Page 24 of 190 Report No.: 6068396.50 TRF No. G99/1-4_V1.0 G99/1 Clause Requirement - Test Result - Remark Verdict (a) load flows, voltage regulation, frequency regulation, voltage unbalance, voltage flicker and harmonic voltage distortion; (b) earthing arrangements; (c) short circuit currents and the adequacy of protection arrangements; (d) System Stability; (e) resynchronisation to the Total System; (f) safety of personnel. P 9.6.3 Suitable equipment will need to be installed to detect that an island situation has occurred and an intertripping scheme is preferred to provide absolute discrimination at the time of the event.
Confirmation that a section of Distribution Network is operating in island mode, and has been disconnected from the Total System, will need to be transmitted to the Power Generating Module(s) protection and control schemes. P 9.6.4 The ESQCR requires that supplies to Customers are maintained within statutory limits at all times ie when they are supplied normally and when operating in island mode.
Detailed system studies including the capability of the Power Generating Module and its control / protections systems will be required to determine the capability of the Power Generating Module to meet these requirements immediately as the island is created and for the duration of the island mode operation. P 9.6.5 The ESQCR also require that Distribution Networks are earthed at all times. Generators, who are not permitted to operate their installations and plant with an earthed star- point when in parallel with the Distribution Network, must provide an earthing transformer or switched star-point earth for the purpose of maintaining an earth on the system when islanding occurs.
The design of the earthing system that will exist during island mode operation should be carefully considered to ensure statutory obligations are met and that safety of the Distribution Network to all users is maintained. Further details are provided in Section 8. P 9.6.6 Detailed consideration must be given to ensure that protection arrangements are adequate to satisfactorily clear the full range of potential faults within the islanded system taking into account the reduced fault currents and potential longer clearance times that are likely to be associated with an islanded system. P