Cool storage supervisory controller

• US 4,916,909 A
• Filed: 12/29/1988
• Issued: 04/17/1990
• Est. Priority Date: 12/29/1988
• Status: Expired due to Fees

• Current Assignee: Electric Power Research Institute
• Original Assignee: Electric Power Research Institute
• Inventors: Zhao, Jianliang, Gabel, Steven D., Spethman, Donald H., MacArthur, Ward J., Taracks, Donald, Mathur, Anoop
• Primary Examiner(s): Wayner, William E.
• Application Number:
  US07/291,734
• Time in Patent Office: 474 Days
• Field of Search: 165/18, 62/59, 62/185, 62/201, 364/505
• US Class Current: 62/59
• CPC Class Codes: F24F 11/00 Control or safety arrangements
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/47 Responding to energy costs
• CPC Class Codes: F24F 11/52 Indication arrangements, e.g. displays
• CPC Class Codes: F24F 11/56 Remote control
• CPC Class Codes: F24F 11/64 using pre-stored data
• CPC Class Codes: F24F 11/83 by controlling the supply of heat-exchange fluids to heat-exchangers
• CPC Class Codes: F24F 2005/0025 using heat exchange fluid storage tanks
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: F24F 2140/50 Load

Abstract

A system for controlling the HVAC system of a building to reduce overall electrical costs is disclosed. The system develops an energy usage and storage strategy which is a function predicted ambient temperatures, predicted building load requirements and the power company'"'"'s rate structure.

Claims

1. For a building having a HVAC system which includes chiller means, pump means, storage means, heat exchanging means and a chilled water loop between said chiller means, storage means, and heat exchanging means, an operating method for a cool storage supervisory controller for controlling the HVAC system where the controller includes a direct digital controller, a first control interface between said direct digital controller and said chiller means, a second control interface between said direct digital controller and said pump means, a third controller interface between said direct digital controller and said ice storage means, computing means including data input means, data storage means, memory means, display means, and processing means and a two-way data transfer gateway for communication between said computing means and said direct digital controller, the operating method comprising the steps of:

(a) operating the computing means to determine the predicted ambient temperatures from a projected high temperature and projected low temperature input by the user, historical data of actual temperatures from the current and previous cycles stored by the storage means, and an array of shape factors which assume a daily temperature pattern can be established by each hour'"'"'s position relative to high and low temperatures;

(b) operating the data input means to receive data including predicted building load requirements and power company rate structure information; and

(c) determining a new shape factor by operating the computer means to;

(i) calculate temperature charges for the preceding cycle,

(ii) test these changes for reasonableness,

(iii) if reasonable, calculate current shape factors using the temperatures from the previous cycle and the temperature changes,

(iv) determine whether the current shape factors are reasonable, and

(v) if reasonable, calculate a new shape factor profile from the previous and current profiles using weighted averages; and

(d) operating the direct digital controller to implement a charge/discharge strategy for the storage means where the strategy is a function of the predicted ambient temperatures, the predicted building load requirements and the rate structure information.

2. The method of claim 1 wherein the computer means is operated to calculate new shape factor profile from the previous and current shape factor profiles according to the formula

3. The method of claim 1 wherein the computing means is operated to predict ambient temperatures determined hourly.

4. The method of claim 1 wherein the computing means is operated to determine building load requirements using a clockwise recursive regression computer algorithm.

5. The method of claim 1 wherein said computing means is operated to determine predicted building load requirements from a cooling load profile and a non-cooling load profile.

6. The method of claim 5 wherein the computing means is operated to determine the cooling load profile from historical cooling load data stored in the storage means and the predicted ambient temperature profile for the next day.

7. The method of claim 6 wherein the computing means is operated to determine cooling load profile as a function of pull down requirements after weekend and holiday schedules as well as any other periodic effects on load.

8. The method of claim 1 wherein said charge/discharge strategy is a function of a comparison of the relative costs of direct cooling verses storage for each rate period.

9. The method of claim 1 wherein the HVAC system includes established set points and the charge/discharge strategy is a function of the established setpoints.

10. The apparatus of claim 1 wherein the charge/discharge strategy depends upon the amount of charge available during the remainder of the current cycle.

11. The method of claim 1 wherein the charge/discharge strategy depends upon the mandatory charge.

12. The method of claim 1 wherein the charge/discharge strategy depends on a plurality of economic tradeoffs.

13. The method of claim 1 wherein the direct digital controlled is operated to control the charge and discharge of storage using the charge/discharge strategy.