Control system and method for limiting power demand of an industrial plant

• US 3,872,286 A
• Filed: 10/12/1973
• Issued: 03/18/1975
• Est. Priority Date: 10/12/1973
• Status: Expired due to Term

• Current Assignee: Richard E.J. Putman
• Original Assignee: Richard E.J. Putman
• Inventors: Putman, Richard E. J.
• Primary Examiner(s): Botz, Eugene G.
• Assistant Examiner(s): Wise, Edward J.
• Application Number:
  US05/406,067
• Time in Patent Office: 522 Days
• Field of Search: 235/151.21 324/103 307/52 444/1
• US Class Current: 705/412
• CPC Class Codes: G06Q 50/06 Energy or water supply
• CPC Class Codes: H02J 2310/60 Limiting power consumption in the network or in one section of the network, e.g. load shedding or peak shaving
• CPC Class Codes: H02J 2310/64 The condition being economic, e.g. tariff based load management
• CPC Class Codes: H02J 3/14 by switching loads on to, or off from, network, e.g. progressively balanced loading
• CPC Class Codes: Y02B 70/3225 Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier
• CPC Class Codes: Y04S 20/222 Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y04S 50/10 Energy trading, including energy flowing from end-user application to grid

Abstract

The invention relates in general to control of the consumption of energy derived by an industrial user from a power supply system (electrical, gas or like commodity), and more particularly to a control system for adjusting an industrial load system to limit the demand of power while respecting the constraints of the load system.

Claims

1. In a control system for holding to a demand limit at the end of a billing period the power demand of an industrial plant having a plurality of interruptible loads, including means for providing an indication of power consumption of said loads during a billing period;

means responsive to said means for providing an indication of power consumption for predicting a demand at the end of said billing period;

means responsive to said demand predicting means for providing a demand error relative to said demand limit;

means for selecting a suitable amount of power;

comparator means responsive to said demand error providing means and to said power selecting means for establishing a residual error relative to said demand limit; and

means responsive to the output of said comparator means for load control;

the combination of;

means for setting switching constraints to at least part of said loads thereby to define among said interruptible loads and at times during said billing period, loads of controllable status and loads of non-controllable status;

said load control means including means for switching a load of a switchable amount of power in response to the sign of the output of said comparator means;

means for indicating the switching status of said loads at anytime during said billing period;

said power selecting means including priority means operative with a priority list of loads of controllable status and in accordance with the output of said switching status indicating means;

said power selecting means being operative in response to said residual error during successive decision periods within said billing period to provide a switchable amount of power from said priority list;

said switching means being operative in response to said power selecting means during such said decision period and operative in response to said constraint setting means before such said decision period; and

, wherein said demand predicting means is responsive to operation of said constraint setting means before any such said decision period.

2. The control system of claim 1 with means for establishing said residual error relative to a biased said demand limit, said comparator means being selectively operable relative to said demand limit and to said biased demand limit;

wherein said comparator means and said switching means are operated relative to said biased demand limit during a first period within said billing period and wherein a predetermined priority load is selected by said priority means during a second period following said first period;

with said comparator means and said switching means being operated relative to the unbiased said demand limit during said second period.

3. The control system of claim 1 with means for preventing operation of said switching means during an initial period of said billing period;

with means for establishing a bias to said demand limit during an inteRmediary period following said initial period; and

with means for reducing said bias progressively to zero during a final period following said intermediary period and ending with said billing period.