Distributed Power System Network with Renewable Sources - Coursework Example

Distributed Power System Network with Renewable Sources s Submitted by s: Distributed Power System Network with Renewable Sources Objectives of the study • To understand how to simulate a power system network with multiple renewable energy sources. • To understand the effect of distributed network on relay coordination and filter design. SIMULATION AND APPLICATION OF DC ENERGY IN DISTRIBUTION SYSTEM FOR HYBRID RENEWABLE ENERGY SYSTEMS ABSTRACT Distributed Power System Network with Renewable Sources is the situation where renewable energy sources like solar, hydrogen, and wind are used at the same time. In the past years, the increase in the petroleum prices, coupled with tendency of fossil fuel reserves and their dangerous effects that cannot be avoided and the lack of political stability in the sources of energy regions have led to the renewable energy systems study (Air-X, 2008). In this case, electrical energy is outputted by the systems of renewable energy systems like fuel cells and photovoltaic panels in direct current form. As a result, regardless of the fact that the electrical energy produced by the wind turbines is directly proportional to the wind velocity making it alternative current (AC) , undergoes conversion back to dc energy by the converters found internally in the small-scale turbines of the wind that are utilized in structures like buildings (Cete, 2010). This network is then injected with Direct Current energy. Thus, the DC energy outputted through the wind turbines, fuel cells and photovoltaic panels. The DC energy produced cannot be used readily by the consumers without having been converted to AC energy. This is given the fact that the consumer uses electricity in AC form. The conversion from DC to AC has a few challenges like the improvising of DC to AC converter. There are also disadvantages related to this conversion are; energy loss, partial energy degradation, harmonics production, cost and dimension increase (Siemens, 2009). Electrical energy transmission from the place of produce to the consumer, pose the predicament of losing energy. To avoid this predicament, we need to avoid the use of the DC to AC conversion to produce the AC energy. Thus in this study, a Mat lab© simulation software will be made for hybrid system of Direct Current system and thereafter, it will be applied, in the process of production of DC energy through RHESs and in this manner the DC loads like freezer or refrigerator, 44 compact florescent lamps, fans, TV circulation pump, and vacuum cleaner consume the DC energy in a way that it is not converted into the form of AC (Colorado, 2010). This is will be presented in this paper project as we get to discuss the simulation of the renewable energy. It is for this reason that the unit distribution of the DC energy ought to be established for the fuelling of the hybrid energy cell system of photovoltaic wind. INTRODUCTION It is indisputable; technologies in the energy have a main function in the development based on the economic and small scale level, which varies from domestic, society to region, nation and international. Conventional fossil fuel sources like coal, oil, natural gas are becoming rare as the time goes by. Additionally, by the using the sources of fossil fuel, it is predictable that they pollute the nature in the end process, resulting to the global warming through the formation of the greenhouse outcome thus the world is turned into a night mare that is not desirable for anyone to live in. Thus, sources of renewable and alternative energy got significance that has greater priority over the history of the mankind. (Air-X, 2008). There has been an increase in the study of renewable and the new kinds of energy due to the current sources of energy output that make a quick entry into the tendency of exhaustation that the raw material prices rise significantly, as their effects affect the human health and environment in a negative way. The some challenges faced in the use of these kinds have increased the studies made on the sources of new and renewable energy sources (Cete, 2010). The incorporation of the renewable energy into the grid of utility can be at the level of transmission or distribution, being dependant on the generation scale. In case of large generation of the renewable energy are interconnected directly to the system of transmission. On the other hand, generation of small scale distribution is usually connected to the other distribution systems of low or medium voltage (Colorado, 2010). In these 2 types of interconnections, there are various difficulties that need keen analysis prior to the design of the distribution systems. This paper will thus discuss as it outlines the mainly widespread issues that are faced in the integration of grid in various renewable systems of energy. In this way, the paper will obtain the simulation methods in detail to trace the problems and the most suitable solutions to these problems. It is in this respect, the paper will give good simulation examples to put more emphasis on this matter (Cete, 2010). Electrical energy distribution from the location of generation to another the location of consumption encounters many loses in the process of power generation. In systems of power distribution, the technology of Alternative-Current (AC) in the distribution generally is put into practice. Electrical energy distribution from the Hybrid Renewable Energy Systems (HRES) with very low losses is crucial essential as these systems have the intermittent production nature and are expensive. Power factor are dominant in the distribution of AC energy and has a negative effects on the distributed active power. In distribution of DC energy, there is no loss in the energy as the case in the above scenario. This is due to the reason that the value of the power factor is unity (1). Using the same conductor as was used in the Alternating Current scenario, it is observable that Direct Current voltage usually supplies more power than the counterpart, voltage of the Alternating Current. Control of voltage in distribution of the Alternating Current has a few difficulties in case of the capacity of the line and drop in the voltage induced consideration (Siemens, 2009). In AC energy distribution, there are some problems which exist in DC energy distribution less than the distribution of AC energy like active losses, voltage oscillation, current limitations carriage capacity, problems of stability, drops in the voltage, interactions in line, effects of frequency, voltage drops, expenses in power plant power plant expenses etc. Today, even though the Alternating Current energy has these challenges, it is broadly utilized as power stations such as natural gas, hydroelectric which are conventional have available appropriate Alternating Current devices and alternators for utilization. Despite this, the energy generated through system of fuel cell, photovoltaic, and turbines of wind (which have DC to DC converter inside of them) is Direct Current, and also in the instance of use of DC loads, DC to AC conversion is not necessary. Thus the problem posed in above scenario is eliminated (Cetin et al., 2010a). 2. Small scale generation integration into the grids of distribution The generators of small scale are interconnected at the secondary and the primary level of distribution and are therefore DG (Distributed Generation) or rather DR (Distributed Resources). These are inclusive of now-renewable and renewable generation in the small scale as is the storage of energy. 2.1 Various types of grid interfaces In most cases, the low scale generators are indirectly connected to the grid. The characteristics of operation and the technology of generation need the incorporation of some interfaces in between the grid of distribution and the generator. For instance, photovoltaic panel of solar produce direct current electricity and thus, converter based on the power electronics is needed in between the generator and the grid. In technologies like induction generator using wind or hydro, this generator is directly connected to the Alternating Current grid. 2.2 Protection issues In the interconnection of the distributed generation, protection is essential. Distribution network is configured in the radial form. In this radial form, the network has over current schemes of time graded protection. The connection of the Distribution Grid may change the present schemes of protection coordination. In case, this is ignored, the protection system may fail to work. The major issues with relation to the Distribution Grid interconnection are as follows: (a) Short circuit change levels This is the major measure useful in coordinating between over current relays and the selection of current transformers, fuses, reclosers, circuit breaker. The characteristic of short circuit is the equivalence system impendence at the points of and in this way, shows the fault current level that is expected. The variation in the time of this faulty current is affected by the rotating machinery characteristics (Cete, 2010). The majority of Distribution Systems are at first made without the Distribution Grid. Contrary, having connected the Distribution Grid, the network impendence equivalence can reduce, leading to rise in the level of fault. Therefore, in presence of fault, fault currents can be quite high. This might be exceeding the existing circuit breakers interrupting capacity. These elevated levels of the fault currents may lead to the saturation of the CT. In the same way, the fault levels change levels might interrupt the coordinating between the relays of high current resulting to lack of satisfactory function of the protection systems. (b) Reverse flow in power In the case of radial distribution systems, the flow in power is in one direction. In this system, the schemes of protection are at first on the basis of the flow in power. As soon as the Distribution Grid is linked, the flow in power might be reversed (Cete, 2010). This may even change the protection relays coordination. (c) No sustained faulty current For the protection relays conveniently sense and single out the currents that are faulty from the ones that are normal as load currents, the faults ought to create a great and constant rise in the currents measured by the relays. In this scenario, if the contribution of fault from Distribution Grid is restricted, it is hard for the high current relays to detect faults effectively. The shortage of the constant fault current incorporates the relays ability to sense faults (Siemens, 2009). (c) Islanding This is the instance where the utility network part is cut from the main part of the grid and functions as its own co independent system with one or more generators supply. The results in variations of abnormality voltage and frequency show an isolation called (island). Island is not a safe condition and so the Distribution Grid should be disconnected immediately with the island formation (IEEE, 2003). 3.0 The System Network Simulator The power system network simulator has a solar panels, micro wind turbine and generator set as the prime mover (Colorado, 2010). The PLC in this power system network simulator controls the operations of AVR, Governor and the synchronization. The bus bar and generation relays are used for the module generation. In summary from the circuit below we can classify the modules parts of simulation as follows: Generation module for the generation purposes Substation module as the interface between generation and transmission Transmission line module for the transmission of the AC electricity Distribution Network Module for the distribution electricity to the consumer as the end From the circuit the above category can be put in table form as below the circuit on table where each module part has components with specific features. (Cete, 2010) This clearly shows how the simulation of the power network takes place. The circuit diagram of distributed power system network with renewable sources The table that follows illustrates the simulation of the individual module part with the associated features or characteristics of the components in each module. Model of generation Module of generation could consists of Features Generator motor set of 1.2 kVA, 220V, 50Hz of Single Phase Active power with a frequency control Sources of renewable energy sources such as 200W wind turbine, Inverters, 200AH battery , 200W solar PV A reactive Voltage/power control Synchronizing relay which is relay 1 on the circuit diagram Synchronization that is manual and auto Generator Control Panel Automatic Load Frequency Control(ALFC), Shearing of the load, Area Control Error(ACE) Generator Protection relay-Reverse Power, Over current, Under voltage. This is possible through relay 6, 8, 11, 13 and 16 as illustrated on the circuit diagram. Protection of the relay coordination Module of Substation The Module of the substation has the following; Characteristics Step down transformer( ie T2, T3, T5, T4 and T7 for stepping the power from grid from 1.2 MVAc to10MVA For the regulation of the voltage One and Half Breaker, Double Bus Bar 4, 6, 8, 9 and 10 For the compenstion of the shunt Contractor relay operated Circuit Breaker. These relays from the circuit are relay 7,9, 12, 14 and 17. Loading of the transformer Protection Relays of under voltage and over current. These are relay 10, 15 and 9. Operation of the Local and remote Ammeters and Voltimeters For interfacing the Matlab Simulink Transmission Module This consists of Features Single phase, Resistor,Inductor, Scaled down model of transmission, Capacitor in Pi connection configuration Calculation of the transmission line loss Compensation of shunt Effect of ferrient Compensation of series Compensation of Series and shunt Relays of protection from under voltage and over current Simulation of the fault Multi funcion Meters Matlab Simulink Interface Circuit Breakers of are operated by the contactor relays in their functions, PT,CT Opening and closing line Module of distribution The distribution module network has the following; Feature Transformer of distribution of 1kVA Auto transformer System of Distribution Management Banks of capacitor Shedding of the load Loads of the following; Single Phase Motor of 0.5 HP,230V,50Hz, Lamp Loads of 1kW Coordination of relay Relays of protection from under voltage and over current Studies of motor starting Multi funcion Meters Matlab Simulink interface Circuit Breakers of are operated by the contactor relays in their functions, PT,CT Improvement studies on the power factor Conclusion In conclusion, have observed that in the simulation process some energy sources like wind are omitted first in the process (Siemens, 2009). In the study we have identified different challenges and issues that require solutions. These solutions are applicable in the integration of grid of the energy that is renewable. The main focus in interconnecting of small-scale generation of this renewable energy at the level of distribution are protection related, power and voltage quality. The main issues cosidered in the big wind farms interconnecting of the grid are;requirements of the reserve and reactive power as well as the support of the grid in the disturbance time. We have seen that the significance of the tools of simulation is that in itegration of the studies in grid can be shown via a few study cases. References Air-x Owner’s Manuel PDF Version, 2008. Online< http://www.windenergy.com> [Accessed on 15th December 15, 2013] Cetin, E., 2010. Design, application and analysis of a direct-current distribution grid for a photovoltaic-wind-fuel cell hybrid energy system. Ph. D. Thesis, Ege University Solar Energy Institute. 183 p. Cetin, E., Yilanci, A., Ozturk, H. K., Hekim, M., Kasikci, I., Colak, M., and Icli, S., 2010a. ‘Investigation of DC and AC power distribution systems for renewable energy applications’ 5th International Ege Energy Symposium & Exhibition, June 27-30, Denizli-TR. Cetin, E., Yilanci, A., Ozturk, H. K., Colak, M., Kasikci, I., and Iplikci, S., 2010b. A micro DC power distribution system for a residential application energized by photovoltaic-wind/fuel cell hybrid energy systems. Energy&Buildings. 42 (8). 1344-1352. Colorado, 2010. Online< http://ecee.colorado.edu/~ecen2060/matlab.html> [accesed on15th December 15, 2013] Siemens Product Catalog, PDF version, 2009. Read More