POWER SYSTEM NETWORK RELIABILITY
DIFFERENT CONTROL TECHNIQUES AND INTERACTION OF PROCESS PARAMETERS e.g. feed forward, cascade, ratio, over- ride controls Batch continuous process controls
The reduction in inventories, coupled with changing market demands and fluctuations in raw material and energy prices, requires a process plant to respond fast for optimum operation. In order to change the production rates or product grades, flows need to change throughout the
plant. Feedback loops eventually finds the right flows, but much important time is lost and product quality may suffer in the interim. Feed forward control offers ability to make the plant automation system respond immediately. Feed forward control can also compensate for composition, pressure and temperature upsets prior to, they have a significant impact on product quality.
Feedforward can primitively move a process to match the flows and conditions (e.g., temperature and composition) of all important process streams on a process flow diagram (PFD) for a given product and total production rate, thereby enforcing material, component, charge, and the energy balances for fed-batch and some continuous processes. Plant-wide flow feed forward control provides the fastest possible and least disruptive transition to optimum operating conditions.
Multistage sampling is a complex form of cluster clamping. Cluster sampling is that type of sampling which involves dividing the population into groups (or clusters). One or more clusters are chosen at random and everyone within the chosen cluster is sampled.
Using all the sample elements in all the selected clusters may be prohibitively expensive or not much necessary. Under these circumstances, multistage cluster sampling becomes useful. Instead of applying all the elements contained in the selected clusters, the researchers randomly select elements from each cluster. Construction of the clusters is the first stage, then deciding what elements within the cluster to use is the second stage. The technique is used often when a complete list of all members of the population does not exist and is inappropriate.
In some cases, several levels of cluster selection may be applied before the final sample elements are reached. For example, take the household surveys conducted by the Australia begin by dividing metropolitan regions into ‘collection districts’, and then selecting some of these collection districts (first stage). The selected collection districts were then divided into blocks, and those were chosen from within each selected collection district (second stage). Next, dwellings were listed within each selected block, and some of these mentioned dwellings are selected (third stage). This method means that it is totally not necessary to create a list of every dwelling in the region, only for the selected blocks.
These two fundamental principles of charge interactions will be used throughout the unit to explain the vast array of static electricity phenomenon. There are two types of electrically charged objects – those that contain more protons than electrons and are said to be positively charged and those that contain less protons than electrons and are said to be negatively charged. These two types of electrical charges – positive and negative – are said to be opposite types of charge. And consistent with the fundamental principle of charge interaction, a positively charged object will attracts a negatively charged object. The oppositely charged objects will exert an attractive influence upon each other. In contrast to the attractive force existing between two objects with opposite charges, two objects that are having like charge will repel each other. That is,here a positively charged object will exert a repulsive force upon a second positively charged object. This repulsive force pushes the two objects apart from each other. Similarly, a negatively charged object will exert a repulsive force upon a second negatively charged object. Objects with like charge on them repel each other.
These were some important terms in power system network reliability.
SOME EXPECTED QUESTIONS ARE:
ques 1) How to improve sampling?
ans- This can be improved through pulse width modulation techniques.