某种程度上，不可预测Two key assumptions in previous analysis

Valuation and Integration of Solar Energy: 太阳能评价与并网 Early Results from the United States 美国初期研究成果 Ryan Wiser 怀瑞恩 Consultant to the Center for Resource Solutions 资源解答中心专家 Energy Foundation Workshop 能源基金会研讨会 Beijing, China July 2, 1010

Motivation 研究动机 Increasing focus on solar as source of electricity: -

Growth in interest in large-scale plants: >50 GW seeking interconnection in U.S., ~10 GW in later stages of development

太阳能发电受到越来越多的关注 -

美国对大规模电站的兴趣在提升： 预期的并网需求超过50GW，约 10GW的项目处于开发的后期阶段

Decision-makers need to understand electric 决策者需要认识到太阳能电力在电 system value of solar electricity (PV/CSP, w/ 力系统中的价值（光伏/光热，有无 and w/o storage): 储能） -

Solar is variable/unpredictable: valuation will differ from conventional gen.

太阳能具有波动性/不可预测性：其 评价方法将有别于常规能源

-

Output variability/uncertainty studied for wind; little similar work on solar

针对风电出力变化/不确定性已有研 究；太阳能这方面的研究却很少

Two areas of particular interest:

-

两个主要研究方向：

-

Estimating the long-term electric system value of solar without storage given displacement in conventional gen. and optimal capacity expansion

-

Understanding the technical and economic impacts of short-term variability and uncertainty in PV output, and associated integration costs

Current presentation does not include power quality timeframe

-

估算无储能太阳能在电力系统中替 代常规电力的长期价值，及最佳容 量 了解光伏发电输出短期波动性和不 确定性带来的技术和经济影响及并 网成本

目前的报告并不包括瞬时电能质量 2

Long Term Valuation 长期价值

3

Value of an Electricity Generation Source Impacted By Multiple Factors

电源价值受多种因素影响

发电成本

输电成本

并网成本 容量价值 能源价值

4

Central Solar in Western U.S. Currently >3 cents/kWh More Valuable Than Wind Considering Energy/Capacity Value 考虑到能量/容量价值，美国西部集中式太阳能价值比风电高3美分/度 $140.00

Capacity Value Energy Value Transmission Cost

Economic Value ($/MWh)

$120.00 $100.00 $80.00 $60.00 $40.00 $20.00 $0.00 Solar

Load Sited CCGT Hydro

Biomass

Geothermal

Wind

-$20.00 -$40.00

Increased value due to coincidence with system peak, and therefore offset of higher-cost resources; benefits likely to be lower in China 因与用电负荷高峰重合而增加了太阳能电力的价值，所以抵消了部分高成本；在中 国，这方面的价值可能要低一些

5

Marginal Value of Solar Energy Drops with Penetration, But At Current Levels, Added Value Is Considerable 随着在总体电源中比重的增加，太阳能的边际价值会减少，但在目前的水 平下，增值仍相当可观 49

Load (GW)

120 Solar reduces peak load (high capacity value)

100

45 Load Net Load, 1% Solar Net Load, 2% Solar Net Load, 3% Solar Net Load, 4% Solar

43 39 35 9 AM

80

2 PM

7PM

12 AM

5AM

Local Time Beginning 9/8/2004

60 Solar shifts peak load into night hours (low/no capacity value)

40%

35%

30%

25%

20%

Solar increasingly curtailed during peak production

10%

5.0%

4.0%

3.5%

3.0%

2.5%

2.0%

1.5%

-

1.0%

Wind: Long-Run Equib., no Storage Solar: Long-Run Equib., w/ Storage - 10% peak, 168h Solar: Long-Run Equib., no Storage Solar: 80% Incumbent, no Storage

20

15%

40

-

Marginal Value of Renewable ($/MWh)

140

Renewable basis) RenewablePenetration Penetration(% (%energy energy basis) 可再生能源比重（发电量）

6

Incremental Wind or Total Analyzed (GW)

For PV (less so for CSP), Lower Transmission Needs Further Augment Added Market Value 对于光伏（光热的情况不太 一样），较低的输电需求进 一步增加了它的市场附加值 Figure shows estimated transmission cost for wind in US for large number of studies: > 1 cent/kWh 基于大量研究，数据表明美国风 电的输电成本高于1美分/度电 Solar PV is modular and does not experience as strong economies of scale, allowing siting closer to load in many cases 太阳能光伏是由一个个独立模板 组成的，规模经济效益不如其他 电源明显，并且很多情况下可以 建在负荷周边

0

5

10

15

20

PSCo NYISO MISO '03 - 1 MISO '03 - 2 Xcel - BRIGO ISO-NE - Low SCE - ISM - MP ERCOT - C3 CapX - CBED IAP - 2010T SPP - 1 SPP - X RMATS - 1 CDEAC SCE - ISM - K ERCOT - Cb3 SPP-CRA MATL Xcel - BR - Proj JCSP SSG - WI SCE - ISM - V SWAT CapX - 1 CPUC - 2017 ERCOT - M2 SCE - ISM - P CapX - 2 CPUC - 2010 IAP - 2020 SPP - 2 ERCOT - CW3 ERCOT - Cb1 Xcel - BR - Actual CAISO - A1 ERCOT - Cb2 SCE - ISM - I SCE - IR ERCOT - TOS - 4 ERCOT - P4 SCE- LA/Kern SPP - EHV ERCOT - TOS - 3 RMATS - 2 SCE - ISM - EDM CLRTPG - N1 SPP - OK - 2020H Tehachapi ERCOT - TOS - 2 EPTP - 1 SPP - OK - 2020N MSTI NTAC - 2A' CAISO - A2 SunZia CAISO - A6 SPP - OK - 2010H ERCOT - TOS - 1A ISO-NE - High SPP - OK - 2010N EPTP - 2 NorthWestern ERCOT - TOS - 1B MPC TWE and GS NTAC - 2A NTAC - 2B Frontier - B Frontier - A CAISO - A4 HPX C/PNW-NorCal NTAC - 1

25

30

Unit Cost (Capacity-weighted) Wind Analyzed (GW) Total Analyzed (GW)

236 GW wind analyzed

$0

$500

$1,000

$1,500

$2,000

Unit Cost of Transmission ($/kW-wind) $0

$24

$49 Unit Cost of Transmission ($/MWh-wind)

$73

7

$98

But, Solar without Storage Is Also Variable and, to a Degree, Unpredictable 但是，无储能太阳能仍然是波动性较大的，某种程度上，不可预测 Two key assumptions in previous analysis - Perfect foresight (did not evaluate forecast error)

之前分析的两个关键假设 - 完美预测（预测误差未评估） - 不存在小时内波动 (需要平衡小 时内波动)

- No sub-hourly variability (changes within hour require balancing)

Costs for dealing with imperfect forecasts 预测误差带来的成本/ 小时内波 动= “并网成本” / sub-hourly variability = “integration - 大量研究表明，风电并网成本 < costs” - Wind integration well studied: cost < $10/MWh

$10/MWh （10美元/千度电） - 但对太阳能并网成本认知还太少

- Integration costs for solar poorly understood

Note: Focus here is on large-scale PV; CSP with and without storage a much smaller concern due to thermal inertia and storage

注意: 此处关注的是大规模光伏; 有 储能或无储能的光热因其热惯量和 储存问题，受关注更少 8

Short Term Integration 短期并网

9

Clouds Can Produce Rapid Ramps in PV Output 阴云会导致光伏出力锐减 PV plant output can change by 70% in five minutes at single site 一个光伏电站的发电出力，在五分钟内变化可达70% Clear Day (May 1)

Cloudy Day (May 3) 100%

80%

80%

Solar Output (% Maximum Output)

Solar Output (% Maximum Output)

100%

60%

60%

40%

40%

20%

0% 7:00

20%

9:00

11:00

13:00

15:00

17:00

19:00

0% 7:00

9:00

11:00

13:00

15:00

17:00

19:00

Timeplant (hh:mm)output on a clear and cloudy Actual PV day for a Time (hh:mm) plant in the Southwest United States

10

Operational Impacts Vary with Time Scale 针对不同时段运行影响有所不同 Regulation: Automatic adjustments to conventional generation output to maintain balance between supply and demand 调节：自动调整至常规发电 输出保持供需平衡 Load Following: Periodic operator dispatch of generation to follow trends in load 负荷跟踪：分时段运行调度 以配合负荷变化趋势 Scheduling: Commitment of generation units based on forecasted need for generation 调度计划：基于需求预测的 发电约定

Source: Milligan 2009

Concerns that Rapid Fluctuations in Output Are a Potential Roadblock to PV 对光伏出力快速波动的担忧有可能阻碍光伏的发展  Market operators / utilities have expressed concern  市场运营商/电力公司表示这样的担忧  Numerous early studies found potential limits to increased PV penetration

 大量早期研究给出了光伏电源整体占比的可 能极限  But… many of early concerns did not account for geographic diversity and forecasting  然而 …许多的担忧并未基于全面考虑，分 散的地理分布因素和预测贡献的因素都未考 虑  Solar PV’s characteristics allow for ready use of site diversity and forecasting  太阳能光伏的特征允许分散式布局和利用预 测技术

12

Solar Plants Are Variable, But Output Smoothing from Geographic Diversity

太阳能电站有波动性，但分散的地理分布可以平滑这种出力波动 

Clouds cause rapid changes in output of individual plants



就单个电站而言，阴云会引发快速的出力波动



Multi-MW plants can change by > 70% in less than 5-min



兆瓦级电站在五分钟内变化可达70%以上





Aggregation dramatically reduces variability; even within-plant variability at < 1 min reduced with plant size due to smoothing 将众多电站作为整体考虑，则波动会大幅降低；同理，即便是单个电站范围内，一分钟内波动也 随电站规模扩大而减少

Source: Wiemken 2001 Actual 5-min data from 100 PV plants in Germany. Aggregate output (P) is normalized by installed capacity (P installed) 13

Aggregation Decreases Relative Variability When Sites Are Less Than Perfectly Correlated 整体优势在电站分布不是非常集中的情况下可以降低相对波动性 Deltas: step changes from one averaging interval to the next Clear Sky Index: ratio of insulation if no clouds were present to measured insolation Data: 1-min insolation data from 23 timesynchronized sites in the U.S. Source: Mills and Wiser 2009

Forecasting for Solar Still Developing, But Is Much Better for Geographically Diverse Sites 太阳能预测技术仍在发展，针对地理上分散分布的电站来讲预测效果更佳 Clouds lead to forecast errors, and errors are greatest on partly cloudy days Forecast errors for geographically diverse sites smoothed by aggregation 阴云导致预测偏差，多云/晴转阴的天气会加大误差。不同地区多电站形成的整体优势可以降低预测误差。

Source: Lorenz 2009

Forecasts of solar output based on forecasts from the European Centre for Medium-Range Weather Forecasts 15

Longer Forecast Horizon Increases Error 远期预测误差增大 Assuming that current cloud conditions will not change (persistence forecast) is reasonable for short forecast horizons (