Renewable Energy Generation: Challenges and Practices. CHEN Guoping State Grid Corporation of China (SGCC) Sep 7, 2018

Transcription

1 Renewable Energy Generation: Challenges and Practices CHEN Guoping State Grid Corporation of China (SGCC) Sep 7, 2018

2 Contents 1. Developments of Renewable Energy in SGCC 2. Challenges on Large-scale Wind and Solar Power Integration 3. Work carried out and proposed by SGCC 2

3 Introduction of SGCC SGCC is the world s largest public utility company which serves over 1.1 billion people and covers 88 % of the Chinese territory. By July 2018, the total generating capacity installed in SGCC s service area had reached 1427 GW. The maximum load in SGCC s service area reached a historical high at 810 GW on July 25, Generating capacity by energy source (July 2018) Nuclear 23GW, 1.6% ( 10.1%) Coal 799GW, 56.9% ( 3.6%) GW Load curve on July 25, 2018 Solar 142GW, 10.1% ( 41.9%) Gas 60GW, 4.2% ( 7.7%) Wind 137GW, 9.8% ( 11.5%) Hydro 225GW, 16.0% ( 2.0%) Other thermal 42GW, 3.0% ( 10.5%) :00 4:00 8:00 12:00 16:00 20:00 24:00 3

4 Promoting UHV Power Transmission China s coal, wind and solar energy resources concentrate in the Three-North areas, while hydro power resources are mainly located in the southwest. However, over 70% of electrical load resides in Central and East China. SGCC actively promotes the ultra-high voltage (UHV) power transmission to facilitate large-scale, long-distance allocation of energy resources. It has constructed 11 UHV DC projects with a total length of over 40,000 km, and the interregional transmission capability exceeds 96 GW. The ongoing Changji-Guquan project is the world's state-ofthe-art UHV DC project with the highest voltage (±1100 kv), the largest capacity (12 GW) and the longest transmission distance (3324km). HVDC UHVDC Northwest Southwest hydro power base Northwest coal, wind & solar power base Southwest To South China From Russia North and Northeast coal and wind power bases North Central East Northeast Load center 4

5 Renewable Power Generation In 2011~2017, the average annual growth of hydro, wind and solar power generating capacity were 6%, 24% and 93%, respectively. By July 2018, SGCC has 504 GW of renewable power generation installed in its service area (225 GW hydro, 137 GW wind, 142 GW solar with 39 GW distributed PV). GW Renewable power generation in SGCC Hydro/ 水电 Wind/ 风电 Solar/ 光伏 Wind & solar power in provincial grids 新疆 西藏 0~20 20~50 50~ ~200 >200 Unit: GW 青海 黑龙江 蒙东吉林辽宁蒙西冀北北京冀南天津宁夏山西山东甘肃陕西河南江苏安徽四川重庆湖北上海浙江湖南江西贵州福建云南台广西广东湾 海南 5

6 Wind & Solar Energy Consumption In 2011~2017, the average annual growth of wind and solar energy consumption were 26% and 134%, respectively. In 2018, wind and solar energy accounted for 8.4% of the total electricity generation in SGCC by August; the growth rate of wind and solar energy consumption (38.4%) was much higher than that of total electricity consumption. GWh 250 Renewable energy generation in SGCC Wind/ 风电 Solar/ 光伏 6

7 Contents 1. Developments of Renewable Energy in SGCC 2. Challenges on Large-scale Wind and Solar Power Integration 3. Work carried out and proposed by SGCC 7

8 Difficulties on Load Following The volatility of wind power output results in difficulties on load following. In 2017, the total wind power output in SGCC varied from 63 to 7.9 GW, and the maximum intraday variation reached 32 GW. China heavily relies on coal power with limited regulation capability, while flexible power sources contributes a very small portion. The grid regulation capability further reduces during heating period. Load and wind power in Northwest China, March In March 2018, the wind power output in Northwest China grid varied from 2 to 31 GW, and the maximum intraday variation reached GW. Load (GW) 50 0:00 4:00 8:00 12:00 16:00 20:00 0 Wind (GW) 8

9 Challenges from Power Electronics Wind and solar power generation is integrated into the system via power electronic components, which lacks active/reactive power regulation abilities. As conventional generators are replaced by wind and solar power, the system presents weaker inertia, damping and robustness to grid disturbances. This is a large challenge to the security and stability of the system. Grid in the past Present and future grid Inertia from conventional generators 100% conventional Conventional<70% Wind & solar>30% The evolution of power system in China Inertia from conventional generators Lost inertia 9

10 Intolerance to Grid Disturbances Wind and solar power generation lacks tolerance to grid disturbances such as high frequency and high/low voltage. It may be off the grid after a grid fault and worsen the situation. In January 2014, the transient overvoltage (128%Un) caused by a Tianshan-Zhongzhou UHVDC fault resulted in the loss of 25 wind turbines by overvoltage protection in Qiaowan wind farm which is 400km away from Tianshan station. Overvoltage caused by Tianshan-Zhongzhou UHVDC fault (PMU recordings) Comparison of tolerance levels of wind turbines and coal-fired generators 128%Un Wind Coal-fired Overvoltage 1.1 p.u. 1.3 p.u. Overfrequency 50.2Hz 51.5Hz Primary frequency response None 6% Power factor 0.95 leading ~0.95 lagging 0.95 leading ~0.85 lagging 10

11 Grid Oscillation Problems Multi-form sub/super-synchronous oscillations (SSOs) are likely to occur in a weak grid with high wind power penetration. Since 2015, more than 100 SSOs have happened near Tianshan-Zhongzhou UHVDC converter stations and wind farms in Hami, Xinjiang. 照阳河 牧场 鹿原 长青 至汗海 白龙山 博丰 华锦 东山 乌登山 国华佳鑫永发东湾 宏达 麒麟山金阳义缘站坝头 风电场 500kV 变电站 200kV 变电站 固定串补 500kV 线路 200kV 线路 九龙泉 沽源 察北站 中宝 莲花滩 至太平 桦树岭 恒泰 秋林 冰峰 韩家庄 Wind power oscillations in Guyuan, Hebei SSOs triggered by wind power in Hami, Xinjiang 11

12 Contents 1. Developments of Renewable Energy in SGCC 2. Challenges on Large-scale Wind and Solar Power Integration 3. Work carried out and proposed by SGCC 12

13 Analyzing Grid Characteristics SGCC performs researches and innovations on basic theory, grid control and simulations, which improves the recognition of grid characteristics. Construct the world s largest hybrid analog/digital real-time power system simulation platform and the first 900-Tflops supercomputing platform designated for power system simulation. Conduct hybrid electro-mechanical/electro-magnetic transient simulations to accommodate the trend of power-electronization of power systems. Supercomputer center Verification of UHV DC simulation models 13

14 Enhancing and Utilizing Transmission Continuously strengthen the grid to improve long-distance power transmission capability. Establish market mechanisms to reduce the number of online fossil-fuel power units and give full play to their regulation capabilities. Closely monitor and effectively utilize the grid regulation capabilities and the available transmission capacity of tie-lines to consume renewable energy to the maximum extent. Prospective interregional grid in 2030 Real-time grid balance monitoring 14

15 Improving Regulation Capability Support the upgrade of coal-fired generators to allow lower minimum load levels for wider ranges of power output adjustments. Promote grid-scale energy storage and expedite the construction of pumped-hydro plants. Over 24 GW of pumped hydro is expected to be in service by Establish power balancing mechanism with distributed energy storage and demand response, and make room for renewable energy through markets of generation rights and ancillary services. 100% 80% Load/Generation Wind + solar Load with demand-side 60% management 40% 20% 0% China/ 中国 Denmark/ 丹麦 Germany/ 德国 Load without demandside management Time Minimum load level of coal-fired generators Power balance affected by demand-side management 15

16 Promoting Grid-friendly Wind & Solar Power Revise the grid code compliance to include high/low voltage ride-through (LVRT/HVRT) requirements for wind turbines, and construct testbeds to support the upgrade of wind turbines for LVRT/HVRT capabilities. Conduct researches on primary frequency response (PFR) capability of wind turbines and wind farms, and carry out experiments in Northwest China grid. Promote virtual synchronous generator (VSG) control of wind turbines and PV units to enable grid-friendly capabilities including inertia, damping, PFR and reactive voltage regulation. Frequency Pper 130%Un_500ms 125%Un_1s 120%Un_10s 115%Un_10s 110%Un_ Hz kw Fref Pact Pref s Hz MW 定子电流闭环及调制 P Q 功率计算 VSG 本体模型 无功调节 Q R kq Qref 1/Ls - - u abc Eref E0 Uac + Uac_ref sin E abc AVR sin( 2 / 3) sin( 2 / 3) 0 + 1/s + P - 1/Js - D 有功调节 ω kf Pprim Pm Pmppt PI ωref Pref Umppt Udc ua ub uc s Revised requirements on LVRT/HVRT of wind turbines PFR test on wind turbines and wind farms VSG control of PV inverters 16

17 Conclusion and Outlook By 2030, wind and solar power in SGCC is expected to make up 30% of generating capacity and 16% of electricity generation; the proportion will further rise to 50% and 30% by SGCC will dedicate to a next generation power system with better connectivity, intelligence, flexibility and safety, and actively promote the development of renewable power to support China s transformation towards clean and low carbon economy. Generating capacity 2015~2050 Electricity generation 2015~ % 60% 11% 21% 30% 37% 40% 52% 20% 60% 54% 39% 33% 17% 0% % 60% 4% 9% 16% 20% 40% 34% 20% 66% 64% 54% 47% 29% 0% Fossil fuel/ 火电 Wind + solar/ 新能源 Fossil fuel/ 火电 Wind + solar/ 新能源 17

18 Thank you for attention! 18