IntroductionThis report aims explore the workings of electricity supply systems how they are managed and the individual sections of the electrical supply grid.this report will also contain information about different types of electrical energy generation and how they operate along with a  section at the end which investigates power quality in regards to harmonic interferance and the measures that can be taken in order to minimise afforementioned interferance with the electrical system.Section 1-Electricity supply system (1a) (1b) Generators- produce electrical energy to be distributed throughout the supply network and are effectivly a machine which can generate electrical energy from mechanical energy this mechanical energy is usually generated from large wind/water turbines or heat.Overhead/underground cables- used to physically transport the electrical energy from place to place, these cables can range from typical power lines often located in isolated urban/rural areas to very large subtereanean cables that can transport vast amoubnts of energy underwater.local embedded generation- electricity station that is connected to a distribution network rather than a transmission network. (also refered to as distributed generation) transformers- used to alter voltage values dependant on what is required for example the amount of voltage required domestically will be far lesser than the power requirements of heavy industry.Bus bar – A Busbar is a metallic strip or bar (typically copper, brass or aluminium) that conducts electricity within a switchboard, distribution board, substation, battery bank, or other electrical apparatus. Its main purpose is to conduct a substantial current of electricitySubstation- The substation is used in order to convert high voltage from the distribution system into a lower voltage for further transmission or for consumer usage.Transmission system- allows power to be effectivly distributed thorughout the national grid.Distribution system- allows power to be delivered to the energy consumer via the transmission system.This system of power distribution is designed so that if one sector of the network fails or requires maintenence electricity can still flow due to the fact that an alternate route for the electricity to travel will always be available.(1c) EC Standard 60364 uses Two Letter Codes to identify types of earthing. And there are three main families of these earthing systems, The three families are as follows and are also recognized IEC standards: TN Network-In this type of earthing system one of the points of the Generator is connected to earth. This point is generaly the star point in a three phase system.IT network –  With this type of earthing system there is either no connection to earth at all or it is done via a high impendence earthing connection.TT network- This type of earthing system utilises its own local earth connection in the installation which is independent of any earth connection at source side. This type of earthing is preferred in telecommunication applications.(1d) Section 2-Energy Sources2aFossil FuelsA fossil fuel power station burns fuel such as coal gas or petroleum to produce electrical energy. This method of energy production is still very popular across the globe but is being phased out due to its effects on the environment as fossil fuels have a very high carbon footprint and contribute to the greenhouse gas effect. The output energy from these plants varies dependant on size, For example the Amravati Thermal Power Station in india has a capacity of 2700 mW.NuclearA nuclear power plant uses nuclear reactors to generate large amounts of heat energy, heat is used to generate steam which drives a steam turbine connected to a generator which produces electrical energy. Nuclear energy is very efficient and produces a very large amount of energy for a relativley low cost, however the big problem lies in what to do with the nuclear waste that is produced as it is highly hazardous to both animal and plant life alike, This waste is usually encased in thick barrells and buried very deep into the ground, this is necassery considering that radioactive substances usually take over 100,000 years to become no longer hazardous. The amount of electrical energy that a power plant generates over a period of time depends on the amount of time it operates at a specific capacity for example 21% of the united kingdoms energy comes from nuclear power stations. France is the country that relies on this form of energy the most with over 70% of there electrtical energy being produced using this method. This method of energy generation is the most efficient of the non-renewables as nuclear fuel rods last a very long timeWindWind power is quickly becoming one of the most popular methods of renewable energy generation due to its low cost and abundance. Wind turbines can be installed both on and off shore and effectivly use the power of the wind to turn turbione blades which in turn drives the turbines generators thus providing electrical energy. An average onshore wind turbine with a capacity of 2.5–3 MW can produce more than 6 million kWh annualy. Hydro-electricHydro power is acheived usually by the construction of dams so that the water can then be used to turn turbines in the dam thus producing electricity. Like wind power hyrdo electric power plants are a very clean  and cost effective source of energy. Hydro electric plants are very efficient and can produce up to as much as 90% of the available energy into electricity unlike coal in which the efficieny rating is around 50%. China is currently the world leader in overall hydro generated power and is host to the worlds largest electricity producing dam ” the three gorges” which provides 22,500 megawatts per annum.2bLoad balancing is efrfectivly an issue of how to store energy for when it is not peak time and demand is low. This can be done by storing the energy in the transmission grid or by extending the involvement to the consumer end, for example in the UK many home heating units run a demand-response tarriff which offers subsidised energy at non peak times.2cMaximum demand- The highest level of demand monitored over a certain period of time ( usually 1 month). if all the peak loads were to be added this would be equal to the maximum demand. The ratings for certain power systems usually prove to be troublesome as demand has a rather large scope of variation.load factor- The load factor is defined as the average load divided by the peak load in a specified time period or in lehmans terms load factor is a measure of how steady the demand is over a given period of time.diversity factor – The percent of time available that a machine piece of equipment is operating at its full capacity (example if a sytems diversity factor in 60% then the system is running at full capacity 60% of the time)The diversity factor is mathematically described as (Diversity factor= sum of max demand/maximum demand on power.)both load and diversity are utilised by energy and utility companies in order to calculate the sizes required for distribution transformers.2dmonitoring energy is very important for a plethora of reasons with one being economics, this means that energy is monitored in order to ensure that the system is operating at its best and is producing the most amount of energy that it can without compromising anything financially.Another reason for monitoring energy is for general safety and fault prevention as if there was a major fault at certain points in the system the results could prove to be highly dangerous to both the equipment and people. Section 3-Power Quality3aHarmonics are a way of describing distortion to a voltage or current waveform. rates of harmonic related problems are low but awareness of harmonic issues can help to increase plant reliability.Power system problems related to harmonics are rare but it is possible for number of undesirable effects to happen. High levels of harmonic distortion can cause such effects as increased transformer capacitor motor or generator heating misoperation of electronic equipment ,incorrect readings on meters, misoperation of protective relays or interference with telephone circuits.3bThe harmonic filter is built using an array of capacitors, inductors, and resistors that deflect harmonic currents to the ground. Three-phase harmonic filters are used in power systems for decreasing voltage disruption and for correcting power levels. Typical apllications of thes harmonic filters include Installations where current distortion must be reduced to avoid overloads and Installations where voltage distortion must be reduced to avoid disturbing sensitive loads.