BS 61975:2010 pdf download – High-voltage direct current (HVDC) installations — System tests
4.4 Logical steps of system test
To ensure proper functioning, the type test and functional performance test should be conducted in factory in order to debug and test the control system before the site test. In order to provide the power grid data and help to compile the system test plan, the off-line digital simulation should be conducted before and during the simulation test, especially analysis on the power flow, stability and overvoltage. Considering the complexity of the HVDC system, all limiting design cases may be conducted on the digital simulator in a similar way to those done on site. Commissioning an HVDC system may affect more than the actual contract parties. The complexity and the diversified areas concerned during system test require thorough planning and scheduling, cooperation of all involved parties and complete and structured documentation. Before a system test can begin on site, the following preconditions should be fulfilled concerning subsystem tests, operator training and safety instructions, system test plan and test procedures, and all necessary test equipment.
a) All subsystems should have been tested and commissioned, including a.c. filters and the converter transformers with special attention to possible transformer or a.c. filter resonance during energizing.
b) Operating personnel should be sufficiently trained.
c) Operating instructions for the station should be available.
d) Personnel, plant safety and security instructions should be available.
e) System test plan and documentation (Part 8) should be available and agreed upon.
f) AC/d.c. power profiles should have been agreed for each test.
g) Any a.c./d.c. system operating restrictions should have been identified.
h) Operator voice communications should be available
i) All necessary test equipment should have been calibrated and in service.
j) Procedures for the preparation and evaluation of test results should have been agreed upon. Site system tests should follow the structure of the HVDC system, starting from the smallest, least complex operational unit, usually a 1 2-pulse converter, and shall end with the total system in operation. The test sequence should be scheduled starting at the local level with simple tests before involving additional locations and the transmission system and more complex tests. After all preconditions are fulfilled, converter station tests should be conducted and begin from the converter unit test, including energizing of a.c. filter and d.c. yard, electrical magnetic interference, trip test, changing the d.c. system configuration, open line test, and so on.
The power transmission (also called end-to-end) test should start on a monopolar basis, with bipolar operation, with full power being the final step. Having the complete system running properly, performance of the steady state can be verified. With normal operating ramp settings and automatic switching sequences in place, the effect of a number of disturbances on the d.c. side of the system as well as in the a.c. systems may be checked, and the transient and fault recovery performances may be verified. Acceptance tests shall be defined between supplier and user in advance and may be performed at an appropriate time during the test schedule.
The acceptance tests necessary to verify whether acceptance criteria have been met, may have been performed wholly or in part during the commissioning period. To avoid unnecessary duplication of such tests, careful consideration should be given in advance as to when ac- ceptance tests are carried out. If acceptance tests are still outstanding or acceptance tests have to be repeated due to modifications, they should be performed during the transmission testing, or following trial operation, if appropriate. Correct operation of the HVDC system over an extended period of time is checked during the trial operation.
Complete and organized documentation of the system tests, which benefit both the supplier and the user, shall form part of the project documentation and contain all necessary data records, logs, etc, and if necessary a commentary and references. After all the above HVDC system tests have been completed, all functions have been verified and the HVDC system can be handed over to the users.