Transmission & distribution | Control
Converting unused generators It is entirely possible to convert an unused large generator into a synchronous condenser, and there are a number of these converted generators operating successfully. However, this should be approached with caution as the equipment to be converted will, by definition, be old technology and its actual condition unknown. Before starting a project, it is advisable to have the condition of the generator assessed thoroughly, such as by ABB’s Lifetime Expectancy Analysis Program (LEAP) service.
Excitation
Synchronous condenser
Pony motor
Above: Figure 4. Starting a synchronous condenser
inertia, additional fault current and reactive power.
● Transmission systems
For transmission system operators (TSOs), synchronous condensers mitigate protection problems due to decreased SCL, PLL instability, rapid changes in power flow, system stability problems, power system splits due to different inertia levels, and other issues. They can facilitate inertia planning, provide additional short circuit capacity to strengthen the network and remedy voltage collapse during heavy load peaks. SCs can also mitigate transient faults when integrating large wind farms and enable higher system availability through redundancy when multiple units are installed.
To reduce the risk of power oscillation, SCs can be remotely deployed in decentralised grids.
● Distribution systems
For distribution system operators (DSOs), synchronous condensers mitigate large variations in SCL between day and night periods and manage deeper voltage dips caused by reduced SCL and general power quality problems. They can be configured to supply “switchable” fault current support during high/low load times. SCs also supply fault current and inertia during island operation, such as in microgrids.
● Industrial applications In industrial applications synchronous condensers resolve power quality issues in weak grids, counteracting voltage dips that cause variable speed drives (VSDs) to trip and interrupt production processes. They Increase fault current and reduce the transfer of power quality issues (flicker, harmonics, unbalance) to the grid. Synchronous condensers can mitigate voltage stability issues associated with heavy industries like mining, especially when fossil fuel generators are phased out.
Other capabilities include supplying short circuit capacity to strengthen the network and prevent voltage collapse during heavy load peak. They also increase fault current and reduce problems with motor-starting and demanding loads like gearless mill drives and furnaces at mines.
14 | May 2021 |
www.modernpowersystems.com
In any case, modern SCs will be smaller and simpler, enabling them to be installed in any location. They also come with the benefits of modern control and communication technology. Maintenance requirements are very low, as they are simpler and smaller than traditional power generators. Furthermore, SCs are usually applied as two or more smaller units for redundancy.
Synchronous condenser configuration
ABB supplies synchronous condensers in ratings up to 80 MVAr and 3 to 15 kV system voltage. The preferred voltage is a matter of optimisation, since the network voltage is usually much higher, so a step-up transformer is used. Higher outputs are reached by using several units in a standardised module concept. This configuration offers better redundancy and availability compared to one large unit.
The construction of the SC is not substantially different to a synchronous generator as it features a salient pole rotor, brushless excitation and epoxy resin insulated stator windings. The machine is usually water cooled, as this is one of the most effective ways to dissipate the heat losses and it is designed to be used both indoors and outdoors in different ambient conditions. However, other cooling options, such as air-to-air cooling, are also possible.
For starting, a small pony motor of about 200-300 kW is coupled to the SC (see Figure 4). It is controlled by a drive which ramps up over a few minutes to bring the speed of the SC into synchronous operation, usually at 1500 rpm.
The excitation system is then started and at the right moment the synchronization procedure will switch the machine online, ready to support the network
Examples of synchronous condenser applications Synchronous condensers are being deployed in grid support applications around the world including:
● Darlington Point solar farm Two ABB synchronous condensers have been installed as an integral part of the Darlington Point solar farm (see Figures 2a and 2b). They help stabilise the local power grid as the penetration of renewable energy increases in a critical area of New South Wales. The facility started operation in August 2020, and with a projected annual output of 685 000 MWh, it is currently the largest solar farm connected to Australia’s grid.
The synchronous condensers contribute to short circuit capacity so that the network can easily ride through any fault conditions and avoid loss of power in the region. This is especially important as the solar farm is located in an area where it is challenging for new projects to meet the stringent connection requirements.
● Antapaccay copper mine
In 2013, ABB completed the commissioning of two synchronous condensers and harmonic filters for Xstrata Copper’s Antapaccay project in southern Peru. The project is located in a remote area and is connected by a long power transmission line. The synchronous condensers ensure accurate and dynamic power factor compensation for safe and reliable operation at the remote mine. By integrating SCs and harmonic filters, the harmonics are mitigated and short circuit levels improved, optimising Antapaccay’s productivity and energy efficiency.
● High-inertia solution, Lister Drive In February 2021, ABB was awarded a contract by Statkraft to design, manufacture and install
Above: Figure 5. Artist’s impression of the Lister Drive Greener Grid project
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45
