KEYWORDS energy efficiency, energy consumption, renewable energy, high voltage substations

Transcription

1 /11/ kv Gura Ialomitei - Environmentally friendly High Voltage substation Ciprian. G. DIACONU Mihai C. MARCOLT National Power Grid Company TRANSELECTRICA SA Romania ABSTRACT In this paper we present a detailed analysis of the possibility to modify old high voltage substations into more energy efficient and more environmentally friendly ones. In the core of the paper we apply these ideas to the /11 Gura Ialomitei high voltage substation for the sustainable development of the Smart Grids concept. We will turn a classical high voltage substation into an environmentally friendly and more energy efficient one simply by rationalizing energy consumption and by providing a larger percentage of the electricity needed from renewable energy sources. This idea is applicable more effectively to refurbished substations that are switching from AIS to GIS technology. In these substations the empty space left behind after the refurbishment can be used to produce electricity through the installation of mini wind turbines and photovoltaic panels. The electricity producing system will consist of: photovoltaic panels and mini wind turbines, batteries that will store the electricity produced, inverters that will turn DC power into AC power and the automations required. This system will supply the electricity needed for the small consumers and also for the vital ones like internal services of the high voltage substation and the driving mechanisms of the switching gear. Of course, the system will still be redundant, capable of supplying consumers with electricity from the distribution network, from the diesel generator or, for some of the consumers, from the transformer s tertiary. The first action taken was to reduce energy consumption in the substation by several methods, like: - replacing conventional light bulbs with LED technology light bulbs; - the use of heating pumps for cooling or heating the substations buildings; - proper thermal insulation of the buildings, etc. The paper includes in the final part a detailed analysis for the operating modes of the new system integrated in the high voltage substation. These choices were made by analysing different scenarios developed from a technical point of view and also from an economical point of view throughout the lifetime of the substation. KEYWORDS energy efficiency, energy consumption, renewable energy, high voltage substations 1. INTRODUCTION The paper will reveal all the data following the next step by step schedule: - Identification of the consumers in the /11/ kv Gura Ialomitei substation; - Methods of reducing the energy consumption; - Energy consumption analysis for two extremes: hot summer day and cold winter day ; - Energy consumption after applying the reduction methods; - Defining the surfaces that can be used for installing the wind turbines and photovoltaic panels after the refurbishing of the high voltage substation (from AIS to GIS technology); - Choosing the renewable energy mix depending on the wind speed and solar radiation in the geographical area; - Technical and economic analysis. 2. IDENTIFICATION OF THE CONSUMERS IN THE GURA IALOMITEI SUBSTATION DC consumers /11/ kv Gura Ialomitei substation DC consumer Consumption (kw) of consumers Total consumption (kw) 1 DC kv consumers DC 11 and kv consumers ACOS relays Safety lighting Total DC power consumption (kw) 14.5 Table 1. DC consumers

2 AC Consumers /11/ kv Gura Ialomitei substation Consumption (kw) of consumers Total consumption (kw) 1 Cooling batteries for Trafo 25 MVA /11 kv Cooling batteries for Trafo 16 MVA 11/ kv Fire detection and extinguishing systems Sergi Drive switches for kv Circuit breakers Drive switches for 11 kv Circuit breakers Drive switches for kv Dissconectors Drive switches for 11 kv Dissconectors Fluorescent lamp lighting for buildings Incandescent lamp lighting for buildings Perimeter lighting Exterior lighting Air conditioning systems Axial fans Central heating boiler 1 15 Electric heating Boiler Submersible pumps Electro pumps Other consumers relay protection containers Section 1 and 2 for kv Household consumers (fridge, microwave, TV etc) Workstations (PCs) metering, protection, management, etc Personnel PC workstations Video surveillance, intrusion detection, alarm, etc Total AC power consumption (kw) Table 2. s 3. ENERGY CONSUMPTION ANALYSIS FOR TWO EXTREME SCENARIOS: HOT SUMMER DAY AND COLD WINTER DAY 1 st scenario Hot summer day As we described in the last chapter, the consumers and the power consumption are the ones stated in Table 1 and Table 2. In a hot summer day consumption scenario we analysed the consumers during the 24 hours interval. The results will be shown in Table 3 and Diagram Cooling batteries for Trafo 25 MVA /11 kv Cooling batteries for Trafo 16 MVA 11/ kv Fire detection and extinguishing systems Sergi 4 Drive switches for kv Circuit breakers Drive switches for 11 kv Circuit breakers Drive switches for kv Dissconectors Drive switches for 11 kv Dissconectors Fluorescent lamp lighting for buildings Incandescent lamp lighting for buildings Perimeter lighting Exterior lighting

3 Power consumption (kw) 12 Air conditioning systems Axial fans Central heating boiler 15 Electric heating 16 Boiler Submersible pumps Electro pumps Other consumers relay protection containers Section 1 and 2 for kv Household consumers (fridge, microwave, TV, etc.) Workstations (PCs) metering, protection, management, etc Personnel PC workstations Video surveillance, intrusion detection, alarm, etc. Total power consumption (kw) Table 3. Energy consumption of the substation during a hot summer day 1 Energy consumption in a hot summer day Time interval (h) Diagram 1. Energy consumption of the substation during a hot summer day 2 nd scenario Cold winter day As we described in the last chapters, the consumers and the energy consumption are the ones stated in Table 1 and Table 2. In a cold winter day consumption scenario we analysed the consumers during the 24 hours interval. The results will be shown in Table 4 and Diagram Cooling batteries for Trafo 25 MVA /11 kv Cooling batteries for Trafo 16 MVA 11/ kv Fire detection and extinguishing

4 Power consumption (kw) systems Sergi 4 Drive switches for kv Circuit breakers Drive switches for 11 kv Circuit breakers Drive switches for kv Dissconectors Drive switches for 11 kv Dissconectors Fluorescent lamp lighting for buildings Incandescent lamp lighting for buildings Perimeter lighting Exterior lighting Air conditioning systems 13 Axial fans Central heating boiler Electric heating Boiler Submersible pumps Electro pumps Other consumers relay protection containers Section 1 and 2 for kv Household consumers (fridge, microwave, TV, etc.) Workstations (PCs) metering, protection, management, etc Personnel PC workstations Video surveillance, intrusion detection, alarm, etc. Total power consumption (kw) Table 4. Energy consumption of the substation during a cold winter day 1 Energy consumption in a cold winter day Time interval (h) Diagram 2. Energy consumption of the substation during a hot summer day

5 In the initial substation consumers configuration the energy consumption in the two scenarios analysed is: - Hot summer day = 712,1 kwh/day; - Cold winter day = 751,36 kwh/day. 4. METHODS OF REDUCING THE ENERGY CONSUMPTION Using heat pumps as climatisation method; Replacing classic lighting with LED lighting; Thermal rehabilitation of the buildings located in the substation. In a few words energy efficiency. Heat pumps Improving energy efficiency of industrial and civil processes is done by introducing in energy flow the secondary energy resources that occur and grow simultaneously with these processes. Heat pumps are part of these installations which can bring a significant contribution to a better use of energy for heat supply to a moderate heat levels, required by many processes and especially for heating and hot water consumption of industrial buildings. The heating, cooling and hot water system at Gura Ialomitei /11/ kv station is composed in current situation by: ten Split air conditioning systems, two axial fans, one gas boiler, ten electrical heaters, one water heater, four submersible pumps and two electrical pumps. The installed power of these devices is 91.8 kw per total and it varies depending on season, time of heating/cooling, day/night. For improving the energy efficiency on the Gura Ialomitei station by modifying the heating system, we replaced the air conditioning systems, axial fans, electrical heaters and the water heater with two airwater mono-block pumps (15 kw) near the buildings and eight air-water mono-block pumps on the roofs (4 kw). The investment in air-water pumps is presented in the table below: Pump Installed power Price [euro] Total Price [euro] REHAU AERO 15 kw VIESSMANN 4 kw 5 TOTAL 59 Table 5. Heat pumps used and total investment costs Amortization of the heat pumps will be made in approximately 6 years. LEDs By replacing fluorescent and incandescent lamp lighting with LED lamp lighting the energy consumption will decrease by 8%. In the tables below we will detail the LEDs that we will use and total investment for this. LEDs description Pieces LED 15 W - interior 9 LED projector 3 W - perimeter 3 LED projector 15 W with movement sensors - exterior LED projector 2 W with movement sensors and PV panel - exterior 1 LED projector 21 W with movement sensors - exterior 45 LED projector 3 W - exterior 55 Table 6. LEDs used TOTAL investment for LEDs (Euro) 28,35 Table 7. Investment costs for LEDs Amortization of the LEDs will be made in approximately 1 years. Thermal rehabilitation of the buildings was made during the investment of rehabilitation of the substation.

6 5. ENERGY CONSUMPTION AFTER APPLYING THE ENERGY SAVING METHODS Power consumption evolution after applying the saving methods. AC Consumers /11/ kv Gura Ialomitei substation Consumption (kw) of consumers Total consumption (kw) 1 Cooling batteries for Trafo 25 MVA /11 kv Cooling batteries for Trafo 16 MVA 11/ kv Fire detection and extinguishing systems Sergi Drive switches for kv Circuit breakers Drive switches for 11 kv Circuit breakers Drive switches for kv Dissconectors Drive switches for 11 kv Dissconectors LED lamp lighting for buildings LED lamp lighting for buildings Perimeter lighting Exterior lighting Air conditioning systems Axial fans Central heating boiler 1 15 Electric heating Boiler Submersible pumps Electro pumps Other consumers relay protection containers Section 1 and 2 for kv Household consumers (fridge, microwave,tv etc) Workstations (PCs) metering, protection, management, etc Personnel PC workstations Video surveillance, intrusion detection, alarm, etc Total AC power consumption after applying the saving methods (kw) Table 8. AC Consumption after applying the saving methods In a hot summer day consumption scenario we analysed the consumers during the 24 hours interval after applying the energy saving methods. The results will be shown in Table 9 and Diagram Cooling batteries for Trafo 25 MVA /11 kv Cooling batteries for Trafo 16 MVA 11/ kv Fire detection and extinguishing systems Sergi 4 Drive switches for kv Circuit breakers 5 Drive switches for 11 kv Circuit breakers 6 Drive switches for kv Dissconectors 7 Drive switches for 11 kv Dissconectors LED lamp lighting for buildings LED lamp lighting for buildings Perimeter lighting Exterior lighting Air conditioning systems Axial fans Central heating boiler

7 Power consumption after savings (kw) 15 Electric heating 16 Boiler Submersible pumps Electro pumps Other consumers relay protection containers Section 1 and 2 for kv Household consumers (fridge, microwave, TV, etc) 22 Workstations (PCs) metering, protection, management, etc. 23 Personnel PC workstations Video surveillance, intrusion detection, alarm, etc. Total power consumption (kw) Table 9. Energy consumption of the substation during a hot summer day after energy savings 1 Energy consumption summer day after savings Time interval(h) Diagram 3. Energy consumption of the substation during a hot summer day after energy savings In a cold winter day consumption scenario we analysed the consumers during the 24 hours interval after applying the energy saving methods. The results will be shown in Table 1 and Diagram Cooling batteries for Trafo 25 MVA /11 kv Cooling batteries for Trafo 16 MVA 11/ kv Fire detection and extinguishing systems Sergi 4 Drive switches for kv Circuit breakers Drive switches for 11 kv Circuit breakers

8 Power consumption after savings (kw) 6 Drive switches for kv Dissconectors Drive switches for 11 kv Dissconectors LED lamp lighting for buildings LED lamp lighting for buildings Perimeter lighting Exterior lighting Air conditioning systems 13 Axial fans Central heating boiler Electric heating Boiler Submersible pumps Electro pumps Other consumers relay protection containers Section 1 and 2 for kv Household consumers (fridge, microwave, TV, etc.) Workstations (PCs) metering, protection, management, etc Personnel PC workstations Video surveillance, intrusion detection, alarm, etc. Total power consumption (kw) Table 1. Energy consumption of the substation during a cold winter day after energy savings After applying the energy saving methods the energy consumption in the two scenarios analysed is: - Hot summer day = 675 kwh/day; - Cold winter day = 9 kwh/day. 1 Energy consumption winter day after savings Time interval(h) Diagram 4. Energy consumption of the substation during a cold winter day after energy savings

9 After applying the energy saving methods the energy consumption in the two scenarios analysed is: - Hot summer day = 675 kwh/day; - Cold winter day = 9 kwh/day. The compared energy consumption diagrams for summer time (kwh/day): Hot summer day initial substation Hot summer day after applying energy saving The total energy saving during summer will be 5,2 %. The compared energy consumption diagrams for winter time (kwh/day): Cold winter day initial substation Cold winter day after applying energy saving The total energy saving during winter will be 18,8 %. 6. DEFINING THE SURFACES THAT CAN BE USED FOR INSTALLING THE WIND TURBINES AND PHOTOVOLTAIC PANNELS AFTER THE REFURBISHING OF THE HIGH VOLTAGE SUBSTATION The /11/ kv Gura Ialomitei substation was rehabilitated by changing the technical solution from AIS technology to GIS technology. After the rehabilitation a large area of about 245 sqm remained available for installing the renewable power sources. 7. CHOOSING THE RENEWABLE ENERGY MIX DEPENDING ON THE WIND SPEED AND SOLAR RADIATION IN THE GEOGRAPHICAL AREA By replacing the old kv and 11 kv stations with GIS (Gas Insulated Switchgear) stations, a large area of land remained available. We used the remaining useful space for installation of wind turbines and photovoltaic panels. Average annual wind speed map for Romania:

10 For installation of wind turbines we used two surfaces of m 2 and 4 3 m 2. We chose Envergate ev1 wind turbines with an installed power of kw, with a yield of about 25% based on annual average wind speed. The characteristics of Envergate ev1 are presented in table below: Zone 1 Parameter U.M. Value Installed power kw Blades scale m 12 Rotor diameter m 8 Standard height of pillar m Annual performance at 4m/s kwh Annual performance at 6m/s kwh 887 CO 2 annual reduction at 6m/s t 54 Table 11. Technical specifications for the chosen wind turbines 1 st zone is a land with the area of about sqm where we will install about 75 wind turbines disposed as shown in the above drawing. Legend: - yellow circles = wind turbines with height of 24 m; - white circles = wind turbines with height of 16 m. Installed power = 3 MW. Zone 2 2 nd zone is a land with the area of about 43 sqm where we will install about 3 wind turbines disposed as shown in the above drawing.

11 Legend: - yellow circles = wind turbines with height of 24 m; - white circles = wind turbines with height of 16 m. Installed power = 1,2 MW. With the data above, the annual wind speed average in Gura Ialomitei area and considering that on the expected area we can place a maximum number of 15 wind turbines, the following results we obtained: Energy produced by the wind turbines during a year = 61 MWh/year. Energy consumed by the substation during a year = 235 MWh/year. Average annual and monthly solar radiation map for Romania: After installing the wind turbines a space of about sqm will remain for the photovoltaic panels to be installed. The panels will have a nominal installed power of about 2 W. There will be a number of about 19 panels. The total installed power will be of about,45 MW. Energy produced by the photovoltaic panels during a year = 5 MWh/year. Energy consumed by the substation during a year = 235 MWh/year. 8. TECHNICAL AND ECONOMICAL ANALYSIS For the scenarios mentioned in the last chapter and the geographical evolution of wind speed and solar radiation for Gura Ialomitei area we have chosen an average mix of energy of about % wind and % solar that will cover the substation need of energy in most of the times. The energy remained after covering the substations needs will be sold on the Romanian Energy Market. The funding schemes for renewables in Romania is the following: - for wind: the price of the energy/mw (the price of one MW can be around Euro) + 2 green certificates (the price of a green certificate may be between 3 and 55 Euro for one); - for photovoltaic: the price of the energy/mw (the price of one MW can be around Euro) + 4 green certificates (the price of a green certificate may be between 3 and 55 Euro for one); So for one MW produced from wind the investor can be paid 15 Euro and for one MW produced from solar the investor can be paid 2 Euro. Total investment for the wind turbines in Gura Ialomitei substation = 6.3. Euro. Total investment for the photovoltaic panels in Gura Ialomitei substation = 75. Euro. Total turnover for wind park / year = 7. Euro. Total turnover for solar park / year = 1. Euro. Total cost for the energy consumed by Gura Ialomitei substation for a year = 23. Euro. Total cost for heat pups = 59. Euro. Total cost for LED lighting = Euro. Life time for the wind turbines = -25 years. Life time for PV panels = 15- years. Life time for heat pump = 15 years. Life time for LEDs = 1 years. Amortization of wind park = 9 years (with current funding scheme); Amortization of photovoltaic park = 7 years (with current funding scheme); Amortization of heat pump = 9 years. Amortization of LEDs = 5 years. All the production and saving methods chosen prove to be feasible by the calculations shown in the paper. Besides this we will manage to reduce pollution by tons of CO2 a year.