DEIF LSU-112DG Load sharing, paralleling & operation

LSU-112DG

Load sharing, paralleling & operation

DEIF’s load sharing units offer load sharing in various ways between generators and interfaces to a governor through an electronic potentiometer (EPQ96-2 or EPN110DN).

DEIF’s load sharing units offer load sharing in various ways between generators and interfaces to a governor through an electronic potentiometer (EPQ96-2 or EPN110DN).

Suitable for control of diesel and gas generators, for instance, they can control the power unit in stand-alone mode (performing frequency control) or parallel with other power units (performing frequency and power control).

The units have built-in power and frequency transducers that enable connection of external equipment. Constant power or isochronous mode is also possible. Speed control is conducted by two relays.

Variants

LSU-112DG

Frequency and power control

LSU-113DG

Frequency and power control

With -P>

LSU-114DG

Frequency and power control

With start/stop

LSU-122DG

Reactive

U and Q control

Application

The LSU-112DG is a control unit for control of the prime

mover in a power unit.

The LSU-112DG can control the power unit  –  –  –

in stand-alone mode, performing frequency control

parallel with grid, performing power control

parallel with other power units, performing frequen

cy and power control

The unit is designed for connection to a mechanical

speed governor, however in conjunction with the DEIF

electronic potentiometer type EPN-110DN or EPQ-96 it

can control electronic speed governors as well.

The LSU-112DG has a built-in frequency transducer. If

a very stable frequency is wanted, an external frequen

cy transducer common for all the LSU-112DGs in the

power plant can be connected. If a number of power

units are to be synchronised to the busbar at the same

time, the frequency may likewise be controlled external

ly.

Function

The LSU-112DG is measuring the voltage and the

current from which the frequency and the power pro

duced by the power unit are measured. The built-in

power transducer is based on an I x cos phi principle.

The following couplings are available: – –

1W(4) –  single phase

1W3  – 1-element 3-phase, 3-wire, balanced load

If unbalanced load can be expected, an external power

transducer with an output of 4 to 20 mA can be con

nected to the LSU-112DG. In this case the built-in I x

cos phi transducer is automatically interrupted.

The power and frequency measured by each LSU

112DG are fed to two paralleling lines for comparison

with the frequency (FS) and power (PS) of the other

connected LSU-112DG.

If L1 or L2 is disconnected from the LSU-112DG at the

same time as a power unit in a power plant is discon

nected from the power line (busbar), built-in relays in

the LSU-112DG ensure that the power output and the

frequency output of the associated unit are disconnect

ed from the paralleling lines. Likewise the power and

frequency outputs are disconnected if the auxiliary

voltage to the LSU-112DG is disconnected.

The LSU-112DG is equipped with an unload input.

When activated this input will control the power unit to

zero power, and at the same time the power output of

the LSU-112DG is disconnected from the paralleling

line.

The calibration of the LSU-112DG is done so it matches

its power unit. This means that load sharing between

power units with different size will be performed accord

ing to the actual size of the individual power unit in the

plant. For example a 100 kW PU and a 150 kW PU

running in parallel will share a total load of 125 kW into

50 kW and 75k W. If the 150 kW PU is derated to 100

kW by means of the DERATING potentiometer on the

front of the LSU-112DG, the load in the above example

will then be shared equally between the two power

units.

Regulator output

The unit is provided with two contact outputs for speed

control:

Power and frequency control:

The regulating speed of the servomotors for the prime

mover is controlled by the built-in P controller of the

LSU-112DG according to its setting for:

TN (min. ON time):

The min. duration of the control pulse when inside the

proportional band Xp.

XP (proportional band):

The zone within which the pulse/pause ratio changes

proportionally to the frequency/power deviation from the

required value.

TP (period time):

The time between the beginnings of two subsequent

relay pulses.

Deadband:

The zone within which no control pulses are emitted.

Self-monitoring

The LSU-112DG is equipped with a self-monitoring

function. The function supervises the built-in micro

controller and hereby verifies if the programme is run

ning correctly. The green LED marked “POWER” is

connected to this function. Constant green light indi

cates that the supply voltage is accepted and the unit is

running correctly. Flashing green light 2-3 Hz indicates

that the supply voltage is accepted but the unit is run

ning incorrectly. In this situation the status output termi

nals 17 and 18 are activated (open).