Presentation on theme: "Policy and Trade Mechanism of Distributed Generation on Smart grid Zhu, Shouzhen Wang, Xiaoyu Tsinghua University CIRED 2011."— Presentation transcript:
Policy and Trade Mechanism of Distributed Generation on Smart grid Zhu, Shouzhen Wang, Xiaoyu Tsinghua University CIRED 2011
2 Contents 1 Definition of Smart Grid 2 Characteristic of Smart Grid 3 The significance for interconnected with distributed generations to power system 4 Impact of Interconnecting Distributed Generation to Electric Network 5 The Pricing Policies and Trading Mechanism of Distributed Generation 6 Development
3 Previous Definition A self-healing and interactive grid with high level of digitalization and automation. Definition of “ Smart Grid ” by CSEE Current Version: A reliable and efficient grid which utilizes advanced information, communication and power technologies and equipments to systematically realize the intelligent monitoring, analysis and decision. The grid is self- healing and interactive. It has high automation level and supports renewable generation and flexible electricity consumption. 1 Defininition of Smart Grid
4 The system should be strong enough to support large capacity power transmission and utilization, can support big wind farm for whole system smooth operation. the system must be more robust to support reliable operation with some content flexibility. There are still some discussions on that. In order to satisfy the huge and fast increasing requirement of electricity demand in the whole country, the infrastructure construction of power industry in China is developed in a quite fast speed. Many new devices and technologies have been used for several decade years. After UHVAC demonstration transmission line is put into trial operation, the large scale renewable energy generation projects, such as wind power fields about 10giga-watt level, are planned and commenced to be built. The development of the smart grid is driven by the optimal control and management of the large power system along with environment protection and energy efficiency improvement which concerns power industry deeply. The capability of self-healing is considered mainly for distribution system. The technical guidelines for the smart substation and distribution are in the drawing procedure, and will be issued soon. The test and demonstration systems have already been arranged. The self-healing is one key issue for them. Strong and Smart Grid
5 Information Intense integration and exchange of real-time information Interaction Interaction among power generation, power grids, and end customers Automation automatic selection of control strategy self-healing in case of damages and contingencies 2 Characteristics of Strong & Smart Grid
6 Generation ： Integration of renewable generation, large scale of wind/PV/storage, distributed generation(DG) Transmission ： Ultra high voltage (AC/DC), transmission planning, FACTS ； intelligent equipments, long distance transmission, etc. Substation ： Substation automation, IED, condition-based maintenance, life- cycle management, etc. Distribution ： distribution planning, advanced distribution automation ， DG/microgrid, energy storage, etc. Operation and Control: EMS, electricity market, WAMS, advanced control center, etc. Information/communication ： Info.& comm. infrastructure, information modeling, cybertics, AMI, etc. Supply/Consumption ： marketing system, smart meter, demand response, etc. 2.1 Construction of Smart Grid
7 Smart Distribution To realize the functions such as the distribution network monitor and control, voltage / reactive power management, emergency management and self-healing control, security alarming after the distributed energy connection by the use of intelligent devices, intelligent terminals, intelligent master station system. Distribution automation Connection of the distributed generation Connection of the storage system Distribution
8 Development Focus Build a secure and reliable distribution network with power flow optimization, flexibility in reconstruction and accommodation of renewable energy; Unified control and compatible with centralized/decentralized storage devices and distributed energy Overall construction of practical distribution automation system Promote application results and technical equipments of smart distribution pilot projects Connection of the distributed generation Connection of the storage system Key Projects Optimization of distribution structure and distribution automation Research on intelligent distribution dispatching technology and its promotion Pilot project for the construction of EV charging station Pilot projects for the construction of large-capacity storage Distribution
9 3. The significance of distributed generation interconnection and the prime motors of DG system can be several kinds of energy switching facilities such as gas turbine, wind turbine, solar energy fuel cell,photovoltaic cell, waste incineration boiler, and so on. 3.1 Define of distributed generation (DG) In general, is an environmentally-friendly, energy saving power station installed at the loads. The capacity of DG can be from several kW to dozens MW,
10 (1) Economics (2) Environmental protection (3) Reliability (4) New direction of using new energy sources (5) Important content for power system development manner (6) Solution supply insufficiency in area of city center 3.2 As the important supplement of large electric power system 返
11 Beijing south Station Tianjin Station
DG interconnection Problem & development policy safety trade Technology rule DG DG interconnection 1 、 Macroscopical policies 2 、 Study the impacts of DG connection on power system 3 、 Established Technology and management of DG interconnection 4 、 Study Economic trade mode and electric rate policies between DG and electric grid
14 4 、 Impact of Interconnecting Distributed Generation to Electric Network 4.1 Impact of DG on stable voltage of distribution network 4.2 Impacts of DGs on power quality 4.3 Impacts of DG on power system in abnormal operating situation
15 Advantageous impacts on grid Improve power supply reliability of grid, especially the reliability of power supply for important user; Save cost of electric grid establish; Improve energy use efficiency and develop new-style energy source. Reduce environment pollution Peak shaving and reduce loss Dynamic voltage support
16 Disadvantageous impacts on grid Add to short circuit capacity of electric grid Add to difficulty of line voltage regulation Affect relaying protection Effect power quality
17 The studies of this report are focused on Study the impact of DG on stable voltage of distribution network, and discuss the reasonable locality and injecting capacity of DG units; study the power quality of distribution network with DG units, such as flicker, harmonics, unbalanced voltage and DC current injection and so on; Study the impact of DG in the abnormal situation, the contribution of DG to level of short circuit capacity and protection arrangement, and local stability of power system.
Impact of DG on stable voltage of distribution network
19 Feeder voltage and voltage change before and after DG connecting In the distribution network with DG, where rate of change is bigger is the top-priority locality of reactive-load compensation and voltage support.
20 DG locality change simulation Figure voltage contribution change with DG locality change Voltage distribution will have biggish differentia if DG units with the same output interconnected with different locality combination. Figure :voltage contribution with DGs concentrated at the sole node
21 General rule DG plays obvious active role in voltage support; If DG mounted position is selected at the position from which to the end total load equals to half of DG capacity, voltage of DG connecting point will be more stable ； In order to avoid situation that voltage of DG injecting point is higher than voltage of sending eng, it is necessary to restrict DG injecting capacity not beyond up limit; Interconnecting DG with large capacity to network will add to difficulty of substation voltage regulation. ； In normal situation, DG should generate more active power and less reactive power, and keep operating at high power actor.
Impacts of DG on power system in abnormal operating situation
23 Increase short circuit capacity and impact protection setting Impact of DG on fault current (1) Short circuit level of fault point is so large that short circuit current of feeder 1 in figure 3-17 exceeds capability of short circuit and broken circuit that switch gear (cable,short-circuiter and so on) in the feeder; (2) Generally, there is only overcurrent protection in 10kV feeder, without directivity. Therefore, when short circuit current of DG is too large, it will lead to protection b in figure misoperation and breaker 2 opening, which results in unnecessary supply interruption.
24 Increase short circuit capacity and impact protection setting Connecting DGs with inverter interface to power grid will not add to short circuit level of system; but connecting DGs with rotation interface will supply short-circuit current to increase fault current at short circuit point. To reduce and avoid disadvantageous impact of DG parallel to grid 1) limit parallel capacity of DG; 2) augment impedance of DG isolating transformer; 3) set directional power protection at the outlet of DG. Before connecting DG to grid, we must check generating equipment impedance to the full, and calculate short-circuit current addition due to DG parallel to grid, to determine interconnection capacity of DG. And for parallel DG with large capacity, it is necessary to set directional power protection.
25 Impacts on local stability Frequency response of 500kV corresponding to different DG penetration voltage response of 500kV corresponding to different DG penetration It is obvious that the case with DG and much higher system loads shows better dynamic response than the base case. The deviations of maximum voltage and frequency are less, and the oscillations show very slightly better damping.
26 5 、 The Pricing Policies and Trading Mechanism of Distributed Generation 5.1 Renewable Energy Based Distributed Generation (DG) 5.2 Cost-sharing Mechanisms of Renewable DG 5.3 Combined Cooling Heating and Power (CCHP) 5.4 The Model of Basic Price 5.5 Pricing Police and Trade of CCHP 5.6 Summary
5.1 The Pricing Policies and Trading Mechanism of Renewable-Energy-Based Distributed Generation (1) Mandatory policies Renewable Portfolio Standard (RPS) The green certificate market—renewable energy green certificate trading system (2) Economic incentive policies Feed-in Laws （ 3 ） Market development policies Tendering Policies
28 China Renewable Energy Law Applied in Jan. 1, No. 14 Renewable electrical will be sun purchaseed by electrical company. After Emended Applied in April 1,2010 No. 14 Renewable electrical will be indemnificatory sun purchaseed by electrical company.
Renewable Portfolio Standard (RPS) RPS includes the following rules: ① the amount or proportion of renewable energy electricity ② the deadline and duration of achieving given amount or proportion ③ the recognized amount or proportion of renewable energy electricity by generation, distribution, and transmission ④ the sorts of renewable energy and generation techniques ⑤ Certificates, Tracking and accounting method ⑥ the encouragement to the suppliers who achieve RPS and Enforcement penalties who not ⑦ the cost limit of generation and trade of renewable energy RPS can effectively spur renewable development and encourage competition among renewable energy producers.
The green certificate market—renewable energy green certificate trading system charge Green card Renewable electricity producers Administrator and report forms Quota obliged customers registratio n Quota monitor Quota obliged electricity customers Green card charge Transaction info. data Data Green card transction market Figure Green card and its procedures
5.2 Cost-sharing Mechanisms of Renewable DG Economic incentive policies all sorts of incentive policies cash subsidies, preferential pricing policies, reductions of tax revenue, loans at low interest rates or loans with interest allowance. Feed-in Laws:A feed-in law is a price-based policy that specifies the price to be paid for renewable energy.
32 China Renewable Energy Law Applied in Jan. 1, Price management and cost-sharing No. 19 The tariff of renewable generation is decided by the government according to type, development level, and area of renewable generation 。 The tariff should be publicized. No. 21 The expenses for the utilities to buy renewable generation can be included into the generation cost and reimbursed from the retail sales of electricity.
Cost-sharing Mechanisms of Renewable DG Establishing Renewable Fund Analysis of the sales price of electricity The sales price of electricity including 4 parts: purchasing cost, transmission-distribution loss, transmission- distribution tariff, and government fund. Design of cost-sharing Renewable Energy Fund = Cost-sharing level If shared in the whole country, the level of cost- sharing is only 0.95 RMB/MWh.
34 Green power marketing The principles for design Decision of tariff to voluntarily purchasing GE=RE-CE-EC fees of decontamination for coal electricity EC=0.6× (sum of quantities of equivalent of top 3 main pollution)=0.010 ￥ /kWh, so GE=0.244 ￥ /kWh.
35 Trading mechanism based on green power marketing Electric Power Company as the main marketing unit Green certificate market
Suggestions on price policy of distributed renewable energy generation The total amount of renewable energy production and consumption should be regulated.; The nation supports to establish green electric power system ; The nation encourages and supports interconnection and generation of the multiform renewable energy ; The State adopts a categorized electricity price for the power purchase price of the renewable energy electricity.
Combined Cooling Heating and Power (CCHP) Background CCHP is a small or micro integrated energy supply system installed around the user. Compensatory expenses for the reserve capacity When CCHP needs spare sustainable capability from the grid while operating, it should compensate power utilities for the reserve capacity.
The Model of Basic Price Long term Marginal Cost methodology for pricing Marginal capacity cost Marginal generation capacity cost Marginal transmission & distribution capacity cost yearly payback investment
Pricing Police and Trade of CCHP Determination of compensatory expenses Compensatory expenses (RMB/month) = Basic price (RMB /kW·month) × reserve capacity (kW) Marginal generation capacity cost
41 Marginal transmission & distribution capacity Basic price
42 Collect governmental fund from CCHP The quantum of public utility add-ons (three-gorge fund, rural grid loan fund) is: 4 cents per kWh, for lighting and commerce. The related fees of interconnection Trade mechanism of CCHP
Relation between the price of natural gas with cost of cost of CCHP system Figure The fluctuation of natural gas price affect CCHP generation cost Figure Effect of natural gas to annual economic benefits
Policy Suggestions for the Development of (CCHP) Set up the interconnection rules Promoting CCHP consultant industry, and encouraging ESCO and public utility to take part in the investment, construction and management of CCHP The related fees of interconnection The state levies governmental fund to Distributed Generation; The quantum of public utility add-ons (sanxia fund, rural grid loan fund) is: 4 cents per kWh, for lighting and commerce. Charge compensatory expenses of the gird- interconnected Distributed Generation; the compensated expenses standard of spare sustainable capability refers to Basic price: RMB/KVAmonth(Beijing), RMB/KVAmonth(Anhui)
Table Trade model of distributed CCHP of Shanghai Serial numberTrade modelremark Shanghai Pudong Airport The power supply side undertakes the cost of combining to the grid and increasing the capability; take charge of standby capability cost in public grid: 27 RMB/kW/month In commission (interconnectio n), general no anti-inject Shanghai Minghang Hospital The power supply side undertakes the cost of combining to the grid and increasing the capability; the power company charge cost for equipment of public grid leave unused; discharge the inject cost; In many ways financing: Shanghai power company, China National Petroleum Corporation, Gas Corporation of Shanghai and some design companies Operate and interconnect, no anti-inject Shanghai Shuya Liangzi Healthy Recreational Center The power supply side undertakes the cost of combining to the grid and increasing the capability In commission (no interconnect) Shanghai Bao Steel (self-supply generation plant) The power supply side undertakes the cost of combining to the grid and increasing the capability; Shanghai power company charge Bao steel 0.13 RMB per unit for serving; the tax of station or region is handed in by Bao steel. In commission
Summary -1 For renewable energy, the paper brings forward two reasonable methods of cost- sharing to allocate the cost differential between renewable energy and conventional energy. Cost-sharing level of Renewable Energy Fund is estimated based on the analysis of electricity sales price and sharing principles. Volunteering Purchasing Mechanism of green power marketing is established. All above methods give some suggestions of associate measures to Renewable Law.
Summary -2 For CCHP, the paper brings the proposal of compensatory expenses to the reserve capacity of power system while interconnection. The basic price tariff and expenses standard of different voltage levels is calculated by using Long Term Marginal Cost methodology. It also brings forward the suggestions of governmental fund and related fees. A trading mechanism for CCHP interconnection is given in the final.
48 Distributed Generation is a new direction in the development of energy resources in future. Interconnection with the grid is a key step in its progress. Recognition Impact of DG to power system Distributed Generation must have relevant technology qualifications of interconnection. It should accord with the capacity and voltage level of interconnection, suffice power quality and the conditions of connection and disconnection. 6 Development
49 MicroGrid There are two design modes for Distributed Generations. One is that a generator or some supply electric power to a special user, and they are isolated from the power grids in electric and become a small system,call MicroGrid.
51 Distributed CCHP can effectively control or cut down the supply demands in heating and cooling, vacate much load capacity and optimize the load structure 。 CCHP —— a newest energy integrated optimizing scheme CCHP laboratory in Tsinghua University