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The generator capability curve described the capability real and reactive power capability of a generator. Real power is plotted on the horizontal axis, while reactive power is plotted on the vertical axis.
A reactive capability curve consists of three curved segments. One segment is the arc of a circle centered at the origin of the reactive capability curve. Because the radius of that circle is the apparent power, S (in MVA), it is based on the thermal heating limitations inherent in the stator winding and reflects the fact that the stator limitation is based on current alone.
The second segment is an arc of a circle centered on the Q axis - the arc joins the positive Q axis with the constant MVA portion of the curve, and defines the upper boundary of reactive power OUT of the generator. It is the arc of a circle because it also reflects current-based heating; the critical difference is that the limitation described is that of the rotor winding.
The third segment joins the negative Q axis (representing reactive power into the machine) with the constant MVA portion of the curve. This segment reflects end-ring heating while in underexcited operation.
When you change the tap on the generator step up transformer, you will change the reactive output of the generator. Remember that reactive (VARS) always flow downhill in voltage - from higher voltage to lower voltage. So if you change the tap on the transformer to produce a lower open-circuit secondary voltage, the reactive output of the generator will increase. Conversely, if you change the tap to cause a higher open-circuit secondary voltage, the reactive output of the generator will decrease.
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How do you study capability curve of generator?
Generator Capability Curve study
Why alternator power factor 0.8?
In terms of generators, the alternate power factor is generally 0.8 for most models. This factor is defined as the power needed to operate within the limits of he generator capability curve.
How do you define the synchronous generator capability limiters?
SYNCHRONOUS GENERATOR CAPABILITY LIMITTsynchronous generator capability limiters are as follows 1.MVA or armature current limit of generator: this depends on the cooling system of generator so that temperature rise in generator is limited to safe value.depending on cooling system effectiveness and temperature limit for the insulation used in generator, MVA limit is decided.2.MW limit: this is determined by the power output capacity of prime mover to which generator is connected.3.rotor angle limit: this is related to stability of generator which is synchronised to the grid.ideally this could be 90 degree, but in practice this is limited to70 degree so as to have better stability margin in transient and dynamic condition.the generator falls out of synchronism in trasient condition if rotor angle is close to 90 degree.4. rotor current limit: the field winding placed on rotor has got limited current carrying capacity, beyond which it may burn .so this limit is used.all these limitters make capability curve of g generator within which the generators operates safelyr. k.niranjanemail id: rkniranjan@yahoo.com
Importance of load characteristics of a generator?
I assume this is asking about the capability curve of a generator. A generator can only produce so much actual power (kW) at a specific power factor. As power factor changes, the amount of current flowing that is due to reactive power will also change. The total current Ix (reactive power) + Ir (real power) will cause heating in the generator, and so the generator can only kick out so much current, be it real power or reactive power. Reactive power is used to control the voltage (drag it down, or push it up) and change phase angles to push more power down specific lines. If the load on a generator is such that it's expected to generate power outside its' capability curve, terminal voltage may begin to sag (which will cause the generator output power to be less, potentially exacerbating the problem), or may float too high (potentially damaging equipment). Excessive heating in the generator can also result, and protective devices may kick in to trip the generator off line.
How to draw capability diagram of synchronous generator using matlab?
The Capability Diagram Normally, the generator meets all the voltage and frequency requirements of the grid. This can be achieved with two closed -loop controllers # Change of excitation current of the rotor or as so called the AVR # change of fuel supply to the turbine or as so called the GOVERNER But in order to prevent damages caused by high temperature or asynchronous operation, several limitations and design criteria are installed to determine the operating zone of the generator These limitations are: # excitation current (rotor current ) limitation # Stator current limitation # load angle( not the power factor) limitation According to these limitations, the designers of the generator draw the capability curve at certain cold air temperature A circle with the radius of the maximum excitation current limitation, another circle with maximum stator current. The point where these two circles intersect is called the "Design point" of the generator.
Why electric generator drop the load?
Too much load for the generator, the generator began to under speed / overspeed, the governor / part of the generator went into failure, the generator capability was not up to the requirements placed by the system (needing to push out/pull in too many VARs), etc. there are many reasons for a generator to drop a load. Because a load dropped, this does not infer that the generator was the cause either (fault on the system, system instability limits reached, system protection tripped - non-generator related protection).
What is compounding curve in synchronous motor?
The operation of a synchronous generator delivering power to a constant power-factor load is demonstrated by means of compounding curves. A compounding curve shows the field excitation needed to maintain rated terminal voltage as the load is varied.
Advantages and disadvatages of a self excited induction generator?
The main disadvantage should be obvious - when the output voltage of the generator is used to provide field current to the generator....what happens if the output voltage sags? If the output voltage becomes depressed, the output power of the generator is compromised (becomes less and less), this in turn can cause the output to become more depressed, leading to an incrementally decreasing output capability. The main advantage is cost savings.
What is the cone?
The surface generated by a straight line, the generator, passing through a fixed point, the vertex, and moving along a fixed curve, the directrix.A right circular cone.
What information is found on transformer nameplate?
The plate should as a minimum show the working voltage, volt-amp capability and the rpm of the generator. Other optional information is the manufacturer and serial number.
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