Project: Western Alberta Transmission Line (WATL) HVDC Project Client: AltaLink Attachment 3 Full Project Description ACEC Canada – Canadian Consulting Engineering Awards 2016 Project: Western Alberta Transmission Line (WATL) HVDC Project Client: AltaLink Consultant: Teshmont Consultants LP Project: Western Alberta Transmission Line (WATL) HVDC Project Introduction Few projects in the realm of electric power transmission are as complex and costly as the development of a high voltage direct current (HVDC) transmission system. However, properly developed, HVDC systems can be one of the most reliable and cost effective means of transmitting power. In 2010, Teshmont Consultants LP (Teshmont) was engaged by AltaLink to act as Owner’s Engineer for the Western Alberta Transmission Line (WATL) HVDC Project. WATL is the first HVDC system in service in Alberta and began transmitting power on December 10, 2015. The 500 kiloVolt (kV) line spans 350 km and connects the two major load centres of Calgary and Edmonton. HVDC technology was selected for this project because it provides significant improvement in performance over traditional alternating current (AC) transmission, having increased transfer capability, lower transmission losses, lower overall lifecycle costs over longer distances, as well as helping to improve overall system stability. The $1.65 billion project spanned five years and was technically challenging with a demanding schedule involving the client, several contractors, and a variety of other key stakeholders. Technical Background and Information Modern electric power systems work utilizing AC to generate, transmit, and distribute electricity to consumers. The AC voltages and currents change polarity at either 60 times per second (as in North America) or 50 times per second (as in Europe). HVDC, on the other hand, is transmitted using a constant voltage and current with no regular changes in polarity. In order to accomplish this, HVDC transmission requires the use of specialized equipment to convert the AC power that is generated to constant DC power. The DC power is then transmitted over HVDC transmission lines or cables to a destination where it is then converted again back to AC for onward delivery to consumers. The converter stations at either end of an HVDC line or cable consist of specialized equipment that needs to be uniquely designed and integrated specifically for each project application. This equipment includes converter transformers, converter valves and valve cooling systems, DC reactors, AC and DC filters, high voltage breakers and switches, as well as control, protection, and communication systems. HVDC offers a number of benefits over the use of traditional AC transmission. The significant benefits can be summarized as follows: • HVDC has lower electrical losses than AC transmission and, therefore, despite the additional cost of the conversion equipment, HVDC becomes more economically advantageous at longer distances. • HVDC results in the electrical isolation of sending and receiving end AC systems, which allows for power transmission between asynchronous AC systems that are not currently interconnected and may even be 2016 ACEC Canada Awards 1 Project: Western Alberta Transmission Line (WATL) HVDC Project Client: AltaLink Consultant: Teshmont Consultants LP operating at different frequencies. This isolation minimizes the impact of network disturbances in one of the interconnected systems on the other. • HVDC allows for precise controllability of transmitted power, which can be used to increase the overall reliability of the surrounding AC transmission system(s). The HVDC system can also be used to address a number of issues that may be present within the AC network (reactive power problems, frequency regulation, power swings, etc.). • HVDC is particularly well suited (especially voltage sourced converter (VSC) HVDC technology) for the integration of renewable energy sources, which are often located a significant distance away from major load centers or offshore requiring the use of submarine cables. • Lines and cables transmitting HVDC power conduct electricity more effectively than AC, which allows for greater power density to be transmitted along physically and/or electrically constrained rights-of-way. • As opposed to AC where charging currents technically limit the practical length of high voltage cables to 40 to 50 km, HVDC poses no such limitation and can be used for very long submarine or terrestrial cable installations. • Because HVDC is more efficiently transmitted and only requires two conductors versus three conductors for AC, HVDC lines can be constructed on smaller towers along narrower rights-of-way. This reduces the environmental impact of an HVDC line as compared to similarly rated AC circuits and also reduces the installed cost per kilometer of transmission. Project Description and Teshmont’s Scope The WATL HVDC transmission line is 350 km long and runs between the Genesee area southwest of Edmonton and the Langdon area east of Calgary. The route, shown in Figure 1, runs parallel to existing 240 kV AC circuits for approximately 60% of the distance between Edmonton and Calgary. Construction on the project began in 2012 with crews logging over 5.6 million hours of work over a three year period. The line was constructed using over 3500 km of wire and 20,000 tonnes of steel to construct 950 structures along the route. At the peak of construction, the project employed 1200 people. Figure 2 shows contractors stringing a section of the line. In addition to the transmission line, two new HVDC converter stations, Crossings in the South and Sunnybrook in the north, as well as two AC substations were constructed at either end of the line. At Crossings Converter Station, a Static Compensator (STATCOM) was also installed. Other elements of the converter stations included DC filters, DC smoothing reactor, valve cooling, converter transformers, AC filters, and an HVDC converter building that contains the converter valves, as well as the control, protection, and communication systems. An aerial view of the Crossings Converter Station is shown in Figure 3. 2016 ACEC Canada Awards 2 Project: Western Alberta Transmission Line (WATL) HVDC Project Client: AltaLink Consultant: Teshmont Consultants LP Figure 1: WATL Route Figure 2: Transmission Line Stringing 2016 ACEC Canada Awards 3 Project: Western Alberta Transmission Line (WATL) HVDC Project Client: AltaLink Consultant: Teshmont Consultants LP Figure 3: Crossings Converter Station in the Langdon Area In 2009, Teshmont was engaged by the Alberta Electric System Operator (AESO) to perform system planning studies to determine the functional requirements for the potential development of two HVDC projects in Alberta – WATL and the Eastern Alberta Transmission Line (EATL). The results of these studies were used by Teshmont to prepare functional technical specifications for both of the HVDC projects. These functional technical specifications were issued by AESO to the two major transmission facility operators (TFO) in the province. AltaLink, a Berkshire Hathaway Energy Company located in Calgary, would develop WATL, while ATCO Electric would develop EATL. In the fall of 2010, AltaLink turned to Teshmont to act as Owner’s Engineer for WATL to provide them with the technical guidance and leadership they required to successfully design, procure, construct, and operate this HVDC system. Over the next five years, Teshmont’s scope was comprehensive and broken down into distinct phases and stages as follows: Phase 1 – Equipment Studies and Specification Development During Phase 1, Teshmont performed a variety of equipment rating studies to determine the exact requirements of the key components of the converter stations. These detailed studies were based on the functional specifications Teshmont previously prepared for the AESO. The results of these studies were then used by Teshmont to prepare the comprehensive technical specification for an engineer, procure, and construct (EPC) request for proposal (RFP) issued by AltaLink for the design, manufacture, delivery, construction, and commissioning of the two converter stations required for the first stage of the WATL project. In addition to preparing the technical specification, which was over 400 pages, Teshmont also assisted AltaLink in the preparation of the commercial terms of the agreement. 2016 ACEC Canada Awards 4 Project: Western Alberta Transmission Line (WATL) HVDC Project Client: AltaLink Consultant: Teshmont Consultants LP Phase 2 – Bid Evaluation and Contract Award After a three month tendering period, Teshmont performed a comprehensive and detailed review of the bids submitted to evaluate conformance to the specifications and to assess the different offerings from a technical standpoint in order to provide AltaLink with a ranking of the bidders on a technical merit and value basis. The review also included a series of clarification questions and associated responses. Once a preferred bidder was identified, Teshmont supported AltaLink through the contract negotiations and prepared a conformed specification at the end of negotiations, which encapsulated all of the changes to the original specification that were agreed upon during the negotiations. The final contract for the converter stations was awarded to Siemens of Germany. Phase 3 – Design, Manufacture, Installation, and Commissioning The third phase of the project was broken down into four distinct stages as follows: Stage 1: Design Review – During