Data processing: generic control systems or specific application – Specific application – apparatus or process – Electrical power generation or distribution system
Reexamination Certificate
1998-09-29
2001-08-21
Gordon, Paul P. (Department: 2121)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Electrical power generation or distribution system
C700S276000, C700S291000, C700S296000, C700S299000
Reexamination Certificate
active
06278909
ABSTRACT:
FIELD OF THE INVENTION
The present invention is concerned with a method and an apparatus for controlling the amount of power supplied to a conditioning device such as, for example, a heating device acting on the value of a predetermined physical parameter within an area in relation to a setting signal. In the following description, reference will be made to temperature control but the present invention may be also applied to the control of humidity, pressure, or any other physical parameter.
BACKGROUND OF THE INVENTION
Changes in temperature in a house or building tend to be required at specific periods of the day. For example, in a cold environment, the temperature setting is lower for the night and higher at wake-up time. This produces an instant high electrical power demand coming from a multitude of houses around the same time, which results in problems for electricity supply companies.
Known in the art, there is the U.S. Pat. No. 4,228,511 of SIMCOE et al., describing a system and a method for limiting power demand and for temperature control. According to this invention, a room thermostatic control provides for automatic power defer, i.e. modification of load consumption of electrically energized heating and cooling systems during intervals when there is a peak load demand on the electrical supply system. During power defer ambient indoor temperature is controlled by set point adjustment to minimize discomfort, e.g. by pre-boosting, by ramped temperature deferral at controlled rates, and thereafter by ramped recovery at controlled rates to the reference, i.e. desired, temperature. A circuit sensing external conditions, e.g. outdoor temperature, indicative of power defer, is utilized to generate a power defer signal for enabling modification of the set point. Digital signals are stored for each of a plurality of consecutive real time intervals for heating and cooling modes. A real time clock is utilized to access the digital signals for the current time interval. During presence of a power defer signal set point variation is controlled in accordance to the relevant digital signals for each current time interval.
The following patents also describe different systems or methods for power demand control or temperature control: U.S. Pat. Nos. 4,100,428; 4,167,965; 4,228,511; 4,509,585; 4,909,041; 5,095,715; 5,285,963; 5,361,982; 5,501,268; 5,467,812; 5,678,626 and 5,682,949.
A drawback with the systems or methods of the prior art is that although some of them allow a deferring of the power demand when a peak load occurs, none of them is concerned with a method or a system for spreading over a time period and reducing in intensity the amount of power supplied to a conditioning device when a new setting signal is issued.
An object of the present invention is to provide a method and an apparatus for spreading over a time period and reducing in intensity the amount of power supplied to a conditioning device when a new setting signal is issued.
Another object of the present invention is to perform the above-mentioned spreading over a time period and reducing in intensity in a way where the discomfort for the user is controlled and limited.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a method for controlling an amount of power supplied to a conditioning device acting on an actual value of a predetermined physical parameter within an area in relation to a setting signal, the method comprising steps of:
(a) monitoring the setting signal to detect a change thereof;
(b) if the monitoring of step (a) fails to detect the change of the setting signal, controlling the amount of power supplied to the conditioning device to maintain the actual value of the predetermined physical parameter within a range of desired values determined by the setting signal, and returning to step (a); and
(c) if the monitoring of step (a) detects a changed setting signal:
(i) determining a time period and a uniform amount of power required by the conditioning device to cause the actual value of the predetermined physical parameter to theoretically reach a new range of desired values corresponding to the changed setting signal;
(ii) establishing time-related upper and lower limit profiles HLV(t) and LLV(t) of the predetermined physical parameter for the time period determined in step (i), the upper and lower limit profiles HLV(t) and LLV(t) having respectively different starting values and converging toward the new range of desired values at an end of the time period, the actual value of the predetermined physical parameter being included in a range delimited by the starting values;
(iii) supplying the uniform amount of power determined in step (i) to the conditioning device;
(iv) monitoring the actual value of the predetermined physical parameter during the time period in view of the upper and lower limit profiles HLV(t) and LLV(t) to detect when the actual value of the predetermined physical parameter reaches one of the limit profiles HLV(t) and LLV(t);
(v) when the actual value of the predetermined physical parameter reaches one of the limit profiles HLV(t) and LLV(t), controlling the amount of power supplied to the conditioning device to cause the actual value of the predetermined physical parameter to follow substantially the limit profile HLV(t) or LLV(t) that has been reached for a remaining portion of the time period; and
(vi) monitoring time from a beginning of the time period and when the time period ends returning to step (a).
Preferably, the range of desired values is limited to a single desired value, the amount of power supplied to the conditioning device is limited to a maximum power amount, and, in step (i), the uniform amount of power is determined by steps of:
calculating a value A where A=(the single desired value−the actual value);
measuring an actual amount of power supplied to the conditioning device, and calculating a first percentage of the maximum power amount that represents the actual amount; and
calculating a second percentage of the maximum power amount where the second percentage=(the first percentage+(A*a power command error)), the uniform amount of power being determined as the second percentage of the maximum power.
Preferably, in step (ii), the time-related upper and lower limit profiles HLV(t) and LLV(t) are established by steps of:
determining whether the value A is positive or negative;
if the value A is positive, which means that the actual value of the predetermined physical parameter has to be raised, establishing:
the lower limit profile LLV(t) of step (ii) by means of the following equation: LLV(t)=the single desired value−((the time period−&Dgr;t)*(A+a predetermined tolerance margin)/the time period), &Dgr;t representing time elapsed since the beginning of the time period; and
the upper limit profile HLV(t) of step (ii) by means of the following equation: HLV(t)=the single desired value; and
if the value A is negative, which means that the actual value of the predetermined physical parameter has to be lowered, establishing:
the upper limit profile HLV(t) of step (ii) by means of the following equation: HLV(t)=the single desired value−((the time period−&Dgr;t)*(A−a predetermined tolerance margin)/the time period); and
the lower limit profile LLV(t) of step (ii) by means of the following equation: LLV(t)=the single desired value.
Preferably, in step (i), when a first changed setting signal is detected, the time period is determined in relation to a predetermined initialization value, and for each subsequent changed setting signal that is detected, the time period is upgraded by means of the following steps:
calculating the following equation:
the time period=a precedent time period+a gain*(a previous amount of power determined in step (i)−a predetermined fraction of the maximum power amount), where the gain and the predetermined fraction are fixed values determined by previous experimentations; and
comparing the time period with a ra
Couture Roland
Handfield Louis
Thibeault Pierre
Foley & Lardner
Garland Steven R.
Gordon Paul P.
Hydro-Quebec
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