What is the standard

A standard is an agreed way of doing something .

1. It could be about making a product , managing a process , delivering a service or supplying materials.
2. Standards can cover a huge range of activities undertaken by organizations and used by their customers .
3. Standards are the wisdom of people with expertise in their subject matter and who know the needs of the organizations they represent-people such as manufacturers , sellers , buyers , customers , trade associations , users or regulators . The standard can provide a reliable basis for people to share the same expectations about a product.

 This helps to : 

• Facilitate trade 
• Provide a framework for achieving economies , efficiencies and interoperability
• Enhance consumer protection and confidence 

As defined by ISO , standards refer to "documents , established by consensus and approved by recognized body , that provides , for common and repeated use , rules , guideline or characteristics for activities or there results , aimed at the achievement of the optimum degree of order in a given context " .

"Both standard and standardization are important treasures for human society , playing a role in all fields in modern society . One often cannot feel the standards all around but will ask question how a standard was developed if issues a rise . Both of these have become the unique infrastructure for economic and social development and function as a platform for technological innovation and industrial development".

Different types of standard  

• A quality management standard to help them work more efficiently and reduce product failures .
• An environmental management standard to help reduce environmental impacts , reduce waste and be more sustainable.
• A health and safety standard to help reduce accidents in the workplace .
• An IT security standard to help keep sensitive information secure .
• A construction standard to help build a house .
• An energy management standard to help cut energy consumption .
• A food safety standard to help prevent food from being contaminated .
• An accessibility standard to help make buildings accessible to disabled users .
• An interoperability standard to ensure that bank and credit cards fit into ATMs and can be used throughout the world .

Standardization

Is the process of developing and implementing the technical standards. Standardization can help to maximize compatibility , safety , or quality .

Standardization is implemented greatly when companies release new products to be successful , many devices coming out have different standard types of connection . This allows consumers to use their new items along with what they already own . By using standardization , groups can easily communicate through the set guidelines , in order to maintain focus .

Standardization aims 

The main benefit of a standard is achieving the economical benefit that could be reached by the establishment of the interoperability of different systems or by the re-use of interoperability of resources . Interoperability and quality development can be called the two main purposes of standardization to gain economical benefit .

Purpose of standardization 

The purpose of standard abbreviations and guidelines is to provide a uniform reference when there is a need to condense address data. Purpose of standards can be summarized as : 

• Developed based on guiding principles of openness , balance , consensus , and due process .
• Established in order to meet technical , safety , regulatory , societal and market needs .
• Helping for technological innovation and global market competition .

Standardization Techniques

There are typically four different techniques for standardization : 

• Simplification or variety control 
• Codification 
• Value Engineering 
• Statistical process control 

Types of standardization 

• Emergence Standard as de facto 
• Written by a standards organizations 
• Written by a government or regulatory body
• Written by a corporation, Union , trade association ,etc.

Essential Components Of Power System

  (Electric power is produced at generating stations (GS 

  and transmitted to consumers through a complex network of individual components , including transmission lines ,transformerand switching devices

It is common practice to classify the transmission network into

      the following subsystems : 

 Transmission System 

Subtransmission System 

Distribution System 

Transmission System 

interconnects all major generating stations and main load centers in the system . It forms the backbone of the integrated power system and operates at the highest voltage levels (typically, 230 KV and above ). The generator voltages are usually in the range of 11 to 35 KV . These are stepped up to the transmission voltage level , and power is transmitted to transmission substations where the voltage are stepped down to the subtransmission level (typically, 69 KV to 138 KV) . The generation and transmission subsystems are often referred to as the bulk power system 

Subtransmission System 

Transmits power in smaller quantities from the transmission substations to the distribution substations . Large industrial customers are commonly supplied directly from the subtransmission System . In some systems, there is no clear demarcation between subtransmission and transmission circuits. As the system expands and higher voltage levels become necessary for transmission, The older transmission lines are often relegated to subtransmission function

Distribution System 

Represents the final stage in the transfer of power to the individual customers. The primary distribution voltage is typically between 4.0 KV and 34.5 KV . Small industrial customers are supplied by primary feeders at this voltage level . The secondary distribution feeders supply residential and commercial  customers at 120/240 V 

Small generating plants located near the load are often connected to the subtransmission or distribution System directly 

 Interconnections to neighbouring power systems are usually formed at the transmission system level 

Small generating plants located near the load are often connected to the subtransmission or distribution system directly

Interconnections to neighbouring power systems are usually formed at the transmission system level 

The function of an electric power system is to convert energy from one of the naturally available forms to the electrical form and to transport it to the points of consumption. Energy is seldom consumed in the electrical form but is rather converted to other forms such as heat , light, and mechanical energy 

The advantage of the elec-trical form of energy is that it can be transported and controlled with 
relative ease and with a high degree of efficiency and reliability 

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Paralling Generators on power System and his required

The major advantages for operating synchronous generator
parallel are as follows

 The reliability of the power system increases when many 

generators are operating in parallel , because the failure of any one of them does not cause a total power loss to the loads

When many generators operate in parallel, one or more of them can be taken out when failures occur in power plants or for preventive maintenance

  If one generator is used, it cannot operate near full load (because the loads are changing), then it will be inefficient. When several machines are operating in parallel, it is possible to operate only a fraction of them. The ones that are operating will be more efficient because they are near full load

The Conditions Required for Paralleling

 illustrates a synchronous generator G1 supplying power to a load with another generator G2 that is about to be paralleled with G1 by closing the switch S1. If the switch is closed at some arbitrary moment, the generators could be severely damaged and the load may lose power. If the voltages are different in the conductors being tied together, there wil ofl be very large current flow when the switch is closed

This problem can be avoided by ensuring that each of the three phases has the same voltage magnitude and phase angle as the conductor to which it is connected. To ensure this match, these

 paralleling conditions must be met

The two generators must have the same rms line voltages -

 The phase sequence must be the same in the two generators -

The two a phases must have the same phase angles -

 The frequency of the oncoming generator must be slightly higher than the frequency of the running system

The General Procedure for Paralleling Generators

If generator G2 is to be connected to the running system , the following steps should be taken to accomplish paralleling

 The terminal voltage of the oncoming generator should be adjusted by changing the field current until it is equal to the line voltage of the running system

2. The phase sequences of the oncoming generator and of the running system should be the same

The phase sequence can be checked by using the following methods

a.    A small induction motor can be connected alternately to the terminals of each of the two generators. If the motor rotates in the same direction each time, then the phase sequences of both generators are the same. If the phase sequences are different, the motors will rotate in opposite directions. In this case, two of the conductors on the incoming generator must be reversed

b.   illustrates three lightbulbs connected across the terminals of the switch connecting the generator to the system. When the phase changes between the two systems, the lightbulbs become bright when the phase difference is large and dim when the phase difference is small. When the systems have the same phase sequence, all three bulbs become bright and dim simultaneously. If the systems have opposite phase sequence, the bulbs get bright in succession

The frequency of the oncoming generator should be slightly higher than the frequency of the running system. A frequency meter is used until the frequencies are close; then changes in phase between the the generator and the system are observed

The frequency of the oncoming generator is adjusted to a slightly higher frequency to ensure that when it is connected, it will come on-line supplying power as a generator, instead of consuming it as a motor

Once the frequencies are almost equal, the voltages in the two systems will change phase relative to each other very slowly. This change in phase is observed, and the switch connecting the two systems together is closed when the phase angles are equal . A confirmation that the two systems are in phase can be achieved by watching the three lightbulbs. The systems are in phase when the three lightbulbs all go out
 because the voltage difference across them is zero
This simple scheme is useful, but it is not very accurate. A synchroscope is more accurate. It is a meter that measures the difference in phase angle between the a phases of the two systems . The phase difference between the two a phases is shown by the dial. When the systems are in phase (0° phase difference), the dial is at the top. When they are 180° out of phase, the dial is at the bottom

The phase angle on the meter changes slowly because the frequencies of the two systems are slightly different. Since the oncoming generator frequency is slightly higher than the system frequency, the synchroscope needle rotates clockwise because the phase angle advances. If the oncoming generator frequency
is lower than the system frequency, the

(c.  Machine voltage now equal to system. Voltage waves out of phase but frequency being increased by increasing speed of prime mover. (d) Machine voltage now equal to system, in phase and with equal frequency. Synchroscope shows 12 o’clock. Switch can now be closed

needle rotates counterclockwise. When the needle of the synchroscope stops in the vertical position, the voltages are in phase and the switch can be closed to connect the systems

However, the synchroscope provides the relationship for only one phase. It does not provide information about the phase sequence

The whole process of paralleling large generators to the line is done by a computer. For small generators, the operator performs the paralleling steps

Frequency-Power and Voltage-Reactive Power Characteristics of a Synchronous Generator .The mechanical source of power for the generator is a prime mover such as diesel engines or steam, gas, water, and wind turbines. All prime movers behave in a similar fashion. As the power drawn from them increases, the rotational speed decreases. In general, this decrease in speed is nonlinear. However, the governor makes this decrease in speed linear with increasing power demand.

Thus, the governing system has a slight speed drooping characteristic with increasing load. The speed droop (SD) of a prime mover is defined by where nnl is the no-load speed of the prime mover and nfl is the full-load speed of the prime mover. The speed droop of most generators is usually 2 to 4 percent. In addition, most governors have a set-point adjustment to allow the no-load speed of the turbine to be varied
Since the electrical frequency is related to the shaft speed and the number of poles by

The reactive power Q has a similar relationship with the terminal voltage VT . As pre- viously described, the terminal voltage drops when a lagging load is added to a synchronous generator. The terminal voltage increases when a leading load is added to a synchro- nous generator.  illustrates a plot of terminal voltage versus reactive power

This plot has a drooping characteristic that is not generally 

linear, but most generator voltage regulators have a feature to make this characteristic linear

When the no-load terminal voltage set point on the voltage regulator is changed, the curve can slide up and down

The frequency-power and terminal voltage-reactive power characteristics play important roles in parallel operation of synchronous generators. When a single generator is operating alone, the real power P and reactive power Q are equal to the amounts demanded by the loads

The generator’s controls cannot control the real and reactive power supplied. Therefore, for a given real power, the generator’s operating frequency is controlled by the governor set points, and for a 

given reactive power, the generator’s terminal voltage VT is controlled by the field current

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