Innovation Pointe Progressive Energy Resource Park (PREP), an Application of Distributed Generation, Microgrid and Smart Grid

Transcription

1 2017 IEEE Rural Electric Power Conference Innovation Pointe Progressive Energy Resource Park (PREP), an Application of Distributed Generation, Microgrid and Smart Grid Todd Hiemer, PE Senior Member, IEEE Smart Energy Source 3305 S. Boomer Rd Stillwater, OK Abstract This paper discusses the introduction to Smart Energy Source s (SES) Progressive Resource Energy Park (PREP) and PREP design processes. The PREP application to Central Rural Electric Cooperative s Innovation Pointe campus microgrid. The microgrid consists of solar distributed energy resource (DER), battery energy storage and emergency diesel generation. This microgrid is controlled by a medium voltage switchgear and microgrid controller that utilizes smartgrid features to two different distribution substation. Index Terms Distributed Power Generation, Energy Efficiency, Energy Management, Green buildings, Microgrids, Power Grids, Power System Interconnection, Renewable Energy Sources, Smart Grids I. Introduction Today the energy sector is hearing phrases such as game changing to describe the current and future state of the energy industry. Business leaders are expecting that the utility industry will see more change over the next decade than the past seven decades combined largely because of exponential technologies and social changes. As a result of a confluence of factors (i.e., technological innovation, public policy support for sustainability and efficiency, declining trends in electricity demand growth, rising price pressures to maintain and upgrade the U.S. distribution grid, and enhancement of the generation fleet), the threat of disruptive forces (i.e., new products/markets that replace existing products/markets) impacting the utility industry is increasing and is adding to the effects of other types of disruptive forces like declining sales and end-use efficiency. 1 To provide an example of this trend, Central Rural Electric Cooperative (Central) faced unprecedented growth from the oil and gas industry starting back in Those customers were requesting service capabilities in excess, to what was really proved out in time, to be in excess of what was really needed. To manage the growth and future risks, Central implemented the Capacity Integration Model (CIM) to determine real and appropriate load requirements and capacity allocations. Central started looking to right sizing infrastructure and establishing a balanced cost and risk allocation between the utility and customer. The right sizing required investigation into actual load profiles over time and proposed detailed project scheduling. Central created Innovation Pointe as a micro community containing a 70 acre business park located near the intersection Yuvaraj Kondaswamy, PE Member, IEEE Smart Energy Source 3305 S. Boomer Rd Stillwater, OK ykondas@smartenergysource.com of 32 nd Street and Perkins Road in Stillwater, OK. The first tenant in the Innovation Pointe business park is Central s new headquarters building, which contains a tier II data center. Central s requirements were to increase reliability and reduce down time. Central also wanted to leverage new technologies like distributed generation and renewables for corporate social sustainability. Because of Central s strategic approach to become a next generation utility, it created a company called Smart Energy Source LLC (SES) to help facilitate new utility business models along with other utilities interested in becoming the next generation utility. SES strives to be at the forefront of change by providing proactive, valuable energy solutions that Central cannot. SES has developed a partnership with Oklahoma State University s National Energy Solutions Institute (NESI) to develop research for applied solutions related to energy, which includes a DER/Microgrid study. Central wanted to leverage Innovation Pointe micro community as a resource for advanced studies with this ecosystem relationship. A. PREP Definition The DER/Microgrid study, CIM and industry trends shaped the concept of how to utilize distributed resources, energy efficiency and existing infrastructure to form Progressive Resource Energy Park (PREP) application to solve energy needs. PREP is a design process that focuses on optimizing existing electric utility infrastructure, utilizing new technologies for energy delivery and to control consumption, smart interconnection of resources and to enable business processes to capture value. SES s PREP is more than just a name and an engineering process, it encompasses a business model that s taking proactive strategies to transform the energy industry landscape. PREP is facing energy industry challenges by embracing opportunities to make a more modern grid by integrating the new technologies with new techniques. PREPs take smart applications, energy efficiencies, engineering consulting, energy management and planning, and data monitoring/hosting to a new level by integrating them in one location to maximize the benefit of these services. PREP is a model of limitless solutions that can change with technology and be enabled in various forms depending upon circumstances and requirements of the particular application /17 $ IEEE DOI /REPC

2 The approach is the same for all different site applications but with individual solution results for each site. The PREP strategy map, shown in figure 1 below, indicates the five fundamental elements that comprise PREP. The strategy map shows the three different levels (Tiers) that PREP can develop into depending upon the goals for each particular implementation. With the world experiencing a period of urbanization, building cities that the world needs require smart planning and utilization of infrastructure. We need a scientific understanding of cities that considers our built environments and the people who inhabit them. 2 This requires building an efficient and smart infrastructure, which PREP can be a tool incorporated into urban planning to facilitate this sustainable growth. PREPs will encompass the latest in research-driven Park a hub for smart grid functions that eliminates duplicate services and increases economies of scale, financial opportunities and reliability II. Analytics and Progressions As mentioned earlier about Central s CIM process, the focus on the PREP design was to optimize energy delivery and consumption. PREP looks at all technologies and resources like: biomass generation, energy storage, fossil fueled generation, smartgrid, solar generation, virtual generation (energy efficiency and load control), wind generation or any future technology. The following sections will provide more details of Innovation Pointe s business campus application of PREP. technologies and solutions that will help cities address change and take a smarter step forward in implementing intelligent infrastructures to support electric energy supply. They will prepare cities for unprecedented change and growth with the use of new technologies for more intelligent grids and metering that can enable city energy networks to dynamically respond to human behavior patterns in energy use. The PREP is: Progressive - in its strategies Resourceful - in renewable and efficient energy solutions Energy delivered in a modern grid package Figure 1 - PREP Strategy Map A. Headquarters facility Central s headquarters facility was designed considering energy usage and how to minimize consumption. That consideration was implemented with two major focuses: Leadership in Energy and Environmental Design (LEED) and Building Automation System (BAS). Because of Central s and SES s current and future needs, the building contains a Tier II data center and system operations center. The uptime expectations for the data center drove the requirement for increased electric service uptime because data center outages 83

3 are very costly. This requirement precipitated the smartgrid and self-healing techniques onto the two feeders (Ramsey feeder #2 and Williams feeder #3) that connect to the Innovation Pointe campus. The last three year average for both feeders of ASAI was % and SAIDI was 233 minutes. The Architect / Engineering firm s design load for the headquarters building was 769 kva. This is a NEC driven load value which is designed to prevent fire hazards and design in growth safety factors. Therefore, it was not expected that the headquarters building would actually see that much load and anticipated to only need 448 kva. The headquarters building expected daily electrical load was to be about 4,500 kwh. The four other existing buildings on the campus have three year maximum demand of 90 kw and average demand of 78 kw. This equates to maximum daily usage of 950 kwh and average daily usage of 751 kwh. Future plans for the campus envisions up to four more building similar to the headquarters building, so future expansion must be available. Ground Source Loop: Wells for the closed loop ground source system was chosen to reduce the new headquarters building interior space conditioning load by 25 to 50 % of electrical energy consumption. The campus has two groupings of wells, one small grouping (8 wells) and one large grouping (98 wells). The larger well grouping was sized to handle facility expansion on the campus. All wells are 400 feet deep and have their precise locations mapped by global position system to facilitate asset management and future expansion. Lighting: LED lighting was chosen to reduce the new headquarters building to reduce electrical energy use by 75% of lighting energy. The lighting system also includes occupancy sensors in most rooms to minimize lighting and therefore energy usage. Building Automation System: The building automation system utilizes capturing usage data to provide information to manage the different systems within the building. The BAS will interface with the microgrid to provide real-time capabilities to match generation and building load. This will enhance the ability for the building to be a virtual energy source which will allow varying the building load to more closely match the solar output. B. Solar A photovoltaic (PV) power system can either be a standalone (off-grid system) or a grid-tied system. The Innovation Pointe business park campus solar system is a gridtied PV system which is connected directly to the utility distribution grid. The PV system provides power for the facility, and excess power is provided to the battery storage system and the distribution grid. The system is rated at kw DC; 504 kw AC with a DC to AC ratio. It consists of 1,680 solar panels each rated at 410 watts DC. The solar array orientation is configured to the South. The solar array is synchronized with the utility system via micro inverters and the nominal terminal voltage of the array is 480 / 277 volt AC, three phase. The solar array features an inherently redundant inverter bus architecture with the modules connected in parallel, so any single failure will have minimal impact on the system production which helps in maximizing system uptime and higher solar output energy. Stillwater has an average monthly Global Horizontal Irradiance (GHI) of 5.41 kilowatt hours per square meter per day 3. The GHI varies with the month or seasons, but the average daily production is expected to be 2,586 kwh / day. The solar was expected to cover about 50% to 60% of the daily energy usage of the campus. This conservative sizing approach would allow to expansion into the proper size for Innovation Pointe net zero or even virtual off grid operations. C. Battery To mitigate the impact renewable energy integration, especially with changes in the solar array power production which can exceed 50% of the name plate generation rating over a one second interval. Data from first four months of operational data has shown a maximum rate of 425 kw/s of change in solar production. The Battery Energy Storage System (BESS) is introduced into the Innovation Pointe PREP to insure system stability along with the possibility to arbitrage the solar energy to non-sunlight hours. The BESS was sized like the solar to step into the proper future size with appropriate sizing to facilitate operations and research and to maximize the use of sustainable energy and facilitate grid stability support. Innovation Pointe s BESS is rated at 250 kw / 475 kwh, 480V, three phase system. The BESS consists of five battery packs each rated 100 kw, with the battery packs combined by a DC combiner panel, a bi-directional inverter and a site master controller. D. Diesel Generator The diesel generator is rated 750 kw, minimum power factor of 0.8 lagging at 277 / 480 volts. The generator is sized in taking the following considerations, peak loads of the campus, power factor, single phase loads and load imbalance, low-inertia loads, uninterruptible power supply, high-inertia loads and VFD drives, voltage and frequency dips during startups and possible future expansion. With all these factors in consideration, the generator set is sized to pick up all required loads with the ability to satisfy the campus demand peaks, even in the case of solar absence and fully discharged battery. The generator investment cost was balanced to set size and availability. The rule of thumb to prevent inrush current problems has been to oversize the generator by a factor of three. E. Smartgrid The solar array, BESS, diesel generator and HQ campus load are integrated with the grid through a 25 kv S&C Vista Switchgear. Switchgear comprises of six independent ways with fault interrupter switches on each way. Each fault 84

4 interrupter is controlled by a SEL-751 relay. Step-up / down transformers (25 kv / 480 line to line voltage) are used for Solar PV array, BESS, diesel generator and Innovation Pointe campus load to integrate the system at the switchgear level. Grid interconnection and automation scheme is controlled by Real Time Automation Controller (RTAC which is a SEL- 3530). The system one line is represented in Figure 2 below. Switchgear is tied to the grid feed by two different Fuse Saving Vs Fuse Blowing Reclosing Out of Synchronism Feeder Reconfiguration The reclosers adjacent to Innovation Pointe campus are the Ramsey Office West and the Williams Office West reclosers. The main design criteria require that only one of the two reclosers are closed at any instant. Thus the Innovation Figure 2- Innovation Pointe Single Line Diagram substations. The microgrid controller employees six SEL- 651R recloser control for feeder protection. Unlike traditional distribution analysis, which is done at a few meaningful time points (e.g., heaviest load), impacts of renewable energy integration should be investigated in a detailed fashion. Following design criteria are taken into consideration while setting up the SEL-651R Reclosers: Overload impacts Cold Load Pickup Undervoltage/overvoltage Reverse Power flow Fault Current and Interrupting Rating of solar array, BESS and Diesel generator Pointe campus will be energized from either the Ramsey substation or the Williams substation. This arrangement prevents faults on Ramsey feeders being fed from the Williams substation and faults on Williams feeder energized from the Ramsey substation. The auto reclose function of the Williams and Ramsey sequences are set to achieve the following objectives: Minimize blinks on the distribution feeders serving customers. Employ optional fuse saving scheme. Fuse saving scheme can be disabled with push button control. Prevent inadvertent energization of faults on Ramsey feeder from Williams feeder. Similarly prevent 85

5 energization of faults on Williams feeder from Ramsey feeder. The source recloser relays (651R Ramsey Source and 651R Williams Source) was set to operate for fuse saving mode. Under this mode, the reclosers will attempt to avoid a fuse blowout for temporary faults on the feeders. The reclosers will be set to trip instantaneously on a low set overcurrent element and will reclose automatically after a set time delay. The reclosers were set to operate on 1A2C mode, i.e. one fast three slow operations. The fuse must not melt during the recloser fast operation but the fuse must melt during the recloser slow operation. While temporary faults are expected to be cleared before the first close operation, permanent faults are expected to last longer. The downstream fuses / sectionalizers are required to melt/open for permanent faults and clear the fault. The second and third recloser shot trip times are set to coordinate with fuse melting times to allow downstream fuses / sectionalizers to clear the fault and resume service to other customers. The relay s slow operating curves will be coordinated with the 651R Midline, 651R Office reclosers and the relays in Innovation Pointe campus. Based on the design changes and operational requirements, Fuse saving scheme has been disabled by disabling the low set instantaneous overcurrent element and the trip time for all three shots is determined by the slow operating curves. Similar setting philosophy were used for Ramsey Midline and Williams Midline Reclosers. The Innovation Pointe Vista Switchgear is designed to be connected to either Williams 3 or Ramsey 2 feeder. Under normal operating conditions either 651R Ramsey Office or 651R Williams Office are closed and the other recloser is open. For faults on Ramsey feeder, 651R Ramsey Office will trip and 651R Williams Office is closed. The conditions for closing Williams recloser are listed below: a. Williams feeder is available (i.e. Williams Source, Williams Midline breakers are closed and voltage on the feeder is healthy). b. Fault on Ramsey feeder is established by trip of 651R Ramsey Midline or 651R Ramsey Source reclosers. c. No fault detected on Innovation Pointe campus distribution feeder and 651R Ramsey Office recloser has no overcurrent elements picked up. When the above conditions are satisfied 651R Office Ramsey will send a close command to 651R Williams Office via GOOSE communications and the Innovation Pointe Campus will be energized from Williams instead of Ramsey. Similarly, when the Innovation Pointe campus Vista switchgear is energized from Williams i.e. 651R Williams Office is closed and 651R Ramsey Office is open and a fault occurs on Williams feeder, the Ramsey 651R Office recloser will be closed when the following conditions are satisfied. a. Ramsey feeder is available (i.e. Ramsey Source, Ramsey Midline reclosers are closed and voltage on the feeder is healthy). b. Occurrence of fault on Williams feeder and trip of 651R Williams Midline or 651R Williams Source reclosers. c. No fault detected on Innovation Pointe campus distribution feeder and 651R Williams Office recloser has no overcurrent elements picked up. Isolating renewable sources for any fault in the system played a significant role in designing the RTAC control and communication schemes. The SEL-651Rs are configured for IEC Goose messaging utilizing high speed fiber communication infrastructure to transmit and receive messages from the RTAC. The RTAC is programmed for feeder reconfiguration schemes, fault isolation and dead-bus detection scheme to start the diesel generator in case of grid failure. All SEL IEDs communicate via DNP3 to the SEL-3530 RTAC in the Innovation Pointe campus. The RTAC also communicates via DNP3 to the SCADA system and via Modbus to the diesel generator. High speed data including faulted open signals and switch open/close commands communicate via IEC GOOSE protocol to the RTAC. The RTAC has two real-time threads that aggregate status information and pass controls back to the SEL relays. The threads are summarized below: Four milliseconds real time: This thread includes the switching algorithm, interlocks, digital input processing, the output (trip) processing, and communications processing. 200 milliseconds real time: This thread handles analog data processing for the analog data. This thread also includes DNP3 communication to all SEL relays and SCADA. In addition, the switchgear and all the reclosers employees the SEL-2730M managed Ethernet switch. These switches have been configured with VLANs to prevent broadcast storms and to restrict IEC GOOSE traffic. There is an SEL that provides IRIG-B time synchronization to all the relays. Conceptually, the scheme is divided into two functional categories: pre-event calculations and event actions. The system performs pre-event calculations to dynamically determine the switches to trip and when to close the emergency diesel generator switch. The system monitors trigger signals and generates trip signals when a trigger is detected based on the RTAC automation operational scheme at the switchgear 4. F. Microgrid schemes The normal configuration is the grid sourced from the Ramsey substation with the 651R Office Williams open. The solar, battery, distribution grid and the campus bus are connected together through the multi-port medium voltage switch. Distribution switching equipment senses the distribution system health and communicates with the micro- 86

6 Grid control for energy supply coordination. The microgrid control will automatically switch between substation feeds in less than 0.1 seconds if the selected source fails. The micro- Grid control equipment will control connectivity for all energy sources. If a fault is detected on the distribution system, the microgrid controller will disconnect Innovation Point generation resources (battery, generator and solar) to prevent feeding a distribution fault. The protection and control scheme is shown in figure 3, below. A. Net zero The campus has been net zero (actually produced more generation than load) for the first four months of operation (August through November). The campus is not currently capable of virtual off grid yet without some resource modifications that will be addressed in the following paragraph. Solar Generation & Load (kwh) 270, , , , , ,000 90,000 60,000 30, ,000-60,000 Aug-2016 Sep-2016 Oct-2016 Nov-2016 Total Figure 3 - Protection / Control Scheme III. Results We have only been able to really start collecting since the start of August. Figure 4 shows typical daily energy levels for a good solar summer day. The long range goal was for the Innovation Pointe campus to be capable of virtual off grid operation, but the short term campus goal is to be net zero, which has been achieved for the first four months of operation as shown in figure 5. The Department of Energy (DOE) defines net zero be consumption and local generation to be equal over the period of a year. Most net metering time periods are over the billing period which is a month. 500, , ,000 (100,000) (300,000) Solar Battery Building Grid / Net Figure 4 - Typical Daily Summer Energy Usage B. Reliability Figure 5 - System Net Energy Because the headquarters facility contains a Tier II data center, the emphasis on maximizing reliability and uptime at the Innovation Pointe campus. Therefore, the emphasis on smart and self-healing approach was implemented. The reliability and availability number was shown in a previous section. The microgrid has already mitigated an outage of 110 minutes for 739 members to just a few seconds at the Innovation Pointe campus. This was an outage on the Ramsey feeder which was the designated feeder for the microgrid before the incident. The microgrid self-healed the campus location to the Williams feeder within 12 cycles instead of the 110 minute outage. C. Sizing implications Solar HQ Load Delta Currently, we believe the solar is sized appropriately because of the over generation in August and under generation in November, but August should be a better solar production month. August was also expected to be a higher energy usage because of weather temperature and the related increased air conditioning load. We believe the battery s 250 kw is currently sized appropriately but the sustain energy (475 kwh) should be two to three times larger to achieve off grid status. The backup generator is sized about twice as big as needed because of lower demand load from the major campus load 87

7 (headquarters building), which also decreases the inrush current. D. Lessons learned The microgrid operates as expected, but expectations for reliability and uptime are very high. We believe that with a software update to allow island mode operation will allow the battery system to bridge all short switching events to provide continuous service for the campus. Peak shaving with the battery system and diesel generator to discharge at times of peak demand to avoid or reduce demand charges. Emergency backup from battery system to provide intermediate bridging power to the park in the event of a grid interruption. Integrate solar forecasting into BAS operations to reduce load requirements during low solar production. Knowledge feedback into the design cycle to improve design decisions. E. Future Projects References 1 Peter Kind, Disruptive Challenges: Financial Implications and Strategic Responses to a Changing Retail Electric Business, Edison Electric Institute (EEI), 701 Pennsylvania Avenue, N.W. Washington, D.C., January MIT Media Lab, (2016, October 17), Cities Network, MIT Media Lab Changing Places Group, Available: 3 National Renewable Energy Laboratory (NREL), (2016, October 3), NSRDB Data Viewer, Available: 4 Schweitzer Engineering Laboratories (SEL), provided protection functional design specification, _SEL_0003.pdf. 5 Hiemer, Todd and Yuvaraj Kondaswamy, Innovation Pointe PREP Microgrid, Frontiers of Power Conference, Stillwater, OK, November