Micro- Grad Central Voltage Controller for Local Area Voltage Control

1.1 Increase demand of electricity

Arguably, having access to electrical energy in this contemporary world comes with a momentous effect on the human  life, in particular when they require an energy  source for heating, lighting, machinery generator, power, and many more. With no electricity, the public is faced with loads of setbacks in their day after day activities, and for enormous organizations electricity blackout denotes loss of millions of pounds because of not managing to hold up processes and other organizational activities (Davidson, 2005). Conversely, such activities guzzle an incredible amount of electrical energy annually. In essence, individuals need energy given that a range of fiscal activities rely on electricity and change in standard of living has compelled people to use more electrical machines like a vacuum cleaner, washing machine and computer, which in turn has led to increase in electricity demand. What’s more, income rise has led to increased demand of electricity given that they will make use of more electrical machines in particular refrigerators, air conditioners, and heaters which consume more electricity. Besides that, population rapid growth has arguably increased electricity demand periodically (Davidson, 2005).

1.2 Increase price of energy

The fundamental reason of the current price increase of energy has been due to escalating costs of electricity transmission and distribution. Fundamentally, these costs have been increasing due to improved investment in the distribution and transmission networks. According to Davidson (2005), the electricity networks owners are improving them to: substitute old infrastructure, inflate networks in order to handle with demand peaks for electrical energy, and meet elevated security and dependability standards. Moreover, the exhaustion of low-priced traditional “easy oil”, alongside lack of victuals and water ought about by population growth and climate change has elevated the prices of energy. Other causes of energy price increase include privatization of power and rising demand for fossil fuels (Dhawan & Jeske, 2008).


1.3 Increased carbon foot print

Presently, the word “carbon footprint” is frequently utilized as shorthand for the quantity of carbon being released by a company or certain activity. Suresh et al. (2010) posit that the Ecological Footprint carbon element pursues somewhat conflicting method, interpreting the quantity of carbon dioxide into the quantity of sea area and useful land needed to confiscate emissions of carbon dioxide, which exhibits the world demand stemming from burning fossil fuels. Essentially, the carbon Footprint is roughly 55% of people’s entire Ecological Footprint as well as its most hastily-increasing element. According to Suresh et al. (2010), the human race carbon footprint has augmented 11 times since 1961; thus, decreasing the human race carbon Footprint remains the most fundamental step the human kind can pursue to stop overshoot. What’s more, the Footprint structure allows the human race to deal with the setback expansively, one that does not just change the load from one natural system to the next.

1.4 Renewable energy

According to Manzano-Agugliaro et al. (2013), renewable energy is energy obtained from natural resources, which are incessantly, replenished like rain, waves, tides, and geothermal heat. What’s more, technologies of renewable energy comprise of technologies that employ or permit the application of one or several sources of renewable energy. Technologies of Renewable energy include; bioenergy, ocean energy, wind energy, hydropower, hybrid, geothermal energy, and solar energy. Moreover, technologies of renewable energies comprise those technologies that are allied to renewable energy. For instance technologies that: amass energy produced through renewable energy, help in the release of energy produced through renewable energy technologies to clients, and forecast renewable energy supply (Manzano-Agugliaro et al., 2013).

2.0 Literature survey

2.1.0 Micro-grids (in general)

Micro-grids are contemporary, modest editions of the centralized electrical energy system, whose aim is to attain precise local objectives, like consistency, energy sources diversification, carbon emission reduction, and expenditure diminution. Similar to the bulk power grid, micro-grids produce, allocate, and control the electricity flow to customers, but only close by (Yi-nan & Xiao-rong, 2011). Arguably, micro-grids provide a perfect method of combining renewable resources and permitting the customer to take part in the electricity project.

2.1.1 AC type of micro-grid

The AC type of micro-grid consists of wind power generation (WG) and photovoltaic (PV) systems, a bi-directional converter, interactive inverters, AC load and DC load, and storage batteries. Essentially, the DC power produced by WG and PV generation is transformed into AC power by an interactive inverter and distributed to the AC load. At the moment, if the load power demand is greater as compared to the quantity of WG and PV produced energy, a quantity equivalent to the power scarcity is distributed using the bi-directional converter from the storage batteries (Justo et al., 2013). What’s more, in case the load power demand is a smaller amount as compared to the quantity of PV produced energy, the excess energy is utilized for charging the storage batteries using the bi-directional converter.

2.1.2 DC type of micro-grid

The DC type of micro-grid comprises of WG and PV generations, a bi-directional converter, DC/DC converters, AC load and DC load, and storage batteries. According to Justo et al. (2013), the DC power generated by WG and PV generations are linked to the DC-bus by means of a DC/DC converter, as well as energy  is distributed using the bi-directional converter to the DC load and the AC load. At this moment in time, if the load power demand is generously proportioned as compared to the quantity of power distributed through WG and PV generations, a quantity equivalent to the power scarcity is distributed through the bidirectional converter from the storage batteries (Justo et al., 2013).

2.1.3 Centralized micro-grid

Centralized micro-grid is fundamentally a synchronization of two power modes-control by means of converters and converter entities choice. According to Yi-nan and Xiao-rong (2011), the power via the converter is regulated for the reason that the load unbalance amid DC and AC buses should be alleviated. In centralized micro-grid, converter unit’s choice is as well significant because all diminutive units can deal inequitable power quantities of the whole micro-grid system, and as a result, takes into account the parallel operation control of various converter units. What’s more, in case one converter is unsuccessful to function in the system then the optional converters start operating, to protect the micro-grid system from being completely detached and hence consistency of the system is guaranteed.


2.1.4        Decentralized micro-grid

Decentralized micro-grid makes use of the alteration in the frequency of local grid to regulate the active power production and utilization in the micro-grid. In this regard, the power electronic transformer (PET) permits limited dynamic power flow to the micro-grid, at a needed value established by the utilities. For a rapid diminution in grid power, the decentralized micro-grid controls their production, using the ensuing drop in the neighboring grid frequency as a signal (Yuen et al., 2011).

2.1.5 Voltage control strategy

One of the key setbacks in distributed generation (DG) development is voltage control founded on reverse power. So that the voltage difference may possibly not demean client electrical energy supply quality, voltage of the feeder ought to be sustained within the allowable scope in opposition to distributed generation connection (Luo et al., 2009). Thus, to enhance the voltage profile in allocation set-up with distributed generation, voltage control strategies that integrate present spontaneous power compensator and voltage control mechanism provides the best solution.

2.2.0 Energy management in micro-grid

A micro-grid EMS is control software that can optimally allocate the power output among the DG units, economically serve the load, and automatically enable the system resynchronization response to the operating transition between interconnected and islanded modes based on the real-time operating conditions of micro-grid components and the system status.


2.2.1Centralized energy management (EMS)

Centralized energy management help alleviate and centrally regulate the cost threat for energy supplies as well refocuses site workers on site-level plans.  What’s more, EMS offer all in-house stakeholders with entrée to dependable and wide-ranging cost and application information, which in turn, results to safe impartial, apt and consistent market astuteness (El Moursi et al., 2008). In addition, EMS improves standard site price and application functionality across every site and takes part in energy contracts in compliance with the organization’s permissible tolerances. Finally, EMS promptly incarcerate opportunities in the energy market, especially in an extremely unstable market as well as setting up baselines for carbon emissions, set accurate diminution targets, and validate advancement toward the reductions

2.2.2        Decentralized energy management (DEMS)

Optimization of Energy with DEMS utilizes three devices, which are interconnected in a smart network. According to Luo et al. (2009), this assists the user to save money openly in two ways: through abridged energy optimization outlay and through energy effectiveness. What’s more, by design DEMS delivers predicts for production and use of renewable power. Based on these predicts, the user can draft the time programs for the decentralized production plants (Luo et al., 2009).

2.3.0 Voltage regulation

Contemporary power systems run at a given standard voltages, whereby at these standard values the apparatus operating on these systems are as a result, provided input voltages, within definite approved tolerance limits. Saied (2001) defines voltage regulation in two manners; Regulation up and Regulation Down.

2.3.1 in the electric grid

So as to ensure voltage constancy at various nodes in a system of electrical power, the impedances of the line in the transmission system have to be taken into account. What’s more, cables utilized in underground or overhead lines are produced either of steel, aluminum, copper, alloys. According to Skretas and Papadopoulos (2009), these materials offer little but not insignificant resistance to the electrical current flow when taking into account the covered distances by lines of transmission. In essence, the most universal technique for swapping transmission and delivery of current power are three-phase systems, whereby three alternating currents are conveyed by three circuit conductors that have similar frequency and which arrive at their immediate peak values at distinct times.

2.3.2 Voltage regulation by Load shedding

Looming voltage collapse can repeatedly be shunned by using suitable loads controls, but the conventional type of load control (shedding) is ostracized because of the ensuing end user distraction. However, developments in computer and communications and systems permit more discriminating load control. Entity loads that can be sacrificed temporary can be switched with minimum end user distraction. In essence, the most efficient load shedding methods are not for all time so clear still, but low voltages frequently offer an excellent hint of positions where load shedding would help in alleviating system stress (Hiskens & Gong, 2005).


2.4.0        DC-DC converters

DC to DC converters are vital in electronic appliances like mobile phones and PC, which are primarily furnished with energy from batteries. In essence, such electronic appliances time and again entail numerous sub-circuits, all with their own voltage level requisite distinct from that provided by the battery.

2.4.1Isolated converter

In isolated converter, isolation signifies the presence of an electrical barrier in the midst of the output and input of the DC-DC converter. Arguably, isolated DC-DC converter has a towering frequency converter that presents this barrier, which can endure any voltage from several hundred volts to some thousand volts as is needed for medicinal usage (Baek & Park, 2012). Subsequently, an isolated converter output can be changed to be either negative or positive.

2.4.2        Non-isolated converter

LM317 three terminal linear regulators is the simplest illustration of a non isolated converter, whereby one terminal is for the controlled output, one for uncontrolled input, and the last one for the common (Baek & Park, 2012).  SEPIC converter

The single-ended primary-inductor converter (SEPIC) can operate from an input voltage, which is superior or little as compared to the controlled output voltage. Apart from being capable to operate as both a boost and buck converter, Khateb et al. (2013) posit that the SEPIC as well has minimum dynamic modules, an uncomplicated regulator, and fastened switching waveforms, which offer stumpy sound operation. Besides that, the SEPIC is frequently recognized by its application of two magnetic winding, which can be wound on an ordinary core (Khateb et al., 2013).

Fig 2: SEPIC Converter  Boost converter

Boost converter is another type of DC-to-DC power converter whose input voltage is much less than its output voltage. What’s more, it is in the set of switched-mode power supply (SMPS) having as a minimum one power storage component, two semiconductor switches (a  transistor and a diode) and inductor, capacitor, or the both in connection (Mahery & Babaei, 2013). Furthermore, capacitors filters (occasionally in grouping with inductors) are usually supplemented to the converter output to decrease ripple of the output voltage.


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