and/or the time of day that is inserted in the program or controlled in the program by the Power Company to accomplish the spreading. In a particular embodiment, a programmed computer unit is provided at the premises that is monitored by the Power Company via the subscribers telephone line. Changes in the computer program are inserted in the unit by the Power Company, via the telephone line; and signals within and throughout the premises for detecting and controlling power uses are transmitted to and from the unit over the premises power line.

Subscriber electric power load control system

A load shedding apparatus for limiting peak electrical demand in an electrical system to a target level through load shedding. The apparatus employs predictive control logic to estimate the amount of energy that needs to be shed in a predetermined future period. Preferably, the load shedding apparatus forecasts the amount of energy require in a predetermined future period by analyzing current energy consumption, current load shedding, and error factors indicative of the random energy demand characteristics of the electrical system. The apparatus estimates the amount of energy that needs to be shed in view of the forecast of the amount of energy required in the predetermined future period. The apparatus selects non-essential loads for shedding until the estimated amount of energy that needs to be shed is reached. The apparatus transmits shed control signals to selected devices within the electrical system to disconnect the selected devices.

Method and apparatus for adaptive demand limiting electric consumption through load shedding

A disk drive is disclosed comprising a disk, a head, a voice coil motor (VCM) for actuating the head radially over the disk (the VCM having a voltage control input), and a spindle motor for rotating the disk, the spindle motor comprising a plurality of windings and a rotor rotatable at a variable spin rate wherein the rotor generates a back EMF (BEMF) voltage across the windings proportional to the spin rate of the rotor. A plurality of switching elements are coupled to the windings, and switch control logic generates switch control signals applied to the switching elements for commutating the spindle motor during normal operation and for generating an internal supply voltage Vi from the BEMF during a spin down mode, the internal supply voltage Vi applied to the voltage control input of the VCM for parking the head. A demand limit circuit disconnects the internal supply voltage Vi from the voltage control input of the VCM when the internal supply voltage Vi falls below a predetermined level, and reconnects the internal supply voltage Vi to the voltage control input of the VCM once the internal supply voltage Vi recharges to a predetermined level, thereby enhancing power management during the spin down mode.

Disk drive comprising a demand limit circuit for enhancing power management during spin down

A method is provided for merging different load forecasts for power grid centers. Area load forecasts are accepted from load forecast engines. A relational database saves load forecast engine data. A comprehensive operating plan integrates individual load forecasts into a composite load forecast to present a comprehensive, synchronized and harmonized load forecast.

Method for integrating individual load forecasts into a composite load forecast to present a comprehensive synchronized and harmonized load forecast

In a power utilization system having loads drawing energy from a utility company, some loads are adjustable and, as part of computerized power demand control system, loads are regulated as well as switched ON or OFF in order to meet an assigned power demand limit. The adjustable loads draw power in accordance with a local supply controller, such as a tap changer, but regulated amounts of power are established by the computer with a set point which is a function of the demand error calculated in an outer loop by the power demand control system and maintained by the computer in a closed loop from an individual power meter and with the established set point. The priority schedule and error computations take into account the amounts of power drawn by adjustable loads as well as the amounts drawn by loads which can be shed, or reconnected.

II Woodward C. Carter

Papers

Load regulation as part of an adaptive priority determination power demand control system