COMBINED HEAT AND POWER ON BUILDING

Combined Heat and Power on Building

Abstract

This paper presents a novel design procedure for optimizing power distribution strategy in combined heat and power system. The optimal control problem was formulated as a nonlinear optimization problem subject to set of constraints. The resulting problem was solved using the Kuhn-Tucker method. Computer simulation results demonstrated that the proposed method provided better efficient in terms of reducing total costs compared to the existing methods. In addition, the proposed optimal load distribution strategy can be easily implemented in real-time thanks to the simplicity of the closed-form solutions.

Table of Content

Introduction4

Literature Review5

Combined Heat and Power5

Limitations of CHP14

Domestic Heat Demand15

Non-domestic heat demand16

Taking Advantage18

Heating and Cooling19

Strategies and Housing Types21

Passive Strategies24

Methodology26

System Configuration26

Control Strategy26

Optimization of Load Distribution27

Problem Formulation27

Cost Function28

Equality Constraints28

Optimal Method28

Results29

Analysis of the performance curve31

Combined performance curves32

References36

Combined Heat and Power on Building

Introduction

Advanced Distributed Generation (DG) system, compared to conventional centralized power plants, have potential benefits in increasing the electricity production, reducing emissions of air pollutants, and saving in energy expenditures due mainly to their improved efficiency of the Combined Heat and Power (CHP) as well as the quality and flexibility of the power delivery (Day, 2006, 3). On the other hand, the DG system has to be designed and operated as an integrated mode with multiple CHP units. In particular, coordination control of energy and distribution of torque (power) are essential elements in the implementation of DG system, where each power source must be used in according the total load demand and specific configuration. In fact, there might be an optimal power distribution to exist which would minimize a cost function or maximize system efficiency, so that the total operation cost of the system could be reduced. From this view, a set of studies focused on mathematical optimization approaches.

Figure 1

The DP algorithm is based on find an optimal solution at each searching phase, so that at the end the phase, the cost is minimum among all of the possible solutions. An alternative approach is to convert the optimal problem into a Sequential Quadratic Programming (SQP) problem via second order approximation of the cost function and constraints. Nevertheless, both DP and SQP provide the optimal numerical solutions (power distribution) to achieve the optimal design objective; however, they can not easily be implemented immediately in real-time due to their nature and heavy computational requirement. In this study, the optimal control design was formulated as a nonlinear optimization problem subject to set of constraints (King, 2007, 99-102.

The Kuhn-Tucker (KT) algorithm was employed to solve the optimal control problem based on minimizing operation cost of the system for the DG system. The KT method is more efficient than other methods such as DP and SQP. The simulation results demonstrated that proposed method provided better efficient in terms of reducing total operation costs compared to the existing methods. In addition, the proposed optimal load distribution strategy can be easily implemented in real-time thanks to the simplicity of the closed-form solutions.

Figure 2

Literature Review

Combined Heat and Power

Combined heat and power (CHP) ...