Page 203 - Renewable Energy Devices and System with Simulations in MATLAB and ANSYS
P. 203

190             Renewable Energy Devices and Systems with Simulations in MATLAB  and ANSYS ®
                                                                                ®

              A wind farm equipped with DFIG-based WTSs is shown in Figure 8.14a. Such a wind farm system
            is, for example, in operation in Denmark as a 160 MW offshore wind power station. It is noted that due
            to the limitation of the reactive power capability, a centralized reactive power compensator like a static
            synchronous compensator (STATCOM) may be needed in order to fully satisfy the grid requirements.
              Figure 8.14b shows another wind farm configuration equipped with a WTS based on a full-scale
            power converter. Because the reactive power controllability is significantly extended, the grid-side
            converter in each of the generation unit can be used to provide the required reactive power individu-
            ally, leading to reactive power compensatorless solutions.
              For long-distance power  transmission from an offshore wind farm, HVDC  is an interesting
            option because the efficiency is improved and no reactive power compensators are needed [64, 65].


                                                       MVAC grid


                                  AC     DC
                                    DC    AC


                                                                  HVAC grid


                                                       Reactive power
                                  AC     DC             compensator
                      (a)           DC    AC


                                 AC     DC            MVAC grid
                                   DC     AC





                                                                 HVAC grid
                                 AC     DC
                                   DC     AC

                      (b)

                                 AC     DC            MVAC grid
                                   DC     AC

                                                               AC           +

                                                                   DC       –
                                 AC     DC                                HVDC grid
                                   DC     AC

                      (c)

            FIGURE 8.14  Potential wind farm configurations with AC and DC power transmission. (a) DFIG system
            with AC grid. (b) Full-scale converter system with AC grid. (c) Full-scale converter system with VSC rectifier
            and transmission DC grid.                                             (Continued)
   198   199   200   201   202   203   204   205   206   207   208