Bina enerji yönetimi ve otomasyonun projelendirilmesi

Abstract

Tezde bina otomasyonu ve enerji yönetim sistemleri incelenmiştir. Bina otomasyonu konusuna ilk giriş algılama elemanları olan sensörlerin karakteristikleri ve seçim kriteleridir. Daha sonra bir otomatik kontrol sisteminin kararlı çalışmasını belirleyen oransal, integral ve türevsel parametrelerin ayarlanması anlatılmıştır. Diğer bölümlerde ise bina otomasyonu uygulamaları ve enerji yönetim sistemleri örnek simülasyonlarla birlikte verilmiştir.

Automatic control has played a vital role in engineering and science. Additionally, automatic control has become an integral part of modern manufacturing and industrial processes. For example, automatic control is essential in controlling pressure, temperature, humidity, viscosity and flow in the process industries. A system is a combination of components that act together and perform a certain objective. Sensors, actuators, controllers, disturbances are parts of a system. A sensor is defined as a device that receives and responds to a signal or stimulus. The purpose of a sensor is to respond to some kind of an input physical property ( stimulus ) and covert it into an electrical signal which is compatible with electronic circuits. A sensor is a translator of generally non-electrical value into an electrical value. Electrical signal information is modified by electronic devices. The sensor's output signal may be in a form of voltage, current or charge. All sensors may be passive or active. The passive sensors directly generate an electrical signal in response to an external signal in response to an external stimulus. The input stimulus energy is converted by the sensors into output energy without the need for an additional power source. Active sensors require external power source. Active sensors require external power for their operation, which is called an excitation signal. That signal is modified by the sensor to produce the output signal vu Sensors have some characteristics that represent the relationship between its output and input signals. Transfer function, span, full scale output, accuracy, calibration error, hysteresis, nonlinearity, saturation, repeatability, dead band, resolution, output impedance, excitation, dynamic characteristics to be taken care by the application engineer. Using an appropriate sensor for process accuracy is so important. Second chapter gives details about all kind of sensor characteristics. A sensor does not function by itself. It is always a part of larger system which may incorporate many other signal processors, memory devices, data recorders and actuators. A sensor is always a part of a system which includes various feedback loops. The simplest way to automate the control of process is through conventional feedback control as given in chapter 3. Sensors or measuring devices are installed to measure the actual values of the controlled variables. These actual values are then transmitted to feedback control hardware, and this hardware makes an automatic comparison between the set points ( desired values ) of the controlled variables and measured ( actual ) values of these same variables. Based on the difference ( error ) between the actual value and the desired values of the controlled variables, the feedback control hardware calculates signals that reflect the needed values of the controlled variables. These signals are then transmitted automatically to adjusting devices. The comparator, or error detector, is common to all feedback control systems. This is negative feedback control, i.e., the signal fed back to the comparator is subtracted from the set point. vin The various blocks of a feedback control loop have different types of dynamic behavior. Many of individual components of the process control loop have no time - dependent behavior, i.e., there is no lag in their operation when the input to the component changes, for all practical purposes, the output changes instantaneously. The output changes instantaneously when the input changes. In effect, the output is always proportional to the input and this proportionality constant will be referred to as the sensitivity or gain. Many individual components illustrate dynamic characteristics. Typically, their output will lag behind any input. The specific mathematical form of these dynamic lag is a differential equation with time. Process dynamic vary significantly from one individual loop to another, and the engineer must gain some appreciation and insight into the dynamics of an individual loop in order to design, install and tune the loop to provide quality control. Process control is obviously needed only in situations that are changing, i.e., if nothing is changing, control is not needed. Things that are changing are doing so with respect to time, and understanding their dynamic behavior is important. As a result, to understand process control, one must appreciate and understand process dynamic behavior. A controller can be made to operate a final control element, e.g., a valve or damper, in a number of different ways in response to a signal. The term " Control Mode " means the manner in which a controller moves the final control element ( actuator ) in response to a change in detector signal. IX There are five different modes or combinations ; ON / OFF INTEGRAL PROPORTIONAL PROPORTIONAL + INTEGRAL PROPORTIONAL + INTEGRAL + DERIVATIVE Most common continuous control mode is proportional control in which the controller is algebraically proportional to the error signal. This means that in integral action, the value of manipulated variable is changed at a rate proportional to the error. Integral control action usually is combined with proportional control action. The combination is termed proportional + integral action. This is referred PI control. Derivative control action is based on rate of change of the error signal. It is not theoretically possible to use an independent control action. Because the error might be huge, if it were unchanging, the controller output would be zero. Thus derivative control is usually found in combination with proportional. Control loop tuning can be achieved can be achieved by using the stability limit method or the step method. Energy in the form of electricity, oil and gas is used to light, heat and cool the environment space inside a building. The efficient use of these fuels results in significant savings whilst retaining the all important comfort conditions within the building. In addition to this a reduction in the use of any fossil fuel will considerably improve the environment outside the building. The BMS also provides a means of control. It is able to switch lighting on and off; to start and stop fans and pumps and to start and stop boilers and refrigeration machines. xni Energy in the form of electricity, oil and gas is used to light, heat and cool the environment space inside a building. The efficient use of these fuels results in significant savings whilst retaining the all important comfort conditions within the building. In addition to this a reduction in the use of any fossil fuel will considerably improve the environment outside the building. The BMS also provides a means of control. It is able to switch lighting on and off; to start and stop fans and pumps and to start and stop boilers and refrigeration machines. xni Nowadays, Building automation systems have a huge market to monitor and control other building services such as energy, security and fire protection systems. Other manufacturers also offer such systems, particularly in the fire and security sector and there is a rapidly increasing number of large and small firms with basic processor and software capabilities who are entering the market. It is advisable to question the level and validity of the software offered to perform the tasks required in the context of building services automation. Much of the software has still not been proven in practice and it is unwise to accept these programs until they have been demonstrated on a real project. One other area which requires emphasis is the possible susceptibility of all processor based systems to electrical interface. The rapid advance of microelectronics and the consequential reduction in equipment costs has made the consideration and use of these systems much more widespread. Because the technology and associated software are both still being developed this section covers the essential principles and requirements to obtain satisfactory systems. It also covers the facilities available and associated arrangements which are now being incorporated. The principles apply whether the system has one unit with 10-20 points or multiple processors and outstations serving 10000 points. The use of the term building automation system (BAS) is a generic title for all forms of data centers used in building systems data collection and control services. An energy management system (EMS) is one element of the BAS and some forms of BAS operate wholly as an EMS. Building automation systems use standard controllers and a standout computer which are linked together with a two core pair cable to allow communication to take place between the computer and the controllers. Each controller is fitted with a serial link port which allow the computer to talk through network cable or via a modem over the Public Telephone Line System.