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load flow calculation methods in ETAP Power Station

askramadhan — Thu, 09 Jul 2009 18:21:11 +0000

in this section we will describe numerical methods to solve load flow problems.The principal information obtained from the load study is the magnitude and phase angle of the voltage at each bus and the real and reactive power flowing in each line.[1]

the solution to the power flow problem begins with identifying the known and unknown variables in the system. The known and unknown variables are dependent on the type of bus. A bus without any generators connected to it is called a Load Bus. With one exception, a bus with at least one generator connected to it is called a Generator Bus. The exception is one arbitrarily-selected bus that has a generator. This bus is referred to as the Slack Bus.[1]

ETAP Power System gives 3 different methods to solve load flow. newton-raphson, fast decoupled, and accelerated gauss siedel. numerical concepts for this three methods can be seen in [2],[3]

to select these methods, just open the edit study case. after that you can choose the method you want in info menu.

in alert menu, you can determine critical and marginal loading in elements in your network. critical loading means the limit exceeds and must be solved. marginal loading means that the values exceed but is still in permissible state. usually values of critical and marginal loading describes in grid code of your power system.

reports of load flow solution show in this example below,

1.accelerated gauss siedel

2.fast decoupled

3.newton-raphson

from this report we can see that with precision about 0.00001, shortest number of iterations when we use newton- raphson method it only iterate about only to iterations. the important this we must see is system mismatch. definition mismatch is differences between the specified/schedule value and the calculated value. if the differences is bigger than 0.1 MW, there will be an indication calculation report automatically.

Detuned reactor calculation

askramadhan — Wed, 08 Jul 2009 05:55:26 +0000

Detuned filter are designed to used for power factor correction in systems where harmonics are generated by nonlinear loads, each step of detuned filters consists of a capacitor and a series reactor connected in series. These two from a series resonant circuit tuned at a frequency below the lowest harmonics frequency present in the system normally the 5th (250Hz) . Detuned filter also removes lower order harmonics from the system to some extent. This will helps to offset the Resonance effect for longer trouble free operation.[1]

this subject will calculate detuned reactor when installed series with capacitor bank. this calculation also prove that detuned reactor can improve reactive power output to system.

calculation of detuned reactor in details

calculation of detuned reactor in details. (mirror )

Short Circuit ETAP Power System (1)

askramadhan — Sun, 05 Jul 2009 15:02:37 +0000

In power system operation, energy that produced in power plans have to deliver to load center with a good quality and without any problem.many problems occur in power systems. the most common fault in power system is short circuit. short circuit in an electrical circuit is one that allows a current to travel along a different path from the one originally intended. The electrical opposite of a short circuit is an “open circuit”, which is an infinite resistance between two nodes. It is common to misuse “short circuit” to describe any electrical malfunction, regardless of the actual problem.[1]

ETAP Power system provides Short circuit module that enables engineer to predict, analysis , and solve when this fault occurs in power system.

this article enables you to use short circuit module in ETAP circumstance. the first one is that you have a Short circuit module in your license.

1. Select the short circuit module in toolbar

2. in edit study case, you can select any busbar that you want to S.C and you can choose either ANSI or IEC standard.

3. Select one of simulation that you want simulate.

this options include short circuit 3 phase fault , LL fault , LLG fault , LG fault in 30 cycle , 4 cycle and 0.5 cycle.

after we select a simulation, then the reports and in ETAP Power system look like this: