WOODWARD EGCP-3 Engine Generator Control Package LS (Load Sharing)

Additional functions include selectable and adjustable process high and low limit switches and alarm activation.

When multiple gensets and EGCP-3 LS controls are connected to a bus in process control mode one unit is automatically assigned as the “Process Master”. It’s process control loop then dictates through the LON network the load levels of other gensets on the bus.

VAR/PF Control

The VAR/PF functions control the reactive power component of the generator in parallel systems. The reactive load mode can be configured for VAR or Power Factor control. The controller compares the reactive load on the generator with an adjustable internal reference and makes corrections to the setpoint of the Automatic Voltage Regulator (AVR) until the desired reactive power is obtained. The reactive power level can be maintained while also controlling real load through the generator breaker. The analog voltage bias output can be directly connected to compatible voltage regulators. The control also has raise and lower contact outputs to activate a voltage regulator MOP when an analog input is not provided on the AVR. The EGCP-3 control has a selectable voltage range alarm that is activated if the analog output to the voltage regulator reaches high or low saturation. The EGCP-3 control also has selectable and adjustable high and low voltage limit switches and alarm outputs.

The EGCP-3 control provides switch inputs to allow raising or lowering the generator voltage reference. The control also provides a 4–20 mA (or 1–5 Vdc) analog input for kVAR/PF setpoint control, if desired. The kVAR/PF reference can also be set through a Modbus or ServLink DDE communication interface.

While the EGCP-3 is controlling unit load to accomplish real load (kW) sharing, the voltage of the generators in parallel will be controlled to accomplish equal Power Factor levels of each generator.

ATS Control

ATS functions are not included in the LS model of EGCP-3. A Master Control (MC) is used to control the mains circuit breakers and local bus circuit breakers to perform ATS functions.

Peaking and Demand Operation

The LS model does not have Peaking and Demand functions. This function is provided from an MC control that provides the interface with the mains(utility) and LS units.

Genset Sequencing

While the details of how to start and stop a genset is determined by the Engine Control sequence, when to initiate a start or stop is the function of the sequence configuration. The starting and stopping of Gensets is closely associated with the configuration of the system bus structure and genset characteristics. All EGCP-3 LS and EGCP-3 MC controls on a common network communicate their operation status and the mains and bus status over a Echelon Network (LON). Systems with up to 16 gensets, and/or four local bus segments, and/or two mains connections for a split bus arrangement can be configured. When automatic connection(s) to the mains is configured an EGCP-3 MC connected to the LON network is required. The user can configure the criteria used to start and stop genset(s) and the priority of which genset is the next to start or stop.

A typical start/stop sequence would be:

 When the units on a bus segment are above a configured Maximum Load Level or above their 100% Load Level, a start command will be given to the next scheduled unit. 

 When the units on this bus segment are below a configured Minimum Load Level, a stop command will be given to the next scheduled unit.

Power and Energy Metering

The digital signal processing techniques are used to provide significantly improved accuracy and speed of response over conventional analog measurement techniques. Accuracy is improved using rapid sampling of the voltage and current signal waveforms and developing a true RMS measurement. Measuring true RMS power allows optimal accuracy, even in the presence of power line distortions.

The PowerSense board receives the PT and CT inputs for both the generator and bus for calculation of parameters for the EGCP-3 to use in system control. The algorithms used are based on IEEE 1459-2000. For the generator and bus the following parameters are provided: Hz, Vac, Amps, W, VA, VAR, PF, Phase, Voltage harmonics, Current harmonics, Negative Phase Sequence Voltage, Negative Phase Sequence Current.

Available for selection at the 4–20 mA analog outputs: Synchroscope, Generator metering, Mains metering

Protective Relaying

The PT and CT inputs were designed for accurate voltage and current monitoring in applications of display and control. They are not designed for high speed,   sub-cycle, or cycle-to-cycle protective relaying though time delay protective relaying can be used.

The EGCP-3 should not be used as the only means for detecting voltage or current disturbances, dead bus conditions, or overcurrent conditions. The generator should be equipped with a sync check relay, circuit breaker, and other fast-acting protective relays as required by local codes and practices to protect against damage to the generator with possible personal injury, loss of life, or property damage. The sync check relay, circuit breaker, and other fast acting protective relays must be totally independent of the EGCP-3.