Development of a 15 MW Hardware in the Loop Electric Grid Test Facility
怎样快速记单词
Thomas E. Salem J. Curtiss Fox Clemson University Clemson University 1250 Supply Street1250 Supply Street
N. Charleston, SC USA tsalem@clemson.edu N. Charleston, SC USA jfox@clemson.edu
Abstract
To expedite market penetration and to facilitate the development of technologies in the re-newable energy wind ctor, Clemson University is constructing a Wind Turbine Drivetrain Test Facility at its Restoration Institute located in North Charleston, SC. Houd in this facili-ty are two turbine drivetrain test stands, one rated at 7.5 MW and the other at 15 MW of shaft power capability. Each test stand has been designed to provide both static and dynamic mul-ti-axial shaft loading of the turbine drivetrain equipment through a controllable hydraulic load application unit. This tup provides the necessary capabilities for accelerated lifetime me-chanical testing and evaluation.
Additionally, the facility incorporates the electrical performance evaluation of the turbines through their connection to a 15 MW multi-level power amplifier with arbitrary waveform gen-eration capability.
The electrical test apparatus also includes a reactive divider which ena-bles the complete system to conduct low voltage ride-through and high voltage ride-through testing for the wind turbines. Although electrical testing of the wind turbines is necessary, it is anticipated that it will only be conducted on a periodic basis. Therefore, with the required level of sophisticated electrical test equipment for low voltage ride-through already being in-stalled; a real-time digital power system simulator is also being installed to create a 15 MW hardware in the loop electric grid test platform. This paper details the development strategy and implementation effort for realizing the electrical test portion of the overall facility and its unique capabilities for multi-megawatt evaluation of power grid components and technolo-gies.
1. Introduction
1.1. Wind Turbine Drivetrain Test Facility
In November of 2009, Clemson University was awarded a competitive grant from the U.S. Department of Energy to build and operate a facility for full-scale, highly accelerated testing of next-generation wind turbine technology [1]. Shown in Fig. 1, the faci lity’s objective is to provide a shared resource to accelerate the development and deployment of next-generation wind turbine tech
nology with the ultimate goal of reducing the cost of energy delivered [2]. The facility, prently in the final stages of construction, is strategically located in North Charleston SC, providing easy transportation access by rail, road or ship. The Wind Turbine Drivetrain Facility (WTDTF) operates on an open access model and is available to the world-wide community for rearch, analysis, and evaluation activities.
The 72 m by 97 m facility features two mechanical dynamometer test bays for evaluating the torque and blade dynamic forces experienced by the rotors of wind turbine nacelles. The dynamometers are rated at 7.5 MW and 15 MW of shaft power capability. Both bays are configured as independent test areas capable of simultaneous operation. All six degrees of freedom, three linear and three rotational, for blade and rotor dynamics are replicated through the combination of a drive motor and gearbox system and a controllable hydraulic load application unit (LAU). The LAU is comprid of ts of hydraulic pistons that interact
with a rotating disk connected in line with the drive motor and the turbine shaft. This tup readily supports accelerated lifetime mechanical testing and load analysis for the entire drivetrain system of the nacelle and easily replicates a wide variety of realistic operating sce-narios in a controlled laboratory environment.
加工合作
Fig. 1. Wind Turbine Drivetrain Test Facility, recent construction photo (left) and design layout (right) 1.2. Electrical Standards and Grid Integration Evaluations
With the incread market penetration of wind energy over the past veral years, many re-gions and countries have developed specific electrical grid codes for large wind farms to en-sure operational reliability and stability [3]. The grid codes provide requirements for inter-connection during low voltage phenomena, typically encountered during system fault events. Fig. 2, prents an overlay of veral international grid codes for low voltage ride-through (LVRT) events [4]. This graph depicts the time requirements for wind generators to remain connected to the grid during voltage sag events and has been modified to include the 2005 Federal Energy Regulatory Commission requirements [5].
Given the installed infrastructure of the WTDTF, a natural expansion of facility capability was to include the necessary equipment for electrical testing of wind turbines to the LVRT codes. Two options for LVRT were evaluated, one involving a power converter approach to fault emulation and the other involving a hardware implementation of fault events through a reac-tive divider network [6-7]. To accommodate testing at the 15 MW level, the decision was made to combine the techniques and supplement a power converter with a reactive divider network. This hybrid implemen
tation strategy optimizes the power requirements for the con-verter while fully enabling zero-voltage fault event testing in a robust manner.
Fig. 2. Various world -wide grid codes for low voltage ride -through
15 MW Dynamometer 7.5 MW
Dynamometer
工会管理办法HIL Electric Grid Area香肠嘴
Collocated within the WTDTF building is the Electric Grid Testing Facility (EGTF). The de-sign strategy for the EGTF was developed with the goals of maximizing flexibility and testing capabilities of the electrical system to meet nearly all grid integration challenges. Specifical-ly, an emphasis was placed on harmonic and voltage flicker evaluations from both a suscep-tibility and contribution frame
of reference. Building upon the inherent requirements for per-forming harmonic evaluations, the system is capable of recreating measured field events us-ing either an open loop or a clod loop, hardware in the loop (HIL), testing methodology. Table 1 outlines the available test capabilities at the EGTF.
Table 1: Testing capabilities of the Electric Grid Testing Facility
2. Electric Grid Test Facility
2.1. Overview
The objective of the Electric Grid Test Facility extends beyond just grid integration evalua-tions for wind turbines to include the testing of multi -megawatt scale solar inverters, utility scale energy storage systems, micro and smart grid technology systems, and even tradition-al distributed generation technologies (diel, natural gas, etc.). To achieve this objective the EGTF is configured as an independent test area collocated with the dynamometer test areas of the WTDTF. Fig. 3 depicts a simplified single -line electrical diagram of both test facilities and illustrates how they can operate independently or be easily coupled together for com-plete electrical testing of the wind turbines on the dynamometers. In Fig. 3, the 15 MW dy-namometer is shown on the left, the Electric
Grid Test Facility in the middle and the 7.5 MW dynamometer to the right. To connect either of the wind turbine dynamometers to the EGTF , switchgear is built into the system to allow for easy coupling of each Dynamometer Bus to the HIL Electric Grid Bus. When not being utilized for electrical testing with the WTDTF the Electric Grid Test Facility can be partitioned off and utilized for the testing of other devices in the electric grid test bay area.
2.2. Capabilities建立模板
写乌龟的作文Power Amplifier
The power amplifier, designed and fabricated by TECO -Westinghou Motor Company, fea-tures a multi -level ries connected half -bridge converter topology capable of four -quadrant operation at 20 MVA. The amplifier is fabricated in a modular fashion that readily facilitates ries and parallel configurations of amplifier ctions to obtain desired voltage and power levels. Each amplifier ction has internal electrical isolation allowing for connection configu-rations ranging from as low as 480 V up to 13.8 kV at the output terminals. The output volt-age frequency range of the amplifier is limited to 45 to 65 Hz for grid integration and electrical Steady State Power Quality and
眼镜狗
Ancillary Service Grid Fault Ride -Through
Open Loop Clod Loop Power Set Points Harmonic Low Voltage
Zero Voltage
Re-creation of field measured events Simulated dynamic behavior and interaction between grid and device under test Voltage Variations Voltage Flicker Unsymmetrical
Frequency Variations
Volt / VAR Control High Voltage Evaluation of Controls Frequency Regulation
testing scenarios, but other frequencies are also achievable. The ries connected half-bridge converter topology of the power amplifier inherently has a natural neutral point due to its star connection that allows for the development of zero quence voltages at the output terminals.
物理英语怎么读
The nominal operating voltage for the installed configuration of the 15 MW Electric Grid Test Facility is eight (8) parallel amplifier ctions with an output voltage of 4160 V and a continu-ous overvoltage capability of 133% at rated current. This ba configuration consists of four (4) ries connected half-bridge converters per pha. While only three (3) of the half-bridges are required for 4160 V operation, inclusion of the fourth allows for the continuous overvoltage capability. With respect to the
number of output voltage levels, this converter to-pology results in nine (9) levels per pha and venteen (17) levels line to line.
Through the u of pha-shifted carrier pul width modulation, a large degree of harmonic cancelation is achieved [8]. In the ba configuration, the first resulting noi mode will oc-cur at eight times the switching frequency of the individual half-bridge converters. Coupling this modulation technique with the u of low voltage IGBTs capable of switching frequencies into the low kHz, results in a weighted total harmonic distortion of less than 0.1% with a first noi mode over 10 kHz. Additionally, since the power amplifier is designed to sample refer-ence voltages at 12 kHz, this system is able to accurately control and replicate the low order harmonics that are commonly found on power systems.
Fig. 3. Simplified Single-Line Diagram
Reactive Divider Network
To augment the fault testing capability for the system, a reactive divider network has been designed to operate with the power amplifier. This hybrid method of performing fault ride-through evaluations greatly enhances the capabilities of using either a reactive divider net-work or power amplifier alone. The controllability of the power amplifier voltage allows for in-cread voltage regulation of the reactive divider network and the reactive divider network allows for a shunt path for fault current that reduces the fault duty requirements of the power amplifier. Fig. 4 demonstrates the operation of this hybrid method with the shunt element of the reactive divider network inrted into the circuit.
The reactive divider network system is easily reconfigurable and controllable to produce all possible fault conditions for a three-pha network, including symmetrical and unsymmetrical
fault conditions. The network us a combination of fixed and tapped air -core reactors, al-lowing for thousands of possible fault emulation values to be configured including zero -voltage fault conditions at the point of common coupling for a device under test. The reactor network is electrically isolated to accept fault duties up to 100 MVA and is thermally designed to operate at over 35 MVA for duratio
ns of 3 conds with a 10 minute duty cycle.
Fig. 4. Reactive Divider Network for Fault Emulation
Complete Testing Capabilities
Fig. 5 shows the complete voltage test range capabilities of the Electric Grid Test Facility, in-cluding the boundaries for high voltage and low voltage ride -through of the most restrictive grid codes which were ud during the design process to establish the operating capability requirements for the facility. The low voltage boundary of a zero voltage event can be achieved by either the power amplifier alone or by including the reactive divider network. The high voltage boundary reaches a maximum of 145% of the nominal voltage by combin-ing the 133% built in overvoltage capability of the power amplifier along with a 10% tap on the interconnecting HIL Electric Grid Bus transformers.
It should be noted that operating at 145% overvoltage occurs without saturation or clipping of the output voltage of the power amplifier. Having built in overvoltage designed into the power amplifier extends the capabili-ties of the facility by allowing low voltage fault events to be followed by brief periods of over-voltage which is a common grid occurrence. The phenomenon of Fault Induced Delayed Voltage Recovery is one such example of the need for coupling both LVRT and HVRT events
[9].
V o l t a g e i n P e r c e n t
Fig. 5. HIL Electric Grid Bus voltage capabilities
2.3. Hardware in the loop
To further enhance grid integration testing capabilities of the Electric Grid Test Facility, the ability to perform clod loop, hardware in the loop, testing has been designed into the sys-tem architecture. The concept of HIL testing involves controlling the t point operation the power amplifier, via a real-time simulation of a power system, such that a device under test
