Pakistan & Saudi Grid Code: A Brief Comparison

INTRODUCTION

Grid code of a country is a living document which defines the roles, responsibilities, obligations and accountabilities on National Grid Company and other user of the system like generators, distribution entities and directly connected consumers. It defines the minimum technical requirements and exchanging information between the different participants. All the grid codes attempt to cover all the matters related to defining technical, design and operational criteria and standards, scheduling and dispatch of supply and demand resources, exchange of data and information and metering policies and system to account for the power and energy transactions in the grid.

National Grid Company of Pakistan (presently NTDC and NGC in new draft Grid Code 2022) has adopted all the best practices which are part of any modern/developed country. 2005 grid code was developed without the Renewable energy design, connection and operational guidelines and in the draft grid code all the addendums have been incorparated to give it a comprehensive document.  Below is given a brief review of the Saudi Arabian Grid Code (2016) and proposed Pakistani Grid Code (2022).

CHAPTER-1

·      Pak-Grid Code (PGC) have now more generic terms for all the participants in the light of new electricty market operationlization. NTDC is now divided into National Grid Company (NGC)/Transmission Network Operator (TNO) and System Operator (SO) previously called NPCC.

·      Grid Code (GC) enforcement and amendements will be responsibility of the SO not NGC however, being stake holder their input will be essential in any amendments.

·      Saudi Grid Code  (SGC) giving the responsibilty of GC enforcement and amenedments to Transmission Service Provider (TSP) and separating the grid infrastructure handling entity as National Grid (NG).

·      First chapter of both GCs defining the roles and responsibilities and disclaimer and instructions about force mejure and unforseen circumstances.

·      Dispute settlement process and committee memebers selection procedure are given in the very first chapter of SGC.

·      All other commitees (GC amendment, Derogation, GC supervisory etc) archtecture and mechanism is also present in first chapter of SGC.

·      Data exchange, data privacy codes and other data handling guidelines are also there in SGC.

·       PGC has first chapter under heading of Code Management (CM) which has a summary of all the chapters in it and also contains the information of commitees and other unforseen/force mejure events.

·      PGC has a reltionship diagram of different entities of the power sector and gives a broader picture of it.

REMARKS: First chapter of both SGC and PGC are now at par and updated version of PGC has covered all the aspect as in SGC.

CONNECTION CODE

·      Both SGC and PGC connection codes are emphsizing on providing a non-discrementory access to the transmission network.

·      Both are devising guidelines and specifying minimum connection and operational standards.

·      Both GCs are providing connection process and also defining the basic priciples of connection.

·      Both GCs are discussing the maximum MW injected into the system by generators and drawn by the consumers at the connection points.

·      Both GCs have discussions about proposed locations and tentaive connection dates for all the new users of the sytem.

·      Frequency variations and assciated maximum time to come to normal states have been discussed in connection code.

·      SGC allows 30 minutes to restore the system to whereas PGC has allowed the same for 20 Minutes.

·      Frequency variations magnitude (%age wise) in both GCs are of similar values. However SGC ihas base frequency of 60 Hz where as PGC has 50 Hz.

·      In both GCs permissible voltage variation ranges are also defined for different voltage level  in normal as well as contingency conditions.

·      PGC is considering 66 kV voltage as transmission voltage whereas SGC taking 110 kV as transmission voltage.

·      Pakistan grid code has vast voltage range in transmission (66 kV to 765 kV) whereas SGC has narrow range (110 kV- 380 kV).

·      Normal (±5%) and contingency (±10%) operating voltage limits are same in both GCs however 765 kV level (+4.58/-4.84% for both normal as well as contingency conditions)  has some varitions (% age wise).

·      PGC has defined the power system equipment, metring systems and other prtective equipment specification.

·      Both GCs have defined Harmonic distortion acceptable limits and have the same values for >=132kV in PGC and >=110 kV voltage levels i.e. 1.5% THD and 1% individual harminic.

·      For less than 132 kV system PGC has some greater values but SGC is strict to the same values even at 110 kV.

·      PGC has other important paramerts like minimum fault clearing time as per voltage levels and Low/High voltage ride through (LV/HV RT) technical specifications whereas SGC has the same concepts with different nomenclature (Voltage Withstand Capability Diagram). SGC has some customized parameter values whereas PGC has standard curves for both LV/HV RTS.

·      Both GCs have touched in details the topic related to reactive power support, permissible variations, operating margins of normal and contingency reserves and black start capabilities.

PLANNING CODE

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·      SGC has a broad term TSP and specifies its roles and responsibilities whereas PGC has two terms TNO and SO and defines their roles and responsibilities in Planning processes.

·      PGC assigns SO the responsibilities of spatial demand forecasting, generation planning (IGCEP) and Transmission System Expansion Plan (TSEP) for ten years on yearly rolling basis. It assigns roles of Transmission Investment Plan (TIP) for five years on yearly rolling basis.

·      SGC assigns all responsibilities to TSP and have no concepts like IGCEP. SGC has used more generic terms and covers wide areas. PGC has used more specific terms in planning code.

·      SGC has included load flow, contingency, short circuit, transient stability and grid reliability studies in planning process. Whereas PGC has another chapter named Transmission Planning criteria and standards (TPCS) for defining the required studies during planning process.

·      Data required with the connection application is well defined in the PGC as compared to SGC which has more general terms in it.

·      Responsibilities of SO and TNO and their submission dates are mentioned in PGC whereas SGC don’t have such pre-defined limitation in the document.

·      Both GCs have standard data sheets for facilitation of new users of the system seeking connection.

OPERATION CODE

Operation code specifies the technical, operational criterion followed by code participants and to be monitored by the system operator in PGC and TSP in SGC. The functions, disciplines and responsibilities of the SO/TSP are well defined in the license granted to them.  

·      Operational level demand forecast for different time horizons is responsibility of the SO in PGC and TSP in SGC. PGC has more clear instruction about preparation of these demand forecasts with pre-decided time schedule for each of these whereas SGC has some more broader terms for timelines of each of these activities.

·      Outage planning, operational reserves, frequency control mechanism and black start procedures are discussed in generic terms with broader view in both GCs.

·      Operational safety, communication protocols, testing, performance monitoring and event analysis pros and cons are discussed.

·      Both GCs have operational phase but PGC has much lower range (upto 3 months) whereas SGC has similar numbers in operational planning phase.

·      Both GCs have same concepts with different nomenclature and time horizons. PGC time horizons are narrower as compared to SGC.

·      PGC has defined terms like pre-operational phase (1-2 years), operational phase (from scheduled day upto 03 months), control phase (Real time operation and day ahead) and post control phase (day following the scheduled day) whereas SGC has defined terms like planning phase (03 months), programming phase ( 8 weeks ahead of scheduled day), control phase (Scheduled and day ahead of scheduled day) and post control phase (subsequent day).

·      Outage planning is discussed in both GCs with greater details. PGC demands notification/information from 10 MW and above even from DNO consumers whereas SGC deals with transmission connected consumers.

·      Forced outage information mechanism is strict in SGC which obligates the forced outage information dissemination by the participants within ten minutes of occurance whereas PGC is somewhat more flexible in this and allows 24 hours for reporting the forced outage.

In general, proposed Grid Cod of Pakistan (2022) and Saudi Grid Code (2016) has many similarities with only minor modifications. Above given comparison is a sample for this purpose and the other portions like metering, protection, IT and other allied portions of the both grid code are also similar ones with minor changes as per ground realities. Concepts are same but implementation time lines are varying as per their ground realities and network size. Saudi Arabian Economy and electricity production is much higher than Pakistan and so conditions vary accordingly. However, The proposed grid code has almost all the parameters as per grid code of developed country (Saudi Arabia is among G-20). It will be having more generic terms throughout the code rather than specific terms as were in Grid Code of 2005.