16/06/2019
ENERGY SAVING MICROPROCESS0R CONTROLLED SYSTEM
General Description
The system’s main function is to save energy by controlling the ‘Main Power Users’ in a home. These users include the Geysers, Air Conditioning, Pool pump and any other high power users. It excludes the stove as that is regarded as an Essential User.
The controller consists of various Modules which will be explained below:
1. POWER SUPPLY
The Power Supply is a Non Isolated design, meaning it is connected directly to the AC Line without use of a transformer. At the input is an IEC compliant EMC filter which feeds the High Voltage power IC. It also includes a Lightning Protection Circuit at the input.
2. REAL TIME CLOCK
The real time clock (RTC) controls the timing for all the different circuits cycle times and/or on/off times. The clock time is set during installation. The clock has a Battery Backup in case of power failure.
3. CURRENT TRANSFORMER
The Current Transformer is used to monitor the total Load Current of the house. This current is converted to an analogue signal value that the Microprocessor can use for calculations.
4. POWER SWITCHES
Each of the ‘High Users’ have a power switch wired into its circuit to enable the controller to automatically switch the ‘User’ on or off. This will depend on the total load current measured by the Current Transformer.
5. MICROCONTROLLER
The Microcontroller controls all the various timing functions, Power Switches and other Inputs and Outputs.
6. SERIAL/ USB PORT
The system has a serial Port to allow it to be interfaced to another device that also has a serial Port. This can be a GSM Controller, Automatic Metering System etc.
7. IOT Internet of things
The communication module will allow the user to view the operation and the condition of the electrical. The Data is stored on local web server and transmitter to an offsite database.
Power can also be monitored at outlet level,
Access is via a smartphone with use of internet and web browser.
Data is stored and reports can be generated to suite the clients requirements.
What is Power Factor?
Simply put, Power Factor is a measure of an electrical systems efficiency.
The apparent or total electrical power (Kilo Volt Amperes or kVA) used in an electrical system by an industrial or commercial facility has two components:
•Productive Power (Kilowatts or kW) which produces work.
•Reactive Power (Kilo Volt Amperes Reactive or kVAR) which generates the magnetic fields required in inductive electrical equipment (AC motors, transformers, inductive furnaces, ovens, etc.)
Reactive Power (kVAR) produces no productive work. Because the inductive electrical equipment employing magnetic fields requires this Reactive Power, which produces no productive work, the Total Power (kVA) provided by the generating source (your utility) must always be greater than the Productive Power (kW).
The ratio of Productive Power (kW) to Total Power (kVA) is called the Power Factor (PF = kW / kVA). It is a measure of the systems electrical efficiency in an alternating current circuit and is represented as a % or a decimal.
The relationship between kVA, kW and kVAR is non-linear and is expressed:
kVA2 = kW2 + kVAR2
In almost all industrial facilities where Demand charges apply, utility companies charge a penalty for poor power factor. Poor power factor is most often corrected through the use to Power Factor Correction banks.
In electrical engineering, the power factor of an AC electrical power system is defined as the ratio of the real power flowing to the load to the apparent power in the circuit, and is a dimensionless number in the closed interval of −1 to 1. A power factor of less than one means that the voltage and current waveforms are not in phase, reducing the instantaneous product of the two waveforms (V × I). Real power is the capacity of the circuit for performing work in a particular time. Apparent power is the product of the current and voltage of the circuit. Due to energy stored in the load and returned to the source, or due to a non-linear load that distorts the wave shape of the current drawn from the source, the apparent power will be greater than the real power. A negative power factor occurs when the device (which is normally the load) generates power, which then flows back towards the source, which is normally considered the generator. In an electric power system, a load with a low power factor draws more current than a load with a high power factor for the same amount of useful power transferred. The higher currents increase the energy lost in the distribution system, and require larger wires and other equipment. Because of the costs of larger equipment and wasted energy, electrical utilities will usually charge a higher cost to industrial or commercial customers where there is a low power factor.
Linear loads with low power factor (such as induction motors) can be corrected with a passive network of capacitors or inductors. Non-linear loads, such as rectifiers, distort the current drawn from the system. In such cases, active or passive power factor correction may be used to counteract the distortion and raise the power factor. The devices for correction of the power factor may be at a central substation, spread out over a distribution system, or built into power-consuming equipment.
Power factors below 1.0 require a utility to generate more than the minimum volt-amperes necessary to supply the real power (watts). This increases generation and transmission costs. For example, if the load power factor were as low as 0.7, the apparent power would be 1.4 times the real power used by the load. Line current in the circuit would also be 1.4 times the current required at 1.0 power factor, so the losses in the circuit would be doubled (since they are proportional to the square of the current). Alternatively all components of the system such as generators, conductors, transformers, and switchgear would be increased in size (and cost) to carry the extra current.
Utilities typically charge additional costs to commercial customers who have a power factor below some limit, which is typically 0.9 to 0.95. Engineers are often interested in the power factor of a load as one of the factors that affect the efficiency of power transmission. With the rising cost of energy and concerns over the efficient delivery of power, active PFC has become more common in consumer electronics
Phase control
In general terms, the energy saving device varies light level (intensity) of lamps by controlling the amount of power that is delivered to the lamp. Saving can be controlled by either manual or automatic means. There are two methods of saving: reducing the voltage applied (i.e., voltage modulation), as shown in Fig. 1, to the lamp and reducing the amount of time that full voltage is applied to the lamp (i.e., phase control). The applicable dimming method must be compatible with the lamp type. This article will focus on phase control.
CFL lamp, LED lighting and Halogen lamps respond well to our proprietary technology. Although incandescent lamps are still used in most countries and form part of an old requirement Incandescent still have a purpose in some lighting designs, they tend to consume the most energy and return the lowest efficacy (i.e., lumens per watt). The use of our saver with incandescent lamps can reduce their energy consumption and increase lamp life. Because incandescent lamps use resistive filaments, they can be dimmed by electronic technology with little to no problems. The use of LED and CFL provide the most saving and efficiency if the electrical installation is designed correctly. The lighting technologies can be supplied by SMPS (Switch mode power supply) enabling saving due to input voltage correction. The design includes energy standards as defined in Europe, USA and South Africa. The use of ROHS lead free components will be applied.
FUNCTIONAL DESCRIPTION
The ‘Main Power Users’ are firstly allocated a priority in the Controller Firmware.
The system functions by comparing the current household ‘Electrical Load’ against a user set ‘Maximum Allowable Load’. As long as the household Electrical Load is below the user set ‘Maximum Allowable Load’ the ‘Main Power Users’ can be used. As soon as the ‘Maximum Allowable Load’ is exceeded the Controller will start to disconnect the ‘Main Power Users’ until the current household ‘Electrical Load’ is equal or less than the user set ‘Maximum Allowable Load’. The controller does this by switching off the lowest priority ‘Main Power user’ first. If that does not reduce the load below the ‘Maximum Allowable Load’ then the Controller will switch off the next highest priority ‘Main Power User’ until the current household ‘Electrical Load’ is equal to or below the user set ‘maximum Allowable Load’. The Controller further controls the geysers and pool pump so as to ensure that these never run during peak load periods. In the case of the geysers the cycles ensure that there will always be hot water in the morning as well as in the afternoon. These cycles are controlled by the Real Time Clock.
GENERAL
It is estimated that up to 40% Electricity can be saved for a normal 3 bedroom house with 5 occupants (2 Adults and 3 Children) A further benefit is that the system will reduce the Peak Load Demand on the Grid during the 17h00 – 21h00 peak periods as no geyser or pool pump will be allowed to run during this period.
All remote switches to the Geyser, Pool Pump etc. are wireless thereby eliminating the need for cabling these. All that is needed for the switches is a 220V AC supply.
This document is copyrighted© 2008, 2009, 2010, 2011, 2012, 2013, 2014 2015 2016 2017 2018 2019 by the author and may not be copied or reproduced without the authors written permission For further information contact Dave Wailer 0726464951
