This page contains a Flash digital edition of a book.
Renewables & The Grid
One very clean refuse incinerator in a major city has been megawatts in a matter of minutes. If utilities want to see this
shut down after only eight years of operation because people power swing in operation, visit Tennet the grid operator in The
living in the area did not like the noise of the trucks and the Netherlands and watch the power flow on a stormy day on the
look of the facility in their neighbourhood. The facility interconnector with Germany. Because conventional
exceeded every standard that could be applied, and trucks generation does not react as quickly as V-Cent typically does,
were only allowed to deliver refuse from 10 a.m. to 4 p.m., a the grid operator on the transmission network has to deal with
time when few people were home. rapid changes in voltage on the grid. In some cases, where the
penetration of wind or solar is small, the rapid swing is a small
V-Cent part of the overall power flow and can be safely ignored. In
Like the S-Cent facilities, they are connected to the high Texas and Spain this is not the case, where both have almost
voltagenetworkandproducelargeamountsofpower.Also,like lost the transmission grid to blackouts because of wind power.
the S-Cent facilities, they are highly In Texas it was the sudden and
visible on the horizon and cannot be
... in most cases the locations
unexpected drop in wind power
easily hidden. Unlike the S-Cent facilities
they run when the environment is right,
that have the best wind are
production and in Spain it was too
much wind generation on a wonderful
and not when they are needed. For
not the places with a high
spring Sunday when people decided to
example,windhastoblowfastenough– density of people go outside and shut off most of their
andyetnottoofast–inordertogenerate electric devices. Swift action by the grid
power. In most cases they offer power for 7-40% of the time operator saved the grid in both cases – but it was close.
depending on the location and type of resource. These systems Geographically wind blows where it blows and we do not
require some level of other generation to provide support, since have the skills to modify global weather patterns and put the
the power they produce comes and goes on a change in the wind where we want it to generate power. In the main, people
weather, and the load they support may not. The estimate in do not like to live in areas with strong and steady winds. This
Colorado is that it takes 1 megawatt of running gas-fired means that in most cases the locations that have the best wind
generation to support 2 megawatts of wind generation in the are not the places with a high density of people or power
state. This ratio has a big impact on the carbon footprint of the consumption. For the grid operator, that means building
final delivered power. While it is cleaner than a new coal-fired extensions to the transmission grid. High voltage transmission
power plant, the estimate is that to get the equivalent of 2 lines are not cheap – they can cost millions of euros a
megawatts of new coal-fired power plant, 1 megawatt of gas- kilometre. For example, at AEP, one project is budgeted at
fired generation and 2 megawatts of wind generation have to US$5.5 million per mile. Add to the cost the fact that wind
be installed. Large variable central generation can be farms only generate about 40% of the time, and the
monitored by existing SCADA systems and controlled by transmission link to support a plan like the Pickens Plan in the
existing energy management systems in operation by the US (a plan to replace all the fossil generation in the US with
transmission operator today. wind power and use the natural gas that currently makes
What existing systems cannot do is to predict with any level electricity and heats homes to power automobiles) would need
of confidence what the output of wind power will be 24 to 48 to connect to three times the number of megawatts of wind
hours in advance. New systems have to be installed to support power than it would for coal generation. In other words, to use
this kind of forecasting. Forecasting the output of V-Cent is wind to provide ancillary services (e.g. maintaining voltage,
critical, as it determines when to fire up the large fossil plants frequency and the integrity of the Alternating Current (AC)
to support days when the wind is either going to blow too wave form – all required to let a device operate correctly and
strongly or not at all, or, as in the case of photovoltaic, when not burn out – by spreading wind farms over a wide area that
storms are rolling across the service territory hiding the sun. receives strong wind – would cost at least three times the cost
The global understanding of cloud paths and detailed wind of transmission for a new nuclear plant. No one likes large
forecastsislessthan perfect, and assuch, the impactof weather steel towers in their backyard, so you can expect that even if
on V-Cent is likewise less than perfect. people embrace windmills, they will pan the transmission
This less than perfect understanding means that the utility corridors. With these new large transmission links, there are
has to be ready to react to changes in power output on a very issues with power quality and voltage management on the
short timeline. In some cases the swing can be hundreds of transmission network that did not exist before. Proper
worldPower 2009 141
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  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142  |  Page 143  |  Page 144  |  Page 145  |  Page 146  |  Page 147  |  Page 148  |  Page 149  |  Page 150  |  Page 151  |  Page 152  |  Page 153  |  Page 154  |  Page 155  |  Page 156  |  Page 157  |  Page 158  |  Page 159  |  Page 160  |  Page 161  |  Page 162  |  Page 163  |  Page 164
Produced with Yudu - www.yudu.com