The Issues Related to Maintaining Power Quality in Electrical - Assignment Example

Name Tutor Course Date Power Quality Components of Power Quality The question is whether the electrical supply is able to efficiently support proper operation and longevity of the electrical devices and ensure that uninterrupted operation. It has been established though that frequency and current will have little effect on the performance of the electrical system and will are not the cause of problem for the consumers. This is true because current is dictated by the load while the utility almost completely controls the frequency in the case for AC power in order to maintain grid stability. The quality of the power will therefore depend on voltage quality. Statistics have indicated that more than 95% of the power quality problems are in fact associated with voltage. They include too low or too high voltage levels, sags in voltage (which are voltage transient drops) and power interruptions (voltage absence). Voltage quality will affect the operational reliability of sensitive electronic equipment as well as their life. It will also significantly impact on energy efficiency and consumption. The voltage disturbances, obviously, results to disturbances of current and even power frequency so that efforts directed to achieving power quality must ensure that all these are satisfactorily stabilized (Utilities Systems Technologies, Inc., 1). Quality power therefore would be one that is closest to the ideal situation of constant magnitude with sinusoidal frequency voltage waveform. The loads connected to this power will therefore run satisfactorily and efficiently with minimal installation running costs as well as carbon footprint (Schipman and Delince 1). Importance of high quality power Electrical engineers have continued to pay much attention to the quality of power that they supply for different users. The need for high quality power has been on the rise both in industry as well as domestic consumers and efforts have been directed to minimizing effects of poor power quality that include unexpected supply failures, overheating of equipment, more system losses, and communication interference. Industrial processes now depend on very sensitive electronic equipment. These equipment like drives, sensors, computers and motion controllers which are at the heart of quality, optimal productivity and consistency, require stable and clean electrical quality in order to perform properly. Power disruptions and distortions, power outages, voltage fluctuations, harmonic distortions and noise will certainly result to disruption of production, data loss or corruption of valuable information or damage to electrical equipment (Newark, 2013). This damage may spread even to the entire building in from of electrical fault fire and in this way lead to loss of property and even life. Low quality power is also associated with higher costs of transmission and distribution. Poor power factor is a major cause for high operating costs. Electrical transmission and distribution systems ensure enhanced power quality through power factor improvement and in this way save cost and also ensure quick return on the investments (Siemens, 2010). These effects of unregulated low quality power cannot be tolerated in this competitive environment hence the need to maintain high quality power at all times. Factors Impacting Power Quality The power flow in power systems experiences several disturbances that contribute to poor quality power. Major disturbances include surges, sags, transients, harmonics and power interruptions. Although most disturbances will originate externally without prior warning, some are in fact generated within the consumer’s facility. Turning on or off huge electrical equipment may cause electrical surges in the system. Other causes of disturbances include wiring errors, grounding loops, improperly serviced power conversion equipment, or even normal daily operations. These factors promote power quality issues leading to disturbances (Newark, 2013). Extreme weather conditions like storms are another cause of external disturbances to the power system. Lightening may cause power surges in the system which may be disastrous. Other external causes include power line accidents and utility fault clearing and other issues like power factor correction capacitors or grid switching. These disturbances are associated with spikes, surges and power interruptions that could easily damage equipment. A great challenge with these external sources of disturbance is the fact that they are totally unpredictable and may occur when least expected. Electricity cannot be stored for use some other time, it must be produced when demand arise. Generation facilities must therefore be able to accommodate the demand and proper forecasting is important. But as the demand rises so that supply and demand gap falls below 10%, consumers begin to experience increased interruptions and local brownouts. This may turn out to be a major contribution to poor quality power until generation capacity is sufficiently expanded (Utilities Systems Technologies, Inc., 2) Poor power quality may still be contributed to by reactive power which creates unnecessary increase in load to the system. Harmonic pollution is another factor. This causes additional stress on the powers system making installations run inefficiently. The systems also experience load imbalances mostly in office building applications. Such unbalanced loads results in excessive voltage imbalance that stresses other loads that are connected to the network and consequentially increasing the neutral current as well as neutral to earth voltage build up. All these potentially contribute to inefficiencies in running of installations, reduced equipment life and system down time and ultimately high installation running costs (Schipman and Delincé 2). Controlling and Improving Power Quality The control and improvement of power quality is achieved through different ways. Efficient power system requires proper planning and forecasting of demand during designing of power generation facilities so that the system is not overloaded, but is able to comfortably handle the peak loads. Other control measures range from ensuring proper set up and wiring of appliances to the inclusion into the system of protection and control equipment that will function together to correct any disturbances that may arise during transmission and distribution of the power as well as those due to faults within the system. It is important to ensure integrity of the distribution system within the facility. This can be done by continuously inspecting the bonding system, grounding, and wiring (Albert 1). Although it has not been given much attention in the context of power quality, incorrectly configured grounding and bonding will most often result to poor system performance. Designers should be keen to ensure that neutral and ground are bonded together only at the service entrance. A common error is where the ground and neutral are bonded in multiple locations in the system. These extra bonding points must be identified and done away with (Albert 2). While these bonding points are sought, it must be ensured the whole system is checked to avoid loose, improper or missing connections at the panels, equipment and receptacles. Consumers may also install different power conditioning equipment to further minimize these disturbances. Important equipment would be the Transient Voltage Surge Suppressors that are one of the simplest ways to control power. The units clamp the transient impulses to such a level that they cannot damage other devices. A multi-stage protection will involve installing these devices at the entrances, sub-panel as well as the points of use. For a three phase drive, there is usually installed a Line Reactor and in some cases a Drive Isolating Transformer that is installed into the power supply. These equipments function to ensure a defined line impedance is achieved and in this way minimizing the level of SCR induced “notching” as well as total radiated electromagnetic RF noise on the supply. The choice of whether to use line reactor or isolation transformer depends on the industrial system’s consideration like whether or not there is need for isolation to further improve the system safety (Bardac drives, p1) Filters may also be used to protect the equipments against high-frequency low-voltage noises. They are designed to allow the fundamental frequency while rejecting any higher frequency voltages that may result from electromagnetic interference and radio frequency interference (Albert 3). A common way to control and minimize fluctuations of the power factor is the use of contactor switched capacitor banks. These power factor controllers will compare the reactive power in the network with a preset value and will switch on the capacitor steps to achieve the set target. When these units are put to use however, it must be ensured that the controller can properly operate even in the presence of harmonic pollution and it should have capacity to handle regenerative loads. In the case where the requirement for reactive power is not stable, but keeps fluctuating fast or is too high, it is desirable to employ Thyristor Switched Capacitor banks instead of the contactor switched capacitor banks. An example would be the reactive power demand of a large harbor crane which cannot be typically compensated by the contactor switched capacitor banks (Schipman and Delincé 6). Active filters are becoming increasingly preferred to the passive filters in LV and MV installations. An active filter usually consists of a control system and a power stage. The power stage employs a IGBT-based PWM inverter that is coupled to the network by a coupling circuit. The IGBT switches amplify and controls signals that represent compensated voltages and currents. Within the coupling circuit is an output filter section that acts as a low-pass filter which absorbs the high frequency switching components coming from the PWM inverter but leaves the compensating harmonic currents to flow. The control system on the other hand measures current to obtain information on the harmonics present in the network. It then calculates control signals that are finally sent to the PWM inverter where they are amplified then coupled to the supply network (Schipman and Delincé 13). Several other components exist, including voltage regulators, for correction of voltage sags, brownouts and swells, tap changers, buck boost, constant voltage transformers, uninterrupted power supplys, and so many other devices that collectively help achieve high power quality. Technological advancement continues to provide more options in the field of electrical engineering. Works Cited Albert S., 2006, Total Power Quality Solution Approach for Industrial Electrical Reliability, retrieved on 20th September 2013 from Schipman K. & Delincé F. ,2013, The importance of good power quality, retrieved on 20th September 2013 from Utilities Systems Technologies, Inc., 2009, 2010 Power Quality Forecast Are Improvements on the Horizon?, retrieved on 20th September 2013 from Bardac drives, 2013, Power quality components, retrieved on 29th September 2013 from Siemens, 2010, Power quality solution key components, retrieved on 29th September 2013 from Newark (2013). Power quality guide book, retrieved on 20th September 2013 from Read More

These equipment like drives, sensors, computers and motion controllers which are at the heart of quality, optimal productivity and consistency, require stable and clean electrical quality in order to perform properly. Power disruptions and distortions, power outages, voltage fluctuations, harmonic distortions and noise will certainly result to disruption of production, data loss or corruption of valuable information or damage to electrical equipment (Newark, 2013). This damage may spread even to the entire building in from of electrical fault fire and in this way lead to loss of property and even life.

Low quality power is also associated with higher costs of transmission and distribution. Poor power factor is a major cause for high operating costs. Electrical transmission and distribution systems ensure enhanced power quality through power factor improvement and in this way save cost and also ensure quick return on the investments (Siemens, 2010). These effects of unregulated low quality power cannot be tolerated in this competitive environment hence the need to maintain high quality power at all times.

Factors Impacting Power Quality The power flow in power systems experiences several disturbances that contribute to poor quality power. Major disturbances include surges, sags, transients, harmonics and power interruptions. Although most disturbances will originate externally without prior warning, some are in fact generated within the consumer’s facility. Turning on or off huge electrical equipment may cause electrical surges in the system. Other causes of disturbances include wiring errors, grounding loops, improperly serviced power conversion equipment, or even normal daily operations.

These factors promote power quality issues leading to disturbances (Newark, 2013). Extreme weather conditions like storms are another cause of external disturbances to the power system. Lightening may cause power surges in the system which may be disastrous. Other external causes include power line accidents and utility fault clearing and other issues like power factor correction capacitors or grid switching. These disturbances are associated with spikes, surges and power interruptions that could easily damage equipment.

A great challenge with these external sources of disturbance is the fact that they are totally unpredictable and may occur when least expected. Electricity cannot be stored for use some other time, it must be produced when demand arise. Generation facilities must therefore be able to accommodate the demand and proper forecasting is important. But as the demand rises so that supply and demand gap falls below 10%, consumers begin to experience increased interruptions and local brownouts. This may turn out to be a major contribution to poor quality power until generation capacity is sufficiently expanded (Utilities Systems Technologies, Inc., 2) Poor power quality may still be contributed to by reactive power which creates unnecessary increase in load to the system.

Harmonic pollution is another factor. This causes additional stress on the powers system making installations run inefficiently. The systems also experience load imbalances mostly in office building applications. Such unbalanced loads results in excessive voltage imbalance that stresses other loads that are connected to the network and consequentially increasing the neutral current as well as neutral to earth voltage build up. All these potentially contribute to inefficiencies in running of installations, reduced equipment life and system down time and ultimately high installation running costs (Schipman and Delincé 2).

Controlling and Improving Power Quality The control and improvement of power quality is achieved through different ways. Efficient power system requires proper planning and forecasting of demand during designing of power generation facilities so that the system is not overloaded, but is able to comfortably handle the peak loads. Other control measures range from ensuring proper set up and wiring of appliances to the inclusion into the system of protection and control equipment that will function together to correct any disturbances that may arise during transmission and distribution of the power as well as those due to faults within the system.

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