IEEE Power & Energy Magazine - November/December 2021 - 87

This is partially because electricity consumption dropped
considerably in all countries due to the pandemic. In 2020,
Europe surpassed a 15% share of wind energy and 8%
solar. The United States achieved 8% wind and 3% solar,
and China reached 9.5% wind and solar, with Qinghui and
Ningxia surpassing 30%.
The status of VRE, as the average and highest instantaneous
shares of demand and generation capacity, are depicted
in Figure 1, showing how high hourly shares of VRE can
be when the average VRE share is close to 40-50% of electricity
consumption. The graph also depicts curtailed VRE,
mainly wind energy.
In Denmark, more than 90% of the curtailments comes
from responses to German surplus situations. In Ireland, curtailment
refers to the dispatch-down of wind for system-wide
reasons (where the reduction of any or all wind generators
would alleviate the problem) and not for localized network reasons.
When local network congestion is also considered, the
overall dispatch-down level in 2020 rises from 5.3% to 11.4%.
In Denmark, VRE exceeded demand for 845 h and reached
a high of 213% of demand in 2020. In the Denmark West
market area, shares greater than 100% were recorded during
2,117 h and greater than 350% during the most extreme
hour (3,637 MW of VRE and 1,041 MW of demand). System
operation without large power plants online has become
more frequent since the first event in 2015.
In South Australia, a new record of solar PVs, above 100%
of demand, was reached in October 2020 (Figure 2). Importantly,
the majority of the PV generation
(77%) was distributed, predominantly
residential PV systems.
This resulted in very low demand
on the transmission system, as the
majority of the underlying customer
consumption was supplied by the
distributed PVs. New records for the
minimum demand supplied through
the transmission system continue to
be broken-only 300 MW in October
compared with a peak demand
of around 3,100 MW. Current forecasts
for growth in distributed PVs
show the possibility of transmissionsupplied
demand falling below zero
for brief periods within the next one
to two years.
The Tasmanian power system is
220
200
180
160
140
120
100
80
60
40
20
a synchronous island, and it saw a
record-high system nonsynchronous
penetration (SNSP) of more than
90% in January 2021, based on a
mixture of high-voltage direct current
(HVdc) imports and local wind
generation on a system demand of
around 1,050 MW. The system has
november/december 2021
significant installed hydro capacity, with many units able to
operate in synchronous condenser mode.
In Ireland and Northern Ireland, a new record of 95%
of demand met by wind energy was achieved in January
2021. This high penetration has been facilitated by an
operational trial of 70% SNSP, which began on 15 January
2021. SNSP is the share of nonsynchronous generation
plus the net HVdc imports as a percentage of
demand plus net HVdc exports. The 70% SNSP level was
achieved on many occasions during the successful trial
(Figure 3). The two system operators, EirGrid and the
System Operator for Northern Ireland (SONI) are progressing
further, with a 75% SNSP trial that began on
22 April 2021.
In 2020 in Germany, VRE produced more than all
fossil generation (coal, oil, and gas) for the first time
(183 TWh compared to 178 TWh). Maximum instantaneous
VRE generation reached 74% on 5 July 2020,
and maximum instantaneous PV penetration was 56%
(37 GW) on 1 June 2020.
In the United States, Xcel Energy's operating company,
Public Service of Colorado, experienced an hourly
penetration of VRE of 83% and a monthly record 46%
of load in December 2020. In 2020, 36% of all customer
demand was served with VRE. This was primarily with
wind energy but excludes a growing amount of distributed
solar generation. The minimum net load was as low
as 438 MW in 2020.
10
2
4
6
8
Minimum Instantaneous Penetration Maximum Instantaneous Penetration
Average Annual Penetration
Curtailment
figure 1. The wind/PV penetration (excluding distributed energy resources) and curtailment.
The blue bars show the range of instantaneous shares of VRE in the grid-
the average share of demand is depicted with orange markers. In South Australia, the
maximum instantaneous penetration is from the grid demand, where the distributed
solar has reduced the demand that the transmission grid sees. The curtailed VRE, as
a percentage of the potential generation available, is shown with green dots. (The
scale is shown on the right y-axis.) ERCOT: Electric Reliability Council of Texas.
ieeepower & energy magazine
87
Wind/PV Penetration (%)
Potential Wind/PV Curtailed (%)
Brazil
Chile
Texas ERCOT
Germany
Colorado Xcel
Ireland Eirgrid
Denmark Energinet
South Australia

IEEE Power & Energy Magazine - November/December 2021

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