Key Points

  • Engineering, Procurement, Construction and Commissioning “Turnkey” project
  • Designed and specified for continuous duty operation
  • Medium Voltage feed into client’s 33kV consumer substation
  • Automatic control of relevant switchgear in consumer substation
  • Synchronization of the diesel power plant with the utility supply (MV switchgear)
  • Cogeneration with mains – full load exercise runs, load reduction on request, peak power demand mitigation
  • Protection includes cable and transformer differential protection; as well as NER-based grounding
  • IP55 alternators with LV/MV voltage step-up transformers
  • Containerized indoor switchgear and containerized plant control room
  • All site parameters available on Modbus TCP/IP

Superwatt engineered, procured and constructed a standby power plant:

  • The project is based on seven 2MVA prime power generators, each configured for 1300kWe continuous duty operation – 9.1MWe continuous duty generation capacity
  • Four 4MVA voltage step-up transformers to 33kV system voltage
  • Air-conditioned containerized Medium Voltage switchgear with four transformer incomers and one plant feeder
  • Air-conditioned containerized power plant control console with user interface for each generator as well as the power plant’s master controller and its associated user interface
  • Consumer substation control panel with synchronizing control over two utility incomers and one generator plant incomer. Panel equipped with graphics display unit for each of the three incomers  
  • Bulk fuel (46kl) and oil (23kl) supply tanks as well as 23kl used engine oil recovery tank
  • Centralized fuel and oil pumps with associated filters and coalescer feeding the fuel and oil distribution manifolds

Features/ Highlights

  • The power plant’s layout design and physical placement allows for future expansion to a maximum cluster size of 28 generators
  • V16 Cummins engines coupled to AvK alternators with IP55 enclosures
  • The AvK alternators are equipped with air-to-air heat exchangers which protect the alternator windings from the harsh environmental conditions associated with the site
  • The IP55 AvK alternators are dual bearing machines (reduced dead weight on engine fly-wheel; use of elastic coupler between engine and alternator)
  • Specified for high ambient temperature operation without derating of the electrical power output of the power plant
  • Engines equipped with oil pre-lube pumps to reduce engine wear during starting
  • “Closed” oil handling system – used engine oil is recovered via a permanently installed pump and manifold system into a used oil recovery tank – new replacement oil is automatically measured and supplied from the bulk oil tank to the relevant engine. (Expedites and simplifies oil drain procedure; reduces risk of oil spillage)
  • Automatic engine sump oil level management while engine is running (automatic oil intake from bulk oil supply system; visual indication of sump oil level)
  • Three phase engine heaters with coolant circulating pumps
  • Fiber optic interconnections which leaves each generator controller fully isolated from the ‘outside world’. (Resilient communication in the presence of electrical noise and virtually immune to lightning strikes)
  • Withdrawable alternator synchronizing and protection air circuit breakers
  • Alternators electrically isolated from each other (with step-up transformers). Each alternator is ground referenced through its own NER (neutral earth resistor) which limits possible ground fault currents
  • Standby power plant voltage is 33kV; stepped up from the 400V alternator voltage to 33kV by four step-up transformers rated 4MVA each (continuous duty)
  • The 33kV system is ground referenced via a 150ohm NER to limit ground fault currents. A dedicated protection relay monitors the health status of the NER
  • Each step-up transformer is protected by a modern (digital) transformer protection relay which also incorporates differential protection. A protection trip-event will isolate the transformer completely (MV-side and LV-side)
  • Air-conditioned Medium Voltage switchgear container with 33kV extensible Schneider switchgear. The 630A/33kV bus and 630A feeder to the consumer substation will support future power plant capacity increase up to 36MVA. The container is equipped with an 110Vdc BTU for the motorized switchgear. A pilot wire protection relay is installed for the feeding cable to the consumer substation
  • Air conditioned power plant control room (Control Container) offers a one stop control and monitor point for the power plant. The control console has a graphic user interface for each generator and also a display unit for the plant support services, generated power, etc. The site’s master controller and transformer protection relays are also integrated into the control console
  • The power plant has fully automatic control of the incoming switchgear in the consumer substation; but only if autonomous/automatic operation is selected on each of the two utility incomers as well as the generator plant incomer. The consumer substation switchgear is wired to a dedicated control panel inside the substation. This panel is in effect a logical extension of the power plant’s master controller. Signal connectivity is via fiber optic links to the control container
  • The power plant’s control system offers generator-on-generator synchronization (utilizing the 400V alternator breakers) as well as mains synchronization over the three incoming breakers in the consumer substation. Backup sync protection relays and extensive interlocking has been implemented in the consumer substation to reduce risk to personnel and equipment
  • The control system logic is programmed on ComAp controllers exclusively. This approach allows for a simply ‘all in one’ development environment without the need to integrate third party logic controllers into the system
  • NamPower approved the diesel power plant installation for parallel to mains (PtM) operation. As a result the system has been programmed to allow cogeneration on demand as well as soft (seamless) load transfer between utility power and generator power if/when required. The number of active generators (selected in the control container) determines the contribution of the generator plant when operating in cogeneration mode
  • Ethernet connectivity of all controllers on site (via optical fiber links) facilitate integration with the client’s SCADA system (Modbus TCP/IP). Provision was also made for remote diagnostics and maintenance via Internet access on a need-be basis (in order not to compromise the client’s network security)
  • Superwatt partnered with local contractors/suppliers during the site construction phase thereby investing in the skills of local industry and contributing to the local GDP
  • Long term maintenance and service support has been integrated with existing (local) service partners in current employ of the client, so ensuring quick turnaround times for both routine servicing and breakdowns
  • Compliance with Environmental impact and Health and Safety requirements during the construction phase. The project was completed without environmental damage and with a clean health and safety record
  • Superwatt used in house expertise for all logistics including clearing and forwarding so ensure statutory compliance with all the relevant government bodies