Extremum Seeking Based Control Strategy for a Chilled-Water Plant With Parallel Chillers

2015 ◽  
Author(s):  
Baojie Mu ◽  
Yaoyu Li ◽  
Timothy I. Salsbury ◽  
John M. House
Keyword(s):  
Control Strategy ◽  
Cooling Tower ◽  
Input Saturation ◽  
Extremum Seeking ◽  
Total Power ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Water Plant ◽  
Total Power Consumption ◽  
Chilled Water

Chilled-water plants with multiple chillers are the backbone of ventilation and air conditioning (VAC) systems for commercial buildings. A penalty function based multivariate extremum seeking control (ESC) strategy is proposed in this paper for maximizing the energy efficiency in real time for a variable primary flow (VPF) chilled-water plant with parallel chillers. The proposed ESC algorithm takes the total power consumption (chiller compressors + cooling tower fan + condenser water pumps + penalty terms if inputs saturation occurs) as feedback, and tower fan air flow, condenser water flows and evaporator leaving chilled-water temperature setpoint as plant inputs (ESC outputs). A band-pass filter array is used in place of the conventional high-pass filter at the plant output so as to reduce the cross-channel interference. Chiller sequencing is also enabled with input saturation related signals. A Modelica based dynamic simulation model is developed for a chilled-water plant with two parallel chillers, one cooling tower, one air-handling unit and one zone. Simulation results under several testing conditions validate the effectiveness of the proposed model-free control strategy, as well as the significant energy saving.

A Multivariable Newton-Based Extremum Seeking Control for Condenser Water Loop Optimization of Chilled-Water Plant

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Baojie Mu ◽  
Yaoyu Li ◽  
John E. Seem ◽  
Bin Hu
Keyword(s):  
Power Efficiency ◽  
Cooling Tower ◽  
Water Flow Rate ◽  
Extremum Seeking ◽  
Total Power ◽  
Feedback Signal ◽  
Efficient Operation ◽  
Extremum Seeking Control ◽  
Water Plant ◽  
Chilled Water

This paper presents a multivariable Newton-based extremum seeking control (ESC) scheme for efficient operation of a chilled-water plant. A modelica-based dynamic simulation model of the chilled-water plant consists of one screw chiller and one counter-flow cooling tower was adopted for evaluation of proposed two-input Newton-based ESC controller. The ESC controller takes the total power of the chiller compressor, the cooling-tower fan, and the condenser water (CW) pump as feedback signal and discovers the optimum outputs of cooling-tower fan speed and the condenser-loop water flow rate to maximize the power efficiency in real time with the cooling load being satisfied. Remarkable energy saving is observed for several testing conditions.

A Multi-Variable Newton-Based Extremum Seeking Control for a Chilled Water Plant With Variable Water and Air Flow

2014 ◽  
Author(s):  
Baojie Mu ◽  
Yaoyu Li ◽  
Bin Hu ◽  
John E. Seem
Keyword(s):  
Energy Saving ◽  
Power Efficiency ◽  
Cooling Tower ◽  
Water Flow Rate ◽  
Extremum Seeking ◽  
Total Power ◽  
Extremum Seeking Control ◽  
Model Free ◽  
Water Plant ◽  
Chilled Water

The chilled water system, typically consisting of chiller and cooling tower, plays a major role in the ventilation and air-conditioning systems in commercial buildings. Due to the significant power consumption of such system, improvement of its efficiency would lead to significant benefit in energy saving. As the system characteristics and operational conditions can vary dramatically in practice, model-free self-optimizing control is of high interest in practice. In this study, the chilled-water plant being studied consists of one screw chiller and one counter-flow cooling tower. A multi-variable Newton-based extremum seeking control (ESC) scheme is applied to maximize the power efficiency in real time with the cooling load being satisfied. The feedback for the ESC controller is the total power of the chiller compressor, the cooling tower fan and the condenser water pump, while the inputs are cooling-tower fan speed and the condenser-loop water flow rate. The two-input Newton-based ESC controller is simulated with a Modelica based dynamic simulation model of the chiller-tower system. Two inner-loop PI controllers are used to regulate the temperatures of evaporator superheat and evaporator leaving water at their respective setpoints. Simulation results validate the effectiveness of the proposed control strategy. Remarkable energy saving is observed for several testing conditions.

scholarly journals Noise-Cancelling CMOS Active Inductor and Its Application in RF Band-Pass Filter Design

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
Santosh Vema Krishnamurthy ◽  
Kamal El-Sankary ◽  
Ezz El-Masry
Keyword(s):  
Filter Design ◽  
Low Noise ◽  
Total Power ◽  
Active Inductor ◽  
Cmos Process ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Noise Cancelling ◽  
Total Power Consumption ◽  
Band Pass

A CMOS active inductor with thermal noise cancelling is proposed. The noise of the transistor in the feed-forward stage of the proposed architecture is cancelled by using a feedback stage with a degeneration resistor to reduce the noise contribution to the input. Simulation results using 90 nm CMOS process show that noise reduction by 80% has been achieved. The maximum resonant frequency and the quality factor obtained are 3.8 GHz and 405, respectively. An RF band-pass filter has been designed based on the proposed noise cancelling active inductor. Tuned at 3.46 GHz, the filter features total power consumption of 1.4 mW, low noise figure of 5 dB, and IIP3 of −10.29 dBm.

LOW VOLTAGE CURRENT CONVEYOR-BASED FIELD PROGRAMMABLE ANALOG ARRAY

2011 ◽  
Vol 20 (08) ◽  
pp. 1677-1701 ◽  
Author(s):  
SOLIMAN A. MAHMOUD ◽  
EMAN A. SOLIMAN
Keyword(s):  
Low Voltage ◽  
Second Order ◽  
Current Conveyor ◽  
Total Power ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Programmable Analog ◽  
Total Power Consumption ◽  
Field Programmable ◽  
Field Programmable Analog Array

In this paper a low voltage low power field programmable analog array (FPAA) is realized. The FPAA configurable analog block (CAB) design is based on three-bit digitally controlled fully differential current conveyor. The FPAA consists of seven CABs. The CABs are directly connected together without adding extra hardware by placing them in a hexagonal lattice arrangement. A variable gain amplifier, tunable second-order low-pass filter, and a tunable second-order band-pass filter are realized as an application for the FPAA. The FPAA total power consumption is 105.12 mW at 1 V supply. The FPAA is realized using IBM 90 nm CMOS technology model from MOSIS under voltage supply of ±0.5 V.

Power Consumption Saving of Chiller Water System for Semiconductor Factory in Taiwan

2011 ◽  
Vol 314-316 ◽  
pp. 1492-1501
Author(s):  
Ching Liang Chen ◽  
Yung Chung Chang
Keyword(s):  
Power Consumption ◽  
Water Supply ◽  
Water Temperature ◽  
Cooling Tower ◽  
Reducing Power ◽  
Total Power ◽  
Water Cooling ◽  
Cooling Temperature ◽  
Total Power Consumption ◽  
Temperature Water

Recently, the semiconductor manufacturing industry has exhibited not only fast growth, but intense power consumption. Consequently, reducing power consumption is critical for running reliability. A view of literature reveals that the power consumption of facility system is 56.6 % in the fabs. Among all facility systems, chiller plants are the largest energy users, consuming 27.2 % of the total power consumption. Therefore, saving power consumption for chiller plants involves a considerable economic benefit. In addition, cooling the water temperature further improves the efficiency of chillers. Hence, this report analyzes the optimal temperature between the chiller and cooling tower. Currently, controlling the chiller and cooling tower are separate processes, though, in fact, they should not be. This is because the water cooling temperature affects the efficiency of the chiller. Each reduced degree of the chiller condenser temperature reduces the electrical power by approximately 2 % in the cooling tower, in contrast to the chiller. Therefore, the optimal water cooling water temperature must be analyzed. The analysis method in this report is linear regression. First, determine the equations of power consumption for the chiller and cooling tower with variables representing the water cooling temperature, water supply temperature of the chiller, and outdoor loading and wet-bulb temperatures. Second, add the coefficient of the same variable to obtain the total power consumption equation for the chiller and cooling tower. The result shows the relationships of power consumption with water cooling temperature under identical conditions of the water cooling temperature, water supply temperature of chiller, and outdoor loading and wet-bulb temperatures. Finally, use the differential method to determine the optimal water cooling temperature.

LOW-POWER, LOW-VOLTAGE, DUAL-OUTPUT, SECOND GENERATION CURRENT CONVEYOR AND ITS APPLICATION IN LOW-PASS FILTER DESIGN

2013 ◽  
Vol 22 (06) ◽  
pp. 1350044 ◽  
Author(s):  
MOHAMMAD HOSSEIN MAGHAMI ◽  
AMIR M. SODAGAR
Keyword(s):  
Second Generation ◽  
Current Conveyor ◽  
The Body ◽  
Total Power ◽  
Cmos Process ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Silicon Area ◽  
Total Power Consumption ◽  
Low Pass

A new simple dual-output second generation current conveyor (DO-CCII) circuit is proposed. Designed in a standard 0.5-μm CMOS process, the circuit operates at ±1.5 V supply voltages with a total power consumption of 106 nW. Main characteristics of the proposed DO-CCII are its simplicity, small silicon area consumption, and not suffering from the body effect of MOS transistors. The proposed circuit is employed to implement a first-order low-pass filter with upper -3 dB cut-off frequency of as low as 3.2 Hz.

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